instruction stringlengths 5 342 | input stringlengths 18 558 | output stringclasses 7
values | context stringlengths 31 6.57k |
|---|---|---|---|
Nonmetals are the second largest class of elements. | (A) true (B) false | A | Nonmetals are elements that generally do not conduct electricity. They are one of three classes of elements (the other two classes are metals and metalloids.) Nonmetals are the second largest of the three classes after metals. They are the elements located on the right side of the periodic table. Q: From left to right ... |
word that describes most metals | (A) metals (B) metalloids (C) nonmetals (D) mercury (E) ductile (F) bromine (G) brittle | E | Metals are elements that are good conductors of electricity. They are the largest of the three classes of elements. In fact, most elements are metals. Look back at the modern periodic table (Figure 6.3) in this chapters lesson "How Elements Are Organized." Find the metals in the table. They are all the elements that ar... |
only metal that is a liquid at room temperature | (A) metals (B) metalloids (C) nonmetals (D) mercury (E) ductile (F) bromine (G) brittle | D | Metals are elements that are good conductors of electricity. They are the largest of the three classes of elements. In fact, most elements are metals. Look back at the modern periodic table (Figure 6.3) in this chapters lesson "How Elements Are Organized." Find the metals in the table. They are all the elements that ar... |
Elements with eight valence electron are unreactive. | (A) true (B) false | A | Because the noble gases are the least reactive of all elements, their eight valence electrons are used as the standard for nonreactivity and to explain how other elements interact. This is stated as the octet (group of eight) rule. According to this rule, atoms react to form compounds that allow them to have a group of... |
class of elements that conduct electricity | (A) metals (B) metalloids (C) nonmetals (D) mercury (E) ductile (F) bromine (G) brittle | A | Metals are elements that can conduct electricity. They are one of three classes of elements (the other two classes are nonmetals and metalloids). Metals are by far the largest of the three classes. In fact, most elements are metals. All of the elements on the left side and in the middle of the periodic table, except fo... |
Fluorine is an example of a metalloid. | (A) true (B) false | B | Metalloids are elements that fall between metals and nonmetals in the periodic table. Just seven elements are metalloids, so they are the smallest class of elements. In Figure 6.3, they are color-coded orange. Examples of metalloids include boron (B), silicon (Si), and germanium (Ge). Metalloids have some properties of... |
Nonmetals tend to give up electrons. | (A) true (B) false | B | Nonmetals are elements that generally do not conduct electricity. They are one of three classes of elements (the other two classes are metals and metalloids.) Nonmetals are the second largest of the three classes after metals. They are the elements located on the right side of the periodic table. Q: From left to right ... |
Metals have relatively high melting points. | (A) true (B) false | A | Elements in the same class share certain basic similarities. In addition to conducting electricity, many metals have several other shared properties, including those listed below. Metals have relatively high melting points. This explains why all metals except for mercury are solids at room temperature. Most metals are ... |
Carbon is an example of a metalloid. | (A) true (B) false | B | Metalloids are elements that fall between metals and nonmetals in the periodic table. Just seven elements are metalloids, so they are the smallest class of elements. In Figure 6.3, they are color-coded orange. Examples of metalloids include boron (B), silicon (Si), and germanium (Ge). Metalloids have some properties of... |
Almost all nonmetals are solids are room temperature. | (A) true (B) false | B | As their name suggests, nonmetals generally have properties that are very different from the properties of metals. Properties of nonmetals include a relatively low boiling point, which explains why many of them are gases at room temperature. However, some nonmetals are solids at room temperature, including the three pi... |
Some nonmetals are semiconductors. | (A) true (B) false | B | Most metalloids have some physical properties of metals and some physical properties of nonmetals. For example, metals are good conductors of both heat and electricity, whereas nonmetals generally cannot conduct heat or electricity. And metalloids? They fall between metals and nonmetals in their ability to conduct heat... |
Silicon is the most common metalloid on Earth. | (A) true (B) false | A | Metalloids are elements that fall between metals and nonmetals in the periodic table. Just seven elements are metalloids, so they are the smallest class of elements. In Figure 6.3, they are color-coded orange. Examples of metalloids include boron (B), silicon (Si), and germanium (Ge). Metalloids have some properties of... |
Metals generally have fewer valence electrons than nonmetals. | (A) true (B) false | A | Metallic bonds are forces of attraction between positive metal ions and the valence electrons that are constantly moving around them (see the Figure 1.1). The valence electrons include their own and those of other, nearby ions of the same metal. The valence electrons of metals move freely in this way because metals hav... |
The number of valence electrons determines an elements reactivity. | (A) true (B) false | A | The electrons in the outer energy level of an atom are called valence electrons. It is valence electrons that are potentially involved in chemical reactions. The number of valence electrons determines an elements reactivity, or how likely the element is to react with other elements. The number of valence electrons also... |
Elements that want to gain electrons are usually metals. | (A) true (B) false | B | Metals are elements that can conduct electricity. They are one of three classes of elements (the other two classes are nonmetals and metalloids). Metals are by far the largest of the three classes. In fact, most elements are metals. All of the elements on the left side and in the middle of the periodic table, except fo... |
The ability of an element to conduct electricity depends on its number of neutrons. | (A) true (B) false | B | The number of protons per atom is always the same for a given element. However, the number of neutrons may vary, and the number of electrons can change. |
Neon is more reactive than fluorine. | (A) true (B) false | B | Reactivity is how likely an element is to react chemically with other elements. Some nonmetals are extremely reactive, whereas others are completely nonreactive. What explains this variation in nonmetals? The answer is their number of valence electrons. These are the electrons in the outer energy level of an atom that ... |
column of elements in the periodic table | (A) alkali metal (B) alkaline Earth metal (C) halogen (D) noble gas (E) transition metal (F) group (G) actinide | F | Columns of the modern table are called groups, as they are in Mendeleevs table. However, the modern table has many more groups18 compared with just 8 in Mendeleevs table. Elements in the same group have similar properties. For example, all elements in group 18 are colorless, odorless gases, such as neon (Ne). (Neon is ... |
Hydrogen is in the same group as the alkali metals because | (A) it is a metal (B) it is unreactive (C) it has one valence electron (D) it is in period 1 of the periodic table | C | Hydrogen is a very reactive gas, and the alkali metals are even more reactive. In fact, they are the most reactive metals and, along with the elements in group 17, are the most reactive of all elements. The reactivity of alkali metals increases from the top to the bottom of the group, so lithium (Li) is the least react... |
element in group 18 of the periodic table | (A) alkali metal (B) alkaline Earth metal (C) halogen (D) noble gas (E) transition metal (F) group (G) actinide | D | Group 13 of the periodic table is also called the boron group because boron (B) is the first element at the top of the group (see Figure 1.2). Boron is also the only metalloid in this group. The other four elements in the groupaluminum (Al), gallium (Ga), indium (In), and thallium (Tl)are all metals. Group 13 elements ... |
Alkaline Earth metals are less reactive than | (A) noble gases (B) transition metals (C) alkali metals (D) all of the above | C | All alkaline Earth metals have similar properties because they all have two valence electrons. They readily give up their two valence electrons to achieve a full outer energy level, which is the most stable arrangement of electrons. As a result, they are very reactive, although not quite as reactive as the alkali metal... |
metal in group 1 of the periodic table | (A) alkali metal (B) alkaline Earth metal (C) halogen (D) noble gas (E) transition metal (F) group (G) actinide | A | Groups 13-16 of the periodic table (orange in the Figure 1.1) are the only groups that contain elements classified as metalloids. Unlike other groups of the periodic table, which contain elements in just one class, groups 13-16 contain elements in at least two different classes. In addition to metalloids, they also con... |
Which groups of the periodic table contain one or more metalloids? | (A) groups 12 (B) groups 312 (C) groups 1316 (D) groups 1718 | C | Groups 13-16 of the periodic table (orange in the Figure 1.1) are the only groups that contain elements classified as metalloids. Unlike other groups of the periodic table, which contain elements in just one class, groups 13-16 contain elements in at least two different classes. In addition to metalloids, they also con... |
The most reactive nonmetals are elements in the | (A) boron group (B) nitrogen group (C) oxygen group (D) halogen group | D | The halogens are among the most reactive of all elements, although reactivity declines from the top to the bottom of the halogen group. Because all halogens have seven valence electrons, they are eager to gain one more electron. Doing so gives them a full outer energy level, which is the most stable arrangement of elec... |
radioactive transition metal | (A) alkali metal (B) alkaline Earth metal (C) halogen (D) noble gas (E) transition metal (F) group (G) actinide | G | Transition metals include the elements that are most often placed below the periodic table (the pink- and purple- shaded elements in the Figure 1.1). Those that follow lanthanum (La) are called lanthanides. They are all relatively reactive for transition metals. Those that follow actinium (Ac) are called actinides. The... |
metal in group 2 of the periodic table | (A) alkali metal (B) alkaline Earth metal (C) halogen (D) noble gas (E) transition metal (F) group (G) actinide | B | Groups 13-16 of the periodic table (orange in the Figure 1.1) are the only groups that contain elements classified as metalloids. Unlike other groups of the periodic table, which contain elements in just one class, groups 13-16 contain elements in at least two different classes. In addition to metalloids, they also con... |
All elements in the carbon group | (A) are solids are room temperature (B) have four valence electrons (C) are not very reactive (D) all of the above | D | Carbon is a nonmetal in group 14 of the periodic table. Like other group 14 compounds, carbon has four valence electrons. Valence electrons are the electrons in the outer energy level of an atom that are involved in chemical bonds. The valence electrons of carbon are shown in Figure 9.1. |
metal in group 3 of the periodic table | (A) alkali metal (B) alkaline Earth metal (C) halogen (D) noble gas (E) transition metal (F) group (G) actinide | E | Groups 13-16 of the periodic table (orange in the Figure 1.1) are the only groups that contain elements classified as metalloids. Unlike other groups of the periodic table, which contain elements in just one class, groups 13-16 contain elements in at least two different classes. In addition to metalloids, they also con... |
nonmetal in group 17 of the periodic table | (A) alkali metal (B) alkaline Earth metal (C) halogen (D) noble gas (E) transition metal (F) group (G) actinide | C | Group 15 of the periodic table is also called the nitrogen group. The first element in the group is the nonmetal nitrogen (N), followed by phosphorus (P), another nonmetal. Arsenic (As) (Figure 1.4) and antimony (Sb) are the metalloids in this group, and bismuth (Bi) is a metal. All group 15 elements have five valence ... |
Elements in group 1 include | (A) hydrogen (B) alkali metals (C) alkaline Earth metals (D) two of the above | D | Group 15 of the periodic table is also called the nitrogen group. The first element in the group is the nonmetal nitrogen (N), followed by phosphorus (P), another nonmetal. Arsenic (As) (Figure 1.4) and antimony (Sb) are the metalloids in this group, and bismuth (Bi) is a metal. All group 15 elements have five valence ... |
Alkali metals are | (A) soft (B) high in density (C) not very reactive (D) all of the above | A | Besides being very reactive, alkali metals share a number of other properties. Alkali metals are all solids at room temperature. Alkali metals are low in density, and some of them float on water. Alkali metals are relatively soft. Some are even soft enough to cut with a knife, like the sodium pictured in the Figure 1.1... |
Which statement about alkaline Earth metals is true? | (A) They are more reactive than alkali metals (B) They are always found combined with other elements (C) Some of them are liquids at room temperature (D) They are all gold in color | B | The alkaline Earth metals include all the elements in group 2 (see Figure 6.10). These metals have just two valence electrons, so they are very reactive, although not quite as reactive as the alkali metals. In nature, they are always found combined with other elements. Alkaline Earth metals are silvery grey in color. T... |
The most reactive metals are the transition metals. | (A) true (B) false | B | Groups 3-12 of the periodic table contain transition metals (see Figure 6.11). Transition metals have more valence electrons and are less reactive than metals in the first two metal groups. The transition metals are shiny. Many are silver colored. They tend to be very hard, with high melting and boiling points. All exc... |
Transition metals tend to | (A) be shiny (B) boil at low temperatures (C) be very soft (D) be extremely reactive | A | Groups 3-12 of the periodic table contain transition metals (see Figure 6.11). Transition metals have more valence electrons and are less reactive than metals in the first two metal groups. The transition metals are shiny. Many are silver colored. They tend to be very hard, with high melting and boiling points. All exc... |
Alkaline Earth metals have three valence electrons. | (A) true (B) false | B | All alkaline Earth metals have similar properties because they all have two valence electrons. They readily give up their two valence electrons to achieve a full outer energy level, which is the most stable arrangement of electrons. As a result, they are very reactive, although not quite as reactive as the alkali metal... |
The only nonmetal in the carbon group is | (A) nitrogen (B) boron (C) carbon (D) oxygen | C | Carbon is a nonmetal in group 14 of the periodic table. Like other group 14 compounds, carbon has four valence electrons. Valence electrons are the electrons in the outer energy level of an atom that are involved in chemical bonds. The valence electrons of carbon are shown in Figure 9.1. |
Halogens form salts when they combine with | (A) alkali metals (B) alkaline Earth metals (C) transition metals (D) all metals | A | Halide minerals are salts that form when salt water evaporates. Halite is a halide mineral, but table salt (see Figure bond with various metallic atoms to make halide minerals. All halides are ionic minerals, which means that they are typically soluble in water. Two carbonate minerals: (a) deep blue azurite and (b) opa... |
Mercury is the only metal that is a liquid at room temperature. | (A) true (B) false | A | Figure 1.3 shows a diagram of Mercurys interior. Mercury is one of the densest planets. Its relatively large, liquid core, made mostly of melted iron, takes up about 42% of the planets volume. |
Nobles gases are | (A) colorless (B) odorless (C) reactive (D) two of the above | D | Group 18 elements are nonmetals called noble gases (see Figure 6.14). They are all colorless, odorless gases. Their outer energy level is also full, so they are the least reactive elements. In nature, they seldom combine with other substances. For a short video about the noble gases and their properties, go to this URL... |
Boron is an example of an element in the metalloids class. | (A) true (B) false | A | Metalloids are elements that fall between metals and nonmetals in the periodic table. Just seven elements are metalloids, so they are the smallest class of elements. In Figure 6.3, they are color-coded orange. Examples of metalloids include boron (B), silicon (Si), and germanium (Ge). Metalloids have some properties of... |
Helium is an element in the group called the halogens. | (A) true (B) false | B | Elements in group 17 are called halogens (see Figure 6.13). They are highly reactive nonmetals with seven valence electrons. The halogens react violently with alkali metals, which have one valence electron. The two elements combine to form a salt. For example, the halogen chlorine (Cl) and the alkali metal sodium (Na) ... |
Hydrogen is an alkali metal. | (A) true (B) false | B | Hydrogen is a very reactive gas, and the alkali metals are even more reactive. In fact, they are the most reactive metals and, along with the elements in group 17, are the most reactive of all elements. The reactivity of alkali metals increases from the top to the bottom of the group, so lithium (Li) is the least react... |
Alkali metals are found only in compounds. | (A) true (B) false | A | All the elements in group 1 have just one valence electron, so they are highly reactive. Group 1 is shown in Figure element in the universe. All the other elements in group 1 are alkali metals. They are the most reactive of all metals, and along with the elements in group 17, the most reactive elements. Because alkali ... |
Some alkali metals can float on water. | (A) true (B) false | A | Besides being very reactive, alkali metals share a number of other properties. Alkali metals are all solids at room temperature. Alkali metals are low in density, and some of them float on water. Alkali metals are relatively soft. Some are even soft enough to cut with a knife, like the sodium pictured in the Figure 1.1... |
Calcium is an alkali metal. | (A) true (B) false | B | For a better understanding of alkaline Earth metals, lets take a closer look at two of them: calcium (Ca) and strontium (Sr). Calcium is a soft, gray, nontoxic alkaline Earth metal. Although pure calcium doesnt exist in nature, calcium compounds are very common in Earths crust and in sea water. Calcium is also the most... |
There is just one group of transition metals. | (A) true (B) false | B | Transition metals are all the elements in groups 3-12 of the periodic table. In the periodic table pictured in Figure known elements. In addition to copper (Cu), well known examples of transition metals include iron (Fe), zinc (Zn), silver (Ag), and gold (Au) (Copper (Cu) is pictured in its various applications in the ... |
Many of the actinides do not occur in nature. | (A) true (B) false | A | In elements with more than 83 protons, all of the isotopes are radioactive. In the Figure 1.1, these are the elements with a yellow background. The force of repulsion among all those protons makes the nuclei unstable. Elements with more than 92 protons have such unstable nuclei that they dont even exist in nature. They... |
Elements in the oxygen group have eight valence electrons. | (A) true (B) false | B | The number of valence electrons in an atom is reflected by its position in the periodic table of the elements (see the periodic table in the Figure 1.1). Across each row, or period, of the periodic table, the number of valence electrons in groups 1-2 and 13-18 increases by one from one element to the next. Within each ... |
Selenium is an alkaline Earth metal. | (A) true (B) false | B | The alkaline Earth metals include all the elements in group 2 (see Figure 6.10). These metals have just two valence electrons, so they are very reactive, although not quite as reactive as the alkali metals. In nature, they are always found combined with other elements. Alkaline Earth metals are silvery grey in color. T... |
The halogen group includes only gases. | (A) true (B) false | B | The halogen group is quite diverse. It includes elements that occur in three different states of matter at room temperature. Fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. Halogens also vary in color, as you can see in the Figure 1.2. Fluorine and chlorine are green, bromine i... |
Noble gases are found only in combination with other elements. | (A) true (B) false | B | Noble gases are the least reactive of all known elements. Thats because with eight valence electrons, their outer energy levels are full. The only exception is helium, which has just two electrons. But helium also has a full outer energy level, because its only energy level (energy level 1) can hold a maximum of two el... |
Subscripts in a chemical formula are used to show the number of | (A) molecules in a substance (B) atoms of each element in a compound (C) different elements in a compound (D) protons in an element | B | In a chemical formula, the elements in a compound are represented by their chemical symbols, and the ratio of different elements is represented by subscripts. Consider the compound water as an example. Each water molecule contains two hydrogen atoms and one oxygen atom. Therefore, the chemical formula for water is: H2 ... |
There are millions of unique substances in the universe because elements can combine in many different ways to form | (A) mixtures (B) solutions (C) compounds (D) ions | C | There are millions of different substances in the world. Thats because elements can combine in many different ways to form new substances. In fact, most elements are found in compounds. A compound is a unique substance that forms when two or more elements combine chemically. An example is water, which forms when hydrog... |
Which chemical formula represents the compound hydrogen peroxide? | (A) H2 O (B) HO2 (C) H2 O 2 (D) H2 O 3 | C | The same elements may combine in different ratios. If they do, they form different compounds. Figure 7.2 shows some examples. Both water (H2 O) and hydrogen peroxide (H2 O2 ) consist of hydrogen and oxygen. However, they have different ratios of the two elements. As a result, water and hydrogen peroxide are different c... |
Water is an example of a(n) | (A) unique substance (B) chemical compound (C) covalent compound (D) all of the above | D | Water vapor is an example of a gas. A gas is matter that has neither a fixed volume nor a fixed shape. Instead, a gas takes both the volume and the shape of its container. It spreads out to take up all available space. You can see an example in Figure 4.6. |
The chemical formula HCl represents the compound named | (A) hydrogen chloride (B) hydrogen carbide (C) methane (D) none of the above | A | An acid is an ionic compound that produces positive hydrogen ions (H+ ) when dissolved in water. An example is hydrogen chloride (HCl). When it dissolves in water, its hydrogen ions and negative chloride ions (Cl ) separate, forming hydrochloric acid. This can be represented by the equation: HCl H2 O + ! H + Cl |
Which statement is true about water and hydrogen peroxide? | (A) Both substances have the same properties (B) Both substances have the same chemical formula (C) Both substances consist of hydrogen and oxygen (D) Both substances are mixtures of elements | C | The same elements may combine in different ratios. If they do, they form different compounds. Figure 7.2 shows some examples. Both water (H2 O) and hydrogen peroxide (H2 O2 ) consist of hydrogen and oxygen. However, they have different ratios of the two elements. As a result, water and hydrogen peroxide are different c... |
Chemical bonds always involve | (A) ions (B) atoms (C) metals (D) electrons | D | A chemical bond is a force of attraction between atoms or ions. Bonds form when atoms share or transfer valence electrons. Valence electrons are the electrons in the outer energy level of an atom that may be involved in chemical interactions. Valence electrons are the basis of all chemical bonds. Q: Why do you think th... |
Which statement is true about carbon dioxide and carbon monoxide? | (A) Both compounds consist of carbon and oxygen (B) Both compounds have all the same properties (C) Both compounds are harmless gases (D) all of the above | A | Carbon monoxide (CO) is toxic to both plants and animals. CO is deadly to people in a confined space, such as a closed home. Carbon monoxide is odorless and colorless, so people cant tell when they are breathing it. Thats why homes should have carbon monoxide detectors. You can see one in Figure 22.7. |
How many valence electrons does an oxygen atom have? | (A) 2 (B) 4 (C) 6 (D) 8 | C | The number of valence electrons in an atom is reflected by its position in the periodic table of the elements (see the periodic table in the Figure 1.1). Across each row, or period, of the periodic table, the number of valence electrons in groups 1-2 and 13-18 increases by one from one element to the next. Within each ... |
The ratio of elements in a given compound | (A) is always 2 to 1 (B) is always the same (C) may vary (D) two of the above | B | A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions that share or transfer valence electrons. Click image ... |
A given compound always has the same | (A) chemical formula (B) composition (C) volume (D) two of the above | D | A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions that share or transfer valence electrons. Click image ... |
When there is just one atom of an element in a molecule, what subscript is used for the element? | (A) 1 (B) 0 (C) 2 (D) No subscript is used | D | In a chemical formula, the elements in a compound are represented by their chemical symbols, and the ratio of different elements is represented by subscripts. Consider the compound water as an example. Each water molecule contains two hydrogen atoms and one oxygen atom. Therefore, the chemical formula for water is: H2 ... |
An oxygen atom has eight valence electrons. | (A) true (B) false | B | Covalent bonds form because they give atoms a more stable arrangement of electrons. Look at the oxygen atoms in the Figure 1.2. Alone, each oxygen atom has six valence electrons. By sharing two pairs of valence electrons, each oxygen atom has a total of eight valence electrons. This fills its outer energy level, giving... |
A molecule of carbon monoxide has two carbon atoms and one oxygen atom. | (A) true (B) false | B | A molecule is any combination of two or more atoms. The oxygen in the air we breathe is two oxygen atoms connected by a chemical bond to form O2 , or molecular oxygen. A carbon dioxide molecule is a combination of one carbon atom and two oxygen atoms, CO2 . Because carbon dioxide includes two different elements, it is ... |
The types of bonds in chemical compounds determine many of their properties. | (A) true (B) false | A | There are different types of compounds. They differ in the nature of the bonds that hold their atoms together. The type of bonds in a compound determines many of its properties. Three types of bonds are ionic, covalent, and metallic bonds. You will read about these three types in later lessons. You can also learn more ... |
The same elements may form different compounds. | (A) true (B) false | A | There are millions of different substances in the world. Thats because elements can combine in many different ways to form new substances. In fact, most elements are found in compounds. A compound is a unique substance that forms when two or more elements combine chemically. An example is water, which forms when hydrog... |
The chemical formula for carbon dioxide is CO2 . | (A) true (B) false | A | The short term cycling of carbon begins with carbon dioxide (CO2 ) in the atmosphere. |
A hydrogen atom has two electrons. | (A) true (B) false | B | To understand why chemical bonds form, consider the common compound known as water, or H2 O. It consists of two hydrogen (H) atoms and one oxygen (O) atom. As you can see in the on the left side of the Figure 1.1, each hydrogen atom has just one electron, which is also its sole valence electron. The oxygen atom has six... |
Each element is represented by a unique chemical formula. | (A) true (B) false | B | In a chemical formula, the elements in a compound are represented by their chemical symbols, and the ratio of different elements is represented by subscripts. Consider the compound water as an example. Each water molecule contains two hydrogen atoms and one oxygen atom. Therefore, the chemical formula for water is: H2 ... |
The compound carbon dioxide has twice as many oxygen atoms as carbon atoms. | (A) true (B) false | A | Look at the Figure 1.2 of water (H2 O) and hydrogen peroxide (H2 O2 ), and read about these two compounds. Both compounds consist of hydrogen and oxygen, but they have different ratios of the two elements. As a result, water and hydrogen peroxide are different compounds with different properties. If youve ever used hyd... |
The same elements may combine in different ratios to form the same compound. | (A) true (B) false | B | There are millions of different substances in the world. Thats because elements can combine in many different ways to form new substances. In fact, most elements are found in compounds. A compound is a unique substance that forms when two or more elements combine chemically. An example is water, which forms when hydrog... |
Any molecule that contains only hydrogen and oxygen is water. | (A) true (B) false | B | Water is a simple chemical compound. Each molecule of water contains two hydrogen atoms (H2 ) and one oxygen atom (O). Thats why the chemical formula for water is H2 O. If water is so simple, why is it special? Water is one of the few substances that exists on Earth in all three states of matter. Water occurs as a gas,... |
Different types of compounds differ in the types of bonds that hold their atoms together. | (A) true (B) false | A | There are different types of compounds. They differ in the nature of the bonds that hold their atoms together. The type of bonds in a compound determines many of its properties. Three types of bonds are ionic, covalent, and metallic bonds. You will read about these three types in later lessons. You can also learn more ... |
Both coal and diamond consist of atoms of carbon that are bonded together. | (A) true (B) false | A | Diamond is a form of carbon in which each carbon atom is covalently bonded to four other carbon atoms. This forms a strong, rigid, three-dimensional structure (see Figure 1.1). Diamond is the hardest natural substance, and no other natural substance can scratch it. This property makes diamonds useful for cutting and gr... |
Most of the unique substances on Earth are compounds. | (A) true (B) false | A | There are millions of different substances in the world. Thats because elements can combine in many different ways to form new substances. In fact, most elements are found in compounds. A compound is a unique substance that forms when two or more elements combine chemically. An example is water, which forms when hydrog... |
When atoms combine chemically they form mixtures. | (A) true (B) false | B | Not all combined substances are compounds. Some are mixtures. A mixture is a combination of two or more substances in any proportion. The substances in a mixture may be elements or compounds. The substances dont combine chemically to form a new substance, as they do in a compound. Instead, they keep their original prop... |
A chemical bond consists of matter that connects two different atoms. | (A) true (B) false | B | A chemical bond is a force of attraction between atoms or ions. Bonds form when atoms share or transfer valence electrons. Valence electrons are the electrons in the outer energy level of an atom that may be involved in chemical interactions. Valence electrons are the basis of all chemical bonds. Q: Why do you think th... |
pure substance that cannot be separated into any other substances | (A) chemical bond (B) chemical formula (C) compound (D) valence electron (E) element (F) molecule (G) ionic | E | A pure substance is called an element. An element is a pure substance because it cannot be separated into any other substances. Currently, 92 different elements are known to exist in nature, although additional elements have been formed in labs. All matter consists of one or more of these elements. Some elements are ve... |
unique substance that forms when elements combine chemically | (A) chemical bond (B) chemical formula (C) compound (D) valence electron (E) element (F) molecule (G) ionic | C | There are millions of different substances in the world. Thats because elements can combine in many different ways to form new substances. In fact, most elements are found in compounds. A compound is a unique substance that forms when two or more elements combine chemically. An example is water, which forms when hydrog... |
particle of a compound that forms when atoms bond together | (A) chemical bond (B) chemical formula (C) compound (D) valence electron (E) element (F) molecule (G) ionic | F | The smallest particle of a compound that still has the compounds properties is a molecule. A molecule consists of two or more atoms that are joined together. For example, a molecule of water consists of two hydrogen atoms joined to one oxygen atom (see Figure 3.10). You can learn more about molecules at this link: Som... |
one of three types of chemical compounds | (A) chemical bond (B) chemical formula (C) compound (D) valence electron (E) element (F) molecule (G) ionic | G | There are different types of compounds. They differ in the nature of the bonds that hold their atoms together. The type of bonds in a compound determines many of its properties. Three types of bonds are ionic, covalent, and metallic bonds. You will read about these three types in later lessons. You can also learn more ... |
symbol representing a chemical compound | (A) chemical bond (B) chemical formula (C) compound (D) valence electron (E) element (F) molecule (G) ionic | B | Elements are represented by chemical symbols. Examples are H for hydrogen and O for oxygen. Compounds are represented by chemical formulas. Youve already seen the chemical formula for water. Its H2 O. The subscript 2 after the H shows that there are two atoms of hydrogen in a molecule of water. The O for oxygen has no ... |
particle in the outer energy level of an atom | (A) chemical bond (B) chemical formula (C) compound (D) valence electron (E) element (F) molecule (G) ionic | D | An electron is a particle outside the nucleus of an atom that has a negative electric charge. The charge of an electron is opposite but equal to the charge of a proton. Atoms have the same number of electrons as protons. As a result, the negative and positive charges "cancel out." This makes atoms electrically neutral.... |
force of attraction between atoms or ions that share or transfer electrons | (A) chemical bond (B) chemical formula (C) compound (D) valence electron (E) element (F) molecule (G) ionic | A | A chemical bond is a force of attraction between atoms or ions. Bonds form when atoms share or transfer valence electrons. Valence electrons are the electrons in the outer energy level of an atom that may be involved in chemical interactions. Valence electrons are the basis of all chemical bonds. Q: Why do you think th... |
Ionic compounds form when ions share electrons. | (A) true (B) false | B | Ionic compounds contain ions of metals and nonmetals held together by ionic bonds. Ionic compounds do not form molecules. Instead, many positive and negative ions bond together to form a structure called a crystal. You can see an example of a crystal in Figure 7.5. It shows the ionic compound sodium chloride. Positive ... |
When halogens form ions they | (A) become positive in charge (B) become negative in charge (C) gain two electrons (D) two of the above | B | Ions are highly reactive, especially as gases. They usually react with ions of opposite charge to form neutral compounds. For example, positive sodium ions and negative chloride ions react to form the neutral compound sodium chloride, commonly known as table salt. This occurs because oppositely charged ions attract eac... |
In sodium chloride, sodium loses an electron to chlorine. | (A) true (B) false | A | An ionic bond is the force of attraction that holds together positive and negative ions. It forms when atoms of a metallic element give up electrons to atoms of a nonmetallic element. Figure 7.3 shows how this happens. In row 1 of Figure 7.3, an atom of sodium donates an electron to an atom of chlorine (Cl). By losing ... |
Which two elements would not form ionic bonds? | (A) calcium and lithium (B) calcium and oxygen (C) lithium and oxygen (D) calcium and carbon | A | Ionic bonds form only between metals and nonmetals. Thats because metals want to give up electrons, and nonmetals want to gain electrons. Find sodium (Na) in the Figure 1.2. Sodium is an alkali metal in group 1. Like all group 1 elements, it has just one valence electron. If sodium loses that one electron, it will have... |
Ionic bonds form only between atoms of nonmetals. | (A) true (B) false | B | Ionic bonds form only between metals and nonmetals. Thats because metals want to give up electrons, and nonmetals want to gain electrons. Find sodium (Na) in the Figure 1.2. Sodium is an alkali metal in group 1. Like all group 1 elements, it has just one valence electron. If sodium loses that one electron, it will have... |
Energy is released when | (A) valence electrons are removed from an atom (B) valence electrons are gained by an atom (C) a positive ion forms (D) two of the above | B | Nuclear energy is produced by splitting the nucleus of an atom. This releases a huge amount of energy. |
A sodium ion has a charge of | (A) -1 (B) -2 (C) +1 (D) +2 | C | An ionic bond is the force of attraction that holds together positive and negative ions. It forms when atoms of a metallic element give up electrons to atoms of a nonmetallic element. Figure 7.3 shows how this happens. In row 1 of Figure 7.3, an atom of sodium donates an electron to an atom of chlorine (Cl). By losing ... |
The amount of energy needed to form an ion depends only on the number of valence electrons. | (A) true (B) false | B | It takes energy to remove valence electrons from an atom because the force of attraction between the negative electrons and the positive nucleus must be overcome. The amount of energy needed depends on the element. Less energy is needed to remove just one or a few valence electrons than many. This explains why sodium a... |
Francium has the same number of valence electrons as lithium. | (A) true (B) false | A | Although all group 1 elements share certain properties, such as being very reactive, they are not alike in every way. Three different group 1 elements are described in more detail below. Notice the ways in which they differ from one another. Q: Why do you think hydrogen gas usually exists as diatomic molecules? A: Each... |
In a given metals group of the periodic table, compared with elements closer to the top of the table, elements closer to the bottom | (A) have valence electrons that are farther from the nucleus (B) have valence electrons that are harder to remove from the atom (C) need more energy to form positive ions (D) all of the above | A | Groups 3-12 of the periodic table contain transition metals (see Figure 6.11). Transition metals have more valence electrons and are less reactive than metals in the first two metal groups. The transition metals are shiny. Many are silver colored. They tend to be very hard, with high melting and boiling points. All exc... |
Alkali metals release the most energy when they become ions. | (A) true (B) false | B | It takes energy to remove valence electrons from an atom. The force of attraction between the negative electrons and positive nucleus must be overcome. The amount of energy needed depends on the element. Less energy is needed to remove just one or a few electrons than many. This explains why sodium and other alkali met... |
Salt consists of molecules of sodium and chloride ions. | (A) true (B) false | B | Compounds like sodium chloride form structures called crystals. A crystal is a rigid framework of many ions locked together in a repeating pattern. Ions are electrically charged forms of atoms. You can see a crystal of sodium chloride in the Figure 1.3. It is made up of many sodium and chloride ions. Sodium and chlorin... |
When an atom of iodine becomes an ion, it is named iodide. | (A) true (B) false | A | Like fluoride, other negative ions usually have names ending in -ide. Positive ions, on the other hand, are just given the element name followed by the word ion. For example, when a sodium atom loses an electron, it becomes a positive sodium ion. The charge of an ion is indicated by a plus (+) or minus sign (-), which ... |
Ionic compounds are usually liquids at room temperature. | (A) true (B) false | B | Ionic compounds have many uses. Some are shown in the Figure 1.2. Many ionic compounds are used in industry. The human body needs several ions for good health. Having low levels of the ions can endanger important functions such as heartbeat. Solutions of ionic compounds can be used to restore the ions. |
Water is an example of an ionic compound. | (A) true (B) false | B | Water (H2 O) is an example of a chemical compound. Water molecules always consist of two atoms of hydrogen and one atom of oxygen. Like water, all other chemical compounds consist of a fixed ratio of elements. It doesnt matter how much or how little of a compound there is. It always has the same composition. |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.