Chapter 2

Question 1

which is anything that occupies space and has mass.

Answer 1

Matter

Question 2

is the amount of matter in an object

Answer 2

Mass

Question 3

is the gravitational force acting on an object of a given mass. For example, the weight of an apple results from the force of gravity “pulling” on the apple’s mass.

Answer 3

weight

Question 4

of an element is equal to the number of protons in each atom and, because the number of electrons is equal to the number of protons, the atomic number is also the number of electrons.

Answer 4

atomic number

Question 5

has no electrical charge

Answer 5

neutron

Question 6

has one positive charge

Answer 6

proton

Question 7

has one negative charge

Answer 7

electron

Question 8

of an element is the number of protons plus the number of neutrons in each atom. For example, the mass number for carbon is 12 because it has 6 protons and 6 neutrons.

Answer 8

mass number

Question 9

are two or more forms of the same element that have the same number of protons and electrons but a different number of neutrons. Thus, isotopes have the same atomic number but different mass numbers.

Answer 9

Isotopes

Question 10

of an element is the average mass of its naturally occurring isotopes, taking into account the relative abundance of each isotope. For example, the atomic mass of the element carbon is 12.01 Da

Answer 10

atomic mass

Question 11

1 mole (abbreviated mol). Stated another way, a mole of a substance contains Avogadro’s number of entities, such as atoms, ions, or molecules.

Answer 11

Avogadro’s number

Question 12

The mass of 1 mole of a substance expressed in grams, is a convenient way to determine the number of atoms in a sample of an element.

Answer 12

molar mass

Question 13

When this occurs, the numbers of protons and electrons are no longer equal, and a charged particle

Answer 13

ion

Question 14

Positively charged ions

Answer 14

cations

Question 15

negatively charged ions

Answer 15

anions

Question 16

forms when electrons are transferred between atoms, creating oppositely charged ions. For example, Na+ and Cl− are held together by ionic bonding to form an array of ions called sodium chloride (NaCl), or table salt (figure 2.5b,c).

Answer 16

ionic bond

Question 17

forms when atoms share one or more pairs of electrons. The sharing of electrons, rather than transfer of electrons, occurs because the atoms have similar electronegativities.

Answer 17

covalent bond

Question 18

The sharing of one pair of electrons by two atoms, A single line between the symbols of the atoms involved (e.g., H—H) represents a single covalent bond

Answer 18

single covalent bond

Question 19

results when two atoms share 4 electrons, 2 from each atom. When a carbon atom combines with two oxygen atoms to form carbon dioxide (CO2), two double covalent bonds form. Double covalent bonds are indicated by a double line between the atoms (O=C=O).

Answer 19

double covalent bond

Question 20

When electrons are shared equally between atoms, as in a hydrogen molecule

Answer 20

nonpolar covalent bonds

Question 21

However, atoms bound to one another by a covalent bond do not always share their electrons equally because in these situations the electronegativity of one atom is stronger than the electronegativity of the other atom.

Answer 21

polar covalent bonds

Question 22

is composed of two or more atoms chemically combined to form a structure that behaves as an independent unit. Sometimes the atoms that combine are of the same type, such as two hydrogen atoms combining to form a hydrogen molecule.

Answer 22

molecule

Question 23

is a substance resulting from the chemical combination of two or more different types of atoms. Water is a molecule that is also a compound because it is a combination of two different atoms, hydrogen and oxygen.

Answer 23

compound

Question 24

of a molecule or compound can be determined by adding up the atomic masses of its atoms (or ions). The term molecular mass is used for convenience for ionic compounds, even though they are not molecules.

Answer 24

molecular mass

Question 25

If the positively charged hydrogen of one molecule is attracted to the negatively charged oxygen, nitrogen, or fluorine of another molecule

Answer 25

hydrogen bond

Question 26

is the ability of one substance to dissolve in another—for example, sugar dissolving in water. Charged substances, such as sodium chloride, and polar substances, such as glucose, readily dissolve in water, whereas nonpolar substances, such as oils, do not.

Answer 26

Solubility

Question 27

or separate, from one another because cations are attracted to the negative ends of water molecules and anions are attracted to the positive ends of water molecules.

Answer 27

dissociate

Question 28

Cations and anions that dissociate in water, because they have the capacity to conduct an electric current, which is the flow of charged particles.

Answer 28

electrolytes

Question 29

Molecules that do not dissociate form solutions that do not conduct electricity, Pure water is a nonelectrolyte.

Answer 29

nonelectrolytes

Question 30

is when two or more reactants chemically combine to form a new and larger product.

Answer 30

synthesis reaction

Question 31

is the reverse of a synthesis reaction—a larger reactant is chemically broken down into two or more smaller products.

Answer 31

decomposition reaction

Question 32

the reaction can run in the opposite direction, so that the products are converted back to the original reactants.

Answer 32

reversible reaction

Question 33

When the rate of product formation is equal to the rate of the reverse reaction, At equilibrium, the amount of reactants relative to the amount of products remains constant.

Answer 33

equilibrium

Question 34

The loss of an electron by an atom

Answer 34

oxidation

Question 35

the gain of an electron

Answer 35

reduction

Question 36

Because one atom partially or completely loses an electron and another atom gains that electron, these reactions

Answer 36

oxidation-reduction reactions

Question 37

results from the position or movement of objects. Many of the activities of the human body, such as moving a limb, breathing, and circulating blood, involve mechanical energy.

Answer 37

Mechanical energy

Question 38

is a form of potential energy stored within the chemical bonds of a substance. In any chemical reaction, the potential energy in the chemical bonds of the reactants can be compared with the potential energy in the chemical bonds of the products.

Answer 38

Chemical energy

Question 39

are substances that increase the rate of chemical reactions without being permanently changed or depleted themselves.

Answer 39

Catalysts

Question 40

which are discussed in greater detail later in the chapter, are proteins that act as catalysts. Enzymes increase the rate of chemical reactions by lowering the activation energy necessary for the reaction to begin

Answer 40

Enzymes

Question 41

generally deals with substances that do not contain carbon, although a more rigorous definition is the lack of carbon-hydrogen bonds

Answer 41

Inorganic chemistry

Question 42

is the study of carbon-containing substances, with a few exceptions. For example, carbon monoxide (CO), carbon dioxide (CO2), and bicarbonate ions (HCO3−) are several important inorganic substances that contain carbon but lack C—H bonds.

Answer 42

Organic chemistry

Question 43

is the attraction of water to another water molecule. Examples of cohesion are the surface tension exhibited when water bulges over the top of a full glass without spilling over and when beads of water form on the skin

Answer 43

Cohesion

Question 44

is the same attractive force of hydrogen bonds of water that will also attract other molecules. An example of adhesion is the surface tension that draws water across a glass plate and holds a bead of water to the skin before it falls to the ground.

Answer 44

Adhesion

Question 45

is a combination of two or more substances physically blended together, but not chemically combined.

Answer 45

mixture

Question 46

is any mixture in which the substances are uniformly distributed. Solutions can be liquid, gas, or solid.

Answer 46

solution

Question 47

Solutions are often described in terms of one substance dissolving in another

Answer 47

solute

Answer 48

solvent

Question 49

is defined as a proton donor. A hydrogen ion (H+) is a proton because it results when an electron is lost from a hydrogen atom, which leaves just the proton nucleus.

Answer 49

acid

Question 50

is defined as a proton acceptor. Any substance that binds to (accepts) H+ is a base. Many bases function as proton acceptors by releasing hydroxide ions (OH−) when they dissociate.

Answer 50

base

Question 51

results if blood pH drops below 7.35, in which case the nervous system becomes depressed and the individual may become disoriented and possibly comatose

Answer 51

Acidosis

Question 52

results if blood pH rises above 7.45. Then the nervous system becomes overexcitable, and the individual may become extremely nervous or have convulsions

Answer 52

Alkalosis

Question 53

are the weak electrostatic attractions that exist between oppositely charged parts of molecules, or between ions and molecules. There is no exchange of electrons in intermolecular forces.

Answer 53

Intermolecular forces

Question 54

is an especially important molecule for storing and providing energy in all living organisms. It consists of adenosine (the sugar ribose with the nitrogenous base adenine) and three phosphate groups

Answer 54

Adenosine triphosphate (ă-den′ō-sēn trImages-fos′fāt; ATP