CHAPTER 2.1

Question 1

science of the structure and interactions of matter. All living and nonliving things consist of matter, which is anything that occupies space and has mass

Answer 1

chemistry

Question 2

the amount of matter in any object, which does not change.

Answer 2

mass

Question 3

the force of gravity acting on matter, does change

Answer 3

weight

Question 4

one or two letters of the element’s name in English, Latin, or another language.

Answer 4

chemical symbol

Question 5

oxygen, carbon, hydrogen, nitrogen

Answer 5

major elements

Question 6

calcium, phosphorus (P), potassium (K), sulfur (S), sodium, chlorine (Cl), magnesium (Mg), and iron (Fe)

Answer 6

lesser elements

Question 7

used to generate ATP, a molecule used by cells to temporarily store chemical energy.

Answer 7

oxygen

Question 8

backbone chains and rings of all organic molecules: carbohydrates, lipids (fats), proteins, and nucleic acids (DNA and RNA).

Answer 8

carbon

Question 9

ionized form (H+) makes body fluids more acidic.

Answer 9

hydrogen

Question 10

Component of all proteins and nucleic acids.

Answer 10

Nitrogen

Question 11

hardness of bones and teeth; ionized form (Ca2+) needed for blood clotting, release of some hormones, contraction of muscle, and many other processes.

Answer 11

Calcium

Question 12

Component of nucleic acids and ATP; required for normal bone and tooth structure

Answer 12

phosphorus

Question 13

Ionized form (K+) is the most plentiful cation (

Answer 13

potassium

Question 14

Component of some vitamins and many proteins

Answer 14

Sulfur

Question 15

most plentiful cation, essential for maintaining water balance

Answer 15

Sodium

Question 16

Ionized form (Cl−) is the most plentiful anion

Answer 16

chlorine

Question 17

needed for action of many enzymes

Answer 17

magnesium

Question 18

Ionized forms (Fe2+ and Fe3+) are part of hemoglobin and some enzyme

Answer 18

iron

Question 19

compose individual a toms

Answer 19

subatomic particles

Question 20

dense central core of an atom

Answer 20

nucleus

Question 21

regions around the nucleus

Answer 21

electron shells

Question 22

The first electron shell (nearest the nucleus) never holds more than _ electrons

Answer 22

2 Electrons

Question 23

e second shell holds a maximum of _ electrons, and the third can hold up to __ electrons.

Answer 23

8 and 18 electrons

Question 24

number of protons

Answer 24

atomic number

Question 25

the sum of its protons and neutrons

Answer 25

mass number

Question 26

atoms of an element that have different numbers of neutrons and therefore different mass numbers.

Answer 26

Isotopes

Question 27

unstable; their nuclei decay (spontaneously change

Answer 27

radioactive isotopes

Question 28

time required for half of the radioactive atoms

Answer 28

half-life

Question 29

standard unit for measuring the mass of atoms

Answer 29

dalton, also known as an atomic mass unit (amu)

Question 30

an atom that has a positive or negative charge

Answer 30

ion

Question 31

the process of giving up or gaining electrons

Answer 31

Ionization

Question 32

two or more atoms share electrons, the resulting combination

Answer 32

molecule

Question 33

an atom or group of atoms with an unpaired electron in the outermost shell.

Answer 33

free radical