Chapter 2: Atoms and Molecules

Question 1

Element

Answer 1

a substance that cannot be broken down into a simpler substance by ordinary chemical reactions

Question 2

Atoms

Answer 2

the smallest portion of an element that retains its chemical properties

Question 3

Atomic nucleus

Answer 3

In the atom, has protons and neutrons in it

Question 4

Electrons

Answer 4

Light negatively charged particles that move around in energy levels surrounding the atomic nucleus

Question 5

Protons

Answer 5

heavy positively charged particles located in the atomic nucleus

Question 6

Neutrons

Answer 6

heavy uncharged particles located in the atomic nucleus

Question 7

Valence electrons

Answer 7

electrons farthest away from the nucleus that generally have greater energy

Question 8

Periodic table

Answer 8

A chart of all known elements arranged according to their atomic number

Question 9

atomic number

Answer 9

Indicates the number of protons

Question 10

chemical symbol

Answer 10

a abbreviation for the name of an element

Question 11

atomic mass

Answer 11

indicates the number of protons and neutrons

Question 12

compound

Answer 12

atoms of two or more elements combined in a fixed ratio

Question 13

molecule

Answer 13

contains two or more atoms that are joined together very strongly by covalent bonds

Question 14

Chemical formula

Answer 14

describes the types and numbers of atoms present in a compound

Question 15

structural formula

Answer 15

describes how atoms of a compound are arranged in space

Question 16

chemical equations

Answer 16

describe the reaction that occurs between elements and compounds to produce a given compound

Question 17

bond

Answer 17

force that holds atoms together in a compound

Question 18

bond energy

Answer 18

the energy that is necessary to break a bond between atoms

Question 19

covalent bond

Answer 19

atoms share electrons, they can be polar or nonpolar

Question 20

ionic bond

Answer 20

one atom gives up electrons to another atom

Question 21

ion

Answer 21

charged atom

Question 22

cation

Answer 22

formed when atoms with 1, 2, or 3 valence electrons lose electrons to other atoms and become positively charged

Question 23

anion

Answer 23

formed when atoms with 5, 6, or 7 valence electrons gain electrons from other atoms and become negatively charged

Question 24

Solvent

Answer 24

chemical that causes a compound to dissociate

Question 25

solute

Answer 25

compound that is dissolved in a solvent

Question 26

hydrogen bond

Answer 26

weak interaction between a slightly negatively charged atom in a polar molecule and a hydrogen that is bound to nitrogen or oxygen

Question 27

Van de Waals interactions

Answer 27

result from movement of electrons in atoms within close proximity

Question 28

cohesive

Answer 28

water molecules tend to stick to one another

Question 29

adhesive

Answer 29

water has the ability to stick to other substances

Question 30

capillary action

Answer 30

water has a tendency to move in narrow tubes, even against the force of gravity

Question 31

surface tension

Answer 31

molecules at waters surface crowd together, producing a strong layer as they are pulled downward by the attraction of water molecules beneath them

Question 32

dissolves compounds

Answer 32

polar water molecules can dissolve many types of compounds and exclude others

Question 33

hydrophilic

Answer 33

water loving substances

Question 34

hydrophobic

Answer 34

water fearing substances

Question 35

acid

Answer 35

any substance that dissolves in solution to yield a hydrogen ion and anion

Question 36

base

Answer 36

any substance that dissolves in solution to yield a hydroxide ion and a cation

Question 37

pH

Answer 37

convenient measure of the H+ concentration of a solution

Question 38

buffer

Answer 38

substances that resists changes in pH when an acid or base is added

Question 39

acids and bases form to make what

Answer 39

salt water