Chapter 2

Question 1

Law of definite proportions

Answer 1

All samples of a compound have the same ratio of their elements– if the ratio changes, the compound changes!

Question 2

Law of multiple proportions

Answer 2

If elements form multiple compounds, ratio of second element to first in the two is proportional

Question 3

Mass number

Answer 3

number of protons + number of neutrons

Question 4

Atomic number

Answer 4

number of protons in nucleus

Question 5

Isotopes

Answer 5

have the same atomic # but different mass numbers

Question 6

Types of Radioactive Decay

Answer 6

1. Alpha decay: emission of an alpha particle
2. Beta decay: emission of an alpha particle
3. Gamma decay: emission of pure energy

Question 7

Half-life

Answer 7

amount of time required for amount of substance to be reduced to half the initial amount reflects the rate of reaction/decay

Question 8

Cations

Answer 8

positive charge

Question 9

Anions

Answer 9

negative charge

Question 10

Atomic mass

Answer 10

is the mass of an atom in atomic mass units (amu)

Question 11

average atomic mass

Answer 11

the weighted average of all of the naturally occurring isotopes of the element

Question 12

mole (mol)

Answer 12

the amount of a substance that contains as many elementary entities as there are atoms

Question 13

Avogadro’s number (NA)

Answer 13

6.022 x 10^23

Question 14

Molar mass

Answer 14

the mass of 1 mole of X in grams

Question 15

Molecule

Answer 15

two or more atoms in a fixed ratio;shared electrons in chemical bond

Question 16

Compounds

Answer 16

contain at least two different atoms

Question 17

Ionic Compounds

Answer 17

1. Composed of cations and anions
2. Generally formed between metals and nonmetals