Ch 3 Vocab

Question 1

Law of conservation of mass

Answer 1

States that mass is neither created nor destroyed during ordinary chemical reactions or physical changes

Question 2

Law of definite proportions

Answer 2

The fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound

Question 3

Law of multiple proportions

Answer 3

If two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers

Question 4

Atom

Answer 4

The smallest particle of an element that retains the chemical properties of that element

Question 5

Nuclear forces

Answer 5

Short-range proton-neutron, proton-proton, and neutron-neutron forces that hold the nuclear particles together

Question 6

Atomic number

Answer 6

The number of protons of each atom of that element

Question 7

Isotope

Answer 7

Atoms of the same element that have different masses

Question 8

Mass number

Answer 8

Total number of protons and neutrons that make up the nucleus of an isotope

Question 9

Nuclide

Answer 9

General term for a specific isotope of an element

Question 10

Atomic mass unit

Answer 10

1/12 the mass of a carbon-12 atom

Question 11

Average atomic mass

Answer 11

The weighted average of the atomic masses of the naturally occurring isotopes of an element

Question 12

Mole

Answer 12

The amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon 12

Question 13

Avogadro’s number

Answer 13

6.022 1415 x 10^23

The number of particles in exactly one mole of a pure substance

Question 14

Molar mass

Answer 14

The mass of one mole of a pure substance