Chemistry Chapter 3 Vocab

Law of Conservation of Mass

the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes

law of definite proportions

a given compound always contains exactly the same proportion of elements by mass

Law of Multiple Proportions

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

Atom

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

atomic number

the number of protons in the nucleus of an atom

Isotope

Atoms of the same element that have different numbers of neutrons

mass number

the sum of the number of neutrons and protons in an atomic nucleus

atomic mass unit

one twelfth the mass of a carbon-12 atom

average atomic mass

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

Avogadro's number

number of representative particles in a mole, 6.02 X 10^23

molar mass

the mass of one mole of a pure substance

Mole

the SI base unit used to measure the amount of a substance; Avogadro's number of things