Chemistry: Moles, Molar Mass, and Mass Spectra 1.1 - 1.2

Vocabulary flashcards covering the concepts of molecular weight, the mole, molar mass, and mass spectrometry based on Topics 1.1 and 1.2 of the lecture notes.

Molecular weight (or Formula Weight)

The sum of the atomic weights of the atoms in the chemical formula of a substance, expressed in atomic mass units ($amu$).

Molar Mass

The mass of one mole of a substance in grams ($g/mol$); it is numerically equal to the substance's molecular weight in $amu$ but allows for conversions between moles and grams.

Mole

A unit used to 'scale up' from atomic mass units to real-world quantities in grams, where 1 mole of particles weighs the same in grams as one single particle weighs in $amu$.

Hydrate

A compound that attracts and absorbs water; its molar mass calculation must include the mass of the water bound to the compound (e.g., $FeCl_3 \cdot 6H_2O$).

Avogadro’s Number

$6.022 \times 10^{23}$ particles/mole; the conversion factor used to move between the number of particles (atoms, molecules, ions) and the number of moles.

Mass Spectrometer

A device that provides information on the number of isotopes present, the atomic mass of each isotope, and the relative amount (percent abundance) of each isotope.

Mass Number

A whole number that is approximately equal to the atomic mass of a single atom, calculated by the sum of its protons and neutrons.

Average Atomic Mass

The relative atomic mass of an element calculated from the masses and relative abundances of all its naturally occurring isotopes as provided by mass spectrometry data.

Isotopes

Atoms of the same element that have different masses; they are represented by individual peaks on a mass spectrum.