definitons for everything - 3/1/26

Relative isotopic mass

• Mass of an atom of an isotope

• compared with 1/12 of the mass

• of an atom of carbon-12

Relative atomic mass

• weighed mean mass

• Of an Atom

• Of an element

• Compared with 1/12 of the mass

• Of an atom of carbon-12

Amount of substance

Number of moles

• counting atoms?

Mole

The amount of substance

Containing as many particles

As there are carbon atoms

In 12g

Of carbon-12 isotope

Avogadros constant

The number of particles

Per mole of a substance

6.02×10²³

Molar mass

Mass per mole

Of a substance

Same as RFM

Empirical formula

The simplest whole number ratio

Of atoms of each element

Present in a compound

Molecular formula

The number and type

Of atoms of each element

In a molecule

What does .xH2O show

water of crystallisation

Not number of moles of water

Electronegativity

The ability of an atom

To attract the bonding electrons

In a covalent bond

Periodicity

The repeating pattern in physical and chemical properties across periods

First ionisation energy

The removal of one mole of electrons

From one mole of gaseous atoms