USCE Vocabulary List

Elements

simplest form of matter that consists of only 1 type of atom

Compounds

composed of 2 or more different elements chemically combined in a fixed ratio

Mixtures

composed of 2+ elements or components in no fixed ratio

Filtration

a physical separation process that uses a filter to separate solids from liquids or gases.

Distillation

a separation process that involves separating a liquid mixture based on differences in volatility

Solvation

a separation process that involves separating heterogenous mixtures of 2 solids based on differences in solubility

Chromatography

a separation process that involves separating components of a mixture of solutes in a solvent

Recrystallisation

a separation process that involves separating impurities mixed in with a solid

Isotopes

are atoms of the same element with different numbers of neutrons

Radioisotopes

are isotopes that have unstable nuclei

Relative atomic mass

weighted average of all naturally occurring isotopes of an element relative to carbon-12

Relative formula mass

sum of relative atomic mass of all atoms in covalent molecule or f.u of an ionic compound

Light emission spectra

a pattern of bright coloured lines that appear when atoms/molecules emit light at specific wavelengths as their electrons drop from higher to lower energy levels

Atomic orbital

describes the volume of space where there is a high probability of finding an electron

Aufbau Principle

When adding electrons to an atom, the lower energy sublevels must be filled first

Pauli Exclusion Principle

atomic orbitals only hold two electrons and they must have opposite spin

Hund’s Rule

each orbital within a given sublevel must be filled with a single electron before electrons are paired up

Ionisation energy

energy required to remove one mole of electrons from one mole of atoms in the gaseous state

Ionisation

The process of adding or removing electrons from an atom to create an ion

Convergence limit

the point in which energy levels converge (overlap)

Molar mass

mass in grams of one mole of a substance

Successive ionisation energies

energies needed to remove a series of electrons