Atomic Structure and Periodic Table + Definitions

Vocabulary flashcards created from lecture notes covering atomic structure, mass spectrometry, quantum rules, and periodic trends.

Isotopic Mass

The mass of an isotope relative to $\frac{1}{12}$ of a carbon-12 atom.

Relative atomic mass

The weighted mean mass of an atom relative to $\frac{1}{12}$ of a carbon-12 atom.

Relative molecular mass

The total mass for a substance, always used for simple covalent molecules.

Relative formula mass

The mass used for compounds with giant structures, such as ionic lattices.

Isotopes

Atoms in the same element with the same amount of protons but a different number of neutrons.

Orbital

Regions of space surrounding the nucleus where there is a high probability of finding an electron.

Ionisation (TOF Mass Spectrometry)

The first stage of time of flight mass spectrometry where electrons are knocked off by high-speed electron bombardment to form ions.

Acceleration (TOF Mass Spectrometry)

The second stage of time of flight mass spectrometry where an electric field gives all ions the same kinetic energy.

Ion drift (TOF Mass Spectrometry)

The third stage of time of flight mass spectrometry through a field-free tube where lighter ions travel faster and arrive first.

Detection (TOF Mass Spectrometry)

The stage where ions hit the detector, generating a measured current, and the time of flight is used to calculate $\text{m/z}$.

Electrospray ionisation

An ionisation technique used for large macromolecular structures like proteins where the sample is dissolved in a volatile polar solvent and forced through a high voltage needle; droplets pick up protons ($H^+$ ions) as solvent evaporates, leaving intact positively charged molecules without shattering.

Hund's rule

Electrons fill orbitals singly (one per orbital) before pairing up, and when paired, the 2 electrons must have opposite spins.

Pauli exclusion principle

No 2 electrons can have the same set of quantum numbers, meaning an orbital holds a maximum of 2 electrons with opposite spins.

Periodicity

A trend that is repeated across each period of the periodic table.

Factors affecting ionisation energy

1. Size of the nuclear charge. 2. Distance of outer electrons from the nucleus. 3. Shielding effect of inner electrons. 4. Spin-pair repulsion.