Atomic Structure and Mass Spectrometry Flashcards

Vocabulary practice flashcards covering fundamental concepts in atomic structure, history of the atom, mass spectrometry, electronic configurations, and ionisation energy trends.

Atomic Number ($Z$)

The number of protons in the nucleus of an atom.

Mass Number ($A$)

The total number of protons and neutrons in an atom.

Plum-pudding Model

An early model of the atom suggesting that the atom was a ball of positive charge with negative electrons embedded in it.

Nuclear Model

A model of the atom proposed after alpha scattering experiments, where the centre is a positively charged nucleus containing most of the atom's mass, with electrons orbiting it like planets around the sun.

Bohr Model

An adaptation of the nuclear model proposed by Neils Bohr, suggesting that electrons orbit the nucleus at specific distances on energy levels or shells.

Isotopes

Atoms with the same number of protons, but different numbers of neutrons.

Electron Impact Ionisation

An ionisation technique where a vaporised sample is injected at low pressure and an electron gun fires high energy electrons at it to knock out an outer electron, forming positive ions.

Electrospray Ionisation

An ionisation technique where a sample is dissolved in a volatile, polar solvent and injected through a fine needle at high voltage, causing the molecule $M$ to gain a proton and form $MH^+_{(g)}$.

Parent Ion

The peak with the largest m/z ratio in an electron impact mass spectrum, which is caused by the complete unfragmented molecule and is equal to its relative molecular mass ($M_r$).

Atomic Orbital

A region within a sub-level that holds up to 2 electrons of opposite spin, representing the mathematical probability of finding an electron within certain spatial distributions around the nucleus.

s-Block Element

An element whose outer electron is filling an s-subshell, such as sodium ($1s^2 2s^2 2p^6 3s^1$).

First Ionisation Energy

The enthalpy change when one mole of gaseous atoms forms one mole of gaseous ions with a single positive charge, represented by $H_{(g)} \rightarrow H^+_{(g)} + e^-$.

Second Ionisation Energy

The enthalpy change when one mole of gaseous ions with a single positive charge forms one mole of gaseous ions with a double positive charge, represented by $Ti^+_{(g)} \rightarrow Ti^{2+}_{(g)} + e^-$.

Periodicity

A repeating pattern of physical and chemical properties of elements across a period on the periodic table.

Shielding

The effect where an electron in an outer shell is repelled by electrons in complete inner shells, weakening the electrostatic attraction of the nucleus.