Successive Ionisation Energies and Electron Configurations (Vocabulary Flashcards)

A set of vocabulary flashcards covering key terms related to successive ionisation energies and electron configurations.

First ionisation energy

The energy required to remove one electron from a neutral gaseous atom in its ground state to form a 1+ ion.

Second ionisation energy

The energy required to remove a second electron after the first has been removed (to form a 2+ ion).

Successive ionisation energies

The sequence of energies required to remove electrons one by one from an atom; large jumps indicate removal from shells closer to the nucleus.

Shielding

The repulsion by inner electrons that reduces the attraction between the nucleus and outer electrons.

Effective nuclear charge (Zeff)

The net positive charge experienced by outer electrons after shielding by inner electrons is taken into account.

Outer (valence) electrons

Electrons in the outermost shell that determine chemical properties and ionisation trends.

Inner shells

Electrons in shells closer to the nucleus that shield outer electrons from the full nuclear charge.

Electron configuration

The arrangement of electrons in an atom described by shells and subshells (e.g., 1s2 2s2 2p6 3s1).

Shell

An energy level labelled by the principal quantum number n (e.g., n=1, n=2, n=3) where electrons reside.

Principal quantum number

The number n that labels a shell's energy level (distance from the nucleus).

Sub-shells (s, p, d)

Divisions within a shell where electrons reside; each sub-shell (s, p, d) has a characteristic shape and capacity.

Spin-pair repulsion

Repulsion between paired electrons in the same orbital, which can affect the energy required to remove an electron.

Log10 ionisation energy

The base-10 logarithm of the ionisation energy, used to plot and interpret ionisation-energy graphs.

Pattern: IE1 increases across a period

Across a period, IE1 generally rises because nuclear charge increases while shielding remains similar and the outer electron stays in the same shell.

Pattern: drop between periods

A sharp decrease in IE1 when moving from the end of one period to the next, since the outer electron enters a higher energy shell farther from the nucleus.

Pattern: Be to B decrease (IE1)

A slight decrease in IE1 from Be to B in the same period due to occupancy of a higher-energy 2p sub-shell (Be: 2s2; B: 2s2 2p1).

Pattern: N to O decrease (IE1)

A slight decrease in IE1 from N to O in the same period due to spin-pair repulsion in the 2p orbital with paired electrons.

d-block disruption

In Period 4, the presence of d-block elements disrupts the simple IE1 trend because their IE1 values are relatively high and similar.

Group

A vertical column of the periodic table; elements in the same group have the same number of outer electrons.

Period

A horizontal row of the periodic table; elements in the same period have the same number of electron shells.

State symbols

Symbols (s, g, l, aq) indicating the physical state of a species in a chemical equation.

Aluminium (Al) electron configuration

1s2 2s2 2p6 3s2 3p1 (Z=13).

Aluminium ion Al3+ electronic configuration (1s notation)

1s2 2s2 2p6 (i.e., the electron arrangement corresponds to [Ne]).

Magnesium electron configuration

1s2 2s2 2p6 3s2.

Three electron shells in aluminium

Graphical evidence from successive ionisation energies showing distinct steps corresponding to three shells.

5th ionisation energy

Energy required to remove the fifth electron in the successive ionisation sequence; typically much larger when crossing into an inner shell.

Argon (Ar) electron configuration (1s notation)

1s2 2s2 2p6 3s2 3p6.

Sodium electron configuration

1s2 2s2 2p6 3s1.

Fluorine vs iodine IE1

Fluorine has a higher first ionisation energy than iodine because its outer electron is held more tightly (smaller atomic radius and less shielding) despite iodine having more protons.

Graph of log10 IE vs electrons removed

A plot used to visualize shell structure by showing plateau-like regions and sharp rises as electrons are removed.