Factors Influencing Ionisation Energy

Vocabulary flashcards covering the four primary factors that influence ionisation energy and their general trends as described in the lecture notes.

Nuclear charge

The size of the positive charge in the nucleus which increases as the atomic number (number of protons) increases, increasing the attractive force on electrons.

Distance of outer electrons from the nucleus

A factor where the force of attraction decreases as the distance between positive and negative charges increases, leading to lower ionisation energy in further shells.

Shielding

The effect where full inner shells of negatively charged electrons repel outer electrons, preventing them from feeling the full nuclear charge.

Spin-pair repulsion

The phenomenon where electrons in the same atomic orbital in a sub-shell repel each other more than electrons in different orbitals, making it easier to remove an electron.

Relationship between proton number and ionisation energy

In general, ionisation energy increases as the proton number increases because the bigger the positive charge, the greater the attractive force on electrons.

Relationship between shielding and ionisation energy

In general, ionisation energy is lower as the number of full electron shells between the outer electrons and the nucleus increases.

Ionisation energy measurement unit

The unit of measurement for the energy required to remove an electron, expressed as $kJ\,mol^{-1}$.