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Flashcards in module 2 Deck (10):

first ionisation energy

energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions


electron shielding

the repulsion between electrons in different inner shells. shielding reduced net force from the positive nucleus on the outer shell electrons.


successive ionisation energies

a measure of the energy required to remove each electron in turn


factors affecting ionisation energy

atomic radius: the greater the atomic radius the smaller the nuclear attraction experienced by the outer electrons.

nuclear charge: the greater the nuclear charge, the greater the attractive force on the outer electrons

electron shielding. screening: inner shells repel the outer-shell electrons. the more inner shells there are the larger the shielding effect and the smaller the nuclear attraction experienced by the outer electrons.


each successive ionisation energy is larger than the one before...why ?

- as each electron is removed, there is less repulsion between the electrons and each shell will be drawn in closer to the nucleus.
-as the distance from each electron from the nucleus decreases slightly, the nuclear attraction increases. More ionisation energy is needed to remove each successive electron.


how can successive ionisation energies provide evidence for the presence of shells?

as you see the successive ionisation energies, when there is a large increase in the energy required you know that an electron must have been removed from a different inner shell. This because there is far less electron shielding when a new shell is uncovered.



a group of orbitals with the same principal quantum number, also known as main energy levels


principal quantum numbers

a number representing the relative overall energy of each orbital, which increases with distance from the nucleus. The sets of orbitals with the same n-value are referred to as electron shells.


atomic orbital

a region within an atom which can hold up to two electrons with opposite spins


sub shell

a group with the same type of atomic orbitals (s,p,d or f) within a shell