module 2

Question 1

first ionisation energy

Answer 1

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

Question 2

electron shielding

Answer 2

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

Question 3

successive ionisation energies

Answer 3

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

Question 4

factors affecting ionisation energy

Answer 4

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.

Question 5

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

Answer 5

• 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.

Question 6

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

Answer 6

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.

Question 7

shell

Answer 7

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

Question 8

principal quantum numbers

Answer 8

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.

Question 9

atomic orbital

Answer 9

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

Question 10

sub shell

Answer 10

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