Electrons & ionisation energy

give the number of electrons that can fill the first four shells

2, 8, 18, 32

define atomic orbital

a region around the nucleus that can hold up to two electrons with opposite spins

give the shapes of s and p orbitals

In an s-orbital the electron cloud is within the shape of a sphere, In a p-orbital the electron cloud is within the shape of a dumb-bell

state the number of orbitals and electrons in s, p and d sub-shells

s- 1 orbital per shell with 2 electrons

p- 3 orbitals from shell two with 6 electrons

d- 5 orbitals from shell three with 10 electrons

state the rules for filling orbitals

fill the lowest energy orbitals first, orbital can hold a maximum of 2 electrons and they must have opposite spins, electrons will fill empty orbitals first before pairing up

say how to write a Noble gas electronic configuration

Argon- 1s2, 2s2, 2p6, 3s2, 3p6

define first ionisation energy

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

define successive ionisation energy

the second ionisation energy will be greater than the first because after the first electron is lost the other electrons are pulled closer to the nucleus meaning the nuclear attraction on the remaining electron increase and more ionisation will be needed to remove the second electron

describe the trend in ionisation energy down a group linked to atomic radius, electron shielding and nuclear attraction

down the group the atomic radius increases so there is more shielding and less nuclear attraction to the outer electron decreasing the first ionisation energy

describe the trend in ionisation energy across a period linked to atomic radius, electron shielding, nuclear charge and nuclear attraction

Across a period the nuclear charge increases so the atomic radius decreases meaning the nuclear attraction to the outer electron is greater increasing the first ionisation energy

explain how to find the identity of an element using successive ionisation energies

look for the largest sudden jump in successive ionisation energy values, this jump reveals that an electron is being removed from a new inner shell closer to the nucleus. Count the number of electrons removed before the big jump. This equals the number of outer electrons, look at the periodic table group numbers.