periodicity
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what is periodicity
a repeating pattern across different periods
define first ionisation energy
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+ ion
why is there a sharp and slight increase in successive ionisation energies
slight increase- removing an electron means smaller atomic radius so stronger attraction sharp increase- a new shell, less shielding and smaller atomic radius so stronger attraction
why do electronegativity and ionisation energy decrease down a group
increased atomic radius and more shells so more sheilding and less attraction so easier to remove an electron increase sheilding and atomic radius outweighs the increase in nuclear charge
why does electronegativity and ionisation energy increase across a period
greater nuclear charge and smaller atomic radius so greater attraction so harder to remove an electron sheilding stays same
why is borons first ionisation energy less than berylliums
p orbital electron in boron has a higher energy than s orbital electron in beryllium so easier to remove so less energy is needed to remove it
why is oxygens first ionisation energy less then nitrogens
in the 2p orbital of oxgen two of the electrons are paired so repel making it easier to remove
what is a metallic bond
strong electrostatic attraction between cations and delocalised electrons
what 3 things are metallic bonds affected by
number of protons number of delocalised electrons number of shells
why are metal malleable
layer of cationcan easily slide over each other
give 3 examples of giant covalent molecules
diamond graphite silicon dioxide
factors that affect ionisation energy and electronegativity
nuclear charge atomic radius electron sheliding