Atomic radius: Distance from the nucleus to the outermost electrons of the atom
Ionic radius: Distance from the nucleus to the outer shell electrons in an ion.
- Both decreases across the period, increases down the group
First ionization energy: The minimum energy required to remove a valence electron from a gaseous atom
- Increases across the period, decreases down the group
Electronegativity: The ability of an atom/nucleus to attract a pair of electrons in a bond.- Metals: Electrophobic / Non-metals: Electrophilic
- Increases across the period, decreases down the group
- bonding electrons are furthest from the nucleus —> reduced attraction
Electron affinity: The change in energy (heat) when one mole of electron is added to one mole of gaseous atoms to form 1 mole of gaseous ion.
- Increases across the period, decreases down the group
- X(g) + e– → X–(g) - Exothermic reaction in general, but >second electron affinity is endothermic because the added electron is repelled by the negatively charged ion. —> energy required
Melting point: based upon their bonds.
- Metals: Metallic bonding (delocalized electrons attracted to cations)
- M.P. decreases down the group due to electrons further away from the nucleus
- Covalent compounds: London (dispersion) force
- M.P. increases down the group due to more frequent London (dispersion) forces