Electrons have fixed energies. Electrons move around the nucleus in shells (or energy levels) - the further away a shell is from the nucleus the higher its energy.
There are sub-shells that have slightly differing energies.
Each sub-shell consists of a different number of orbitals (the bit of space where an electron moves).
Each orbital can hold up to 2 electrons, if there are 2 then they spin in opposite directions (spin-pairing).
Electrons fill shells singularly before pairing up.
Cu and Cr will donate one of their 4s electrons to the 3d sub-shell as they are happier to have a full or half full 3d block as they are more stable.
Electronic structure can be used to determine the properties of an element. Eg s block elements losing their electrons in their outer shell to become a positive ion.
Elements have an oxidation of 0.
The oxidation of a simple ion is the same as it's charge.
Transition metals have variable oxidation states.
The overall oxidation state of a compound is the same as it's overall charge.
The sum of the oxidation state of a neutral compound is 0.
Oxidation of oxygen is -2.
Hydrolysis - Reactions involving the addition of water. (splitting by water).
Nucleophile - A reagent that forms a bond with it's reaction partner by donating a both bonding electrons. (has a lone pair to donate). It is attracted to areas dense in electrons.
Substation - A reaction where an atom or group of atoms is replaced by another atom or group of atoms.
Halogenalkanes can undergo nucleophilic substitution.
Electrophile - Is a positive ion or molecule with a partial positive charge.
That will be attracted to a negatively charged region.
And will react by accepting a lone pair of electrons to form a covalent bond.