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Bonding (Polarity (Bonds (Polar covalent bonds: When a pair of electrons…
Bonding
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Born-Haber Cycles
Enthalpy Changes
Electron affinity is when 1 mole of gaseous atoms is converted to 1 mole of gaseous ions with a single negative charge.
X + e- → X- + energy
Atomisation energy is when 1 mole of gaseous atoms is formed from the element under its standard state conditions.
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Ionisation energy is when 1 electron is removed from each atom in 1 mole of gaseous atoms.
X(g) → X+(g) + e-
Formation energy is when 1 mole of a compound is formed from its constituent elements under standard conditions, all reactants and products in their standard states.
Formation of an Ionic Bond: When an atom transfers (an) electron(s) to another atom to form ions. Loss/Gain of electrons.
Why is the formula MgCl2 and MgCl? Because Mg has a 2+ charge and Cl has a 1- charge, meaning that Mg needs 2 electrons to form a full outer shell whereas Cl needs to give 1 electron to have a full outer shell. Therefore, 2 Cl atoms are required to covalently bond with Mg for all of them to have full outer shells. Plus, MgCl2 is more stable than MgCl as it has less energy and is more negative (exothermic reaction).
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Polarity
Polarity of bonds based on electronegativity value differences:
Ionic = 2-4
Polar covalent = 1-2
Non-polar covalent = 0
Bonds
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Ionic bonds: When 1 atom is a lot more electronegative than the other, causing the pair of electrons to be completely attracted to it.
Dative covalent bonds: When 1 pair electrons coming from the same atom is shared between 2 atoms. It is shown as an arrow going from atom giving the electrons to atom receiving the electrons eg. eg. ammonia contains a lone pair of electrons which a coordinate bond is formed between a H+ ion that has no electrons, forming ammonium. 
Non-polar covalent; Polar covalent; Ionic
Existence of Ions
Electrolysis of Copper (II) Chromate (II) (CuCrO4): The solution was originally green which then the solution around the negative electrode (cathode) turned blue whereas the solution around the positive electrode (anode) turned yellow. This is because the charge of Cu is 2+ which means that it moves towards the negative electrode. Whereas the charge of CrO4 is 2- which means that it moves towards the positive electrodes.
Electron density maps are used to predict which molecules or atom could fit in that region of electron density.
Ion Polarisation: When the anion is larger than the cation, causing a distorted bond as the electron cloud of the anion is drawn to the cation.
Factors Affecting IP
Cation
Ionic charge: The higher the charge, the more polarising the cation as there is a stronger attraction for the outer electrons.
Ionic radius: The smaller the radius, the more polarising the cation as the electrons are closer to the nucleus, increasing the electrostatic attraction.
Anion
Ionic radius: The larger the radius, the easier it is to be polarised as the electrons are further from the nucleus.