Ionic bonding is the electrostatic attraction between positive and negative ions. Compounds such as sodium chloride (table salt) is bonded by ionic bonds. In ionic bonds, there is a transfer of electrons to achieve stable outer shells within each atom.
Metallic bonding is the electrostatic attraction between positive metal ions and delocalised electrons.
A covalent bond is a shared pair of electrons. Electrostatic forces of attraction between the nuclei of both atoms and the shared pair of electrons hold the covalent bond together. Covalent bonds can be formed by sigma or pi bonds. A dative covalent bond is when both electrons in a covalent bond come from the same atom.
Electronegativity is the ability of an atom to withdraw or pull a bonding pair of electrons in a covalent bond. Difference in electronegativity allows for the rise of intermolecular forces, as well as allowing organim mechanisms to occur.
There are 3 main types of intermolecular forces: Van der Waals, Permanent Dipole-dipole and hydrogen bonding.
Van der Waals forces occur due to instantaneous dipoles forming from unequal distribution of electrons, permanent dipole-dipole occur between 2 slighty-positive and slighty-negative atoms due to electronegative differences. Hydrogen bonding is a stronger version of permanent dipoe-dipole such that it is the electrostatic attraction between an slightly-positive hydrogen atom and a slighty-negative nitrogen/oxygen/fluorine.
Giant covalent, simple molecular, metallic, giant ionic lattice are the 4 types of crystal structures. Due to their nature of bonding,they all have different properties and boiling/melting points.
The electron repulsion theory states that electrons will try to spread out as far as possible to minimise repulsion. Lone pair of electrons repel more than bonding pair of electrons. Hence we have different types of molecular shapes depending on the amount of bonding/lone pair of electrons the molecule has.