Magnesium bromide is a (an) _____ compound.

1. Intermolecular forces:

(i) Intermolecular forces are the forces existing among the molecules of any substance. These can be dipole-dipole (forces act between the molecules possessing permanent dipole), ion-dipole, ion-induced dipole, dipole-induced dipole (e.g., between any polar molecule and a noble gas), dispersion or London forces (between any two non-polar molecules due to formation of a momentary dipole and an induced dipole) and hydrogen bonding.

(ii) Dipole-dipole, dipole-induced dipole and dispersion forces are collectively called van der Waals forces.

2.  Chemical bonding:

(i) The force which holds the atoms together in a molecule is called a chemical bond.

(ii) Atoms combine so as to complete their octets ($8$ electrons in the outermost shell) or duplet ($2$ electrons in the outermost shell) in case of $\mathrm{H}, \mathrm{Li}, \mathrm{Be},$  etc. to attain nearest noble gas configuration and gain stability.

(iii) Atoms combine by:

(a) By transference of electrons from one atom to another (ionic bond/electrovalent bond)

(b) By mutual sharing of electrons (covalent bond)

(c) By sharing of electrons contributed by one atom (coordinate bond/dative bond)

3. Hydrogen bond:

(i) Hydrogen bonding describes the interaction between a hydrogen atom and another very electronegative atom to produce unusually strong dipole-dipole forces. Two types of hydrogen bonds are formed: intermolecular and intramolecular hydrogen bonds.

(ii) Intermolecular hydrogen bond occurs between different molecules, Intramolecular hydrogen bond occurs within the same molecule.

(iii) Many compounds show unusual properties due to hydrogen bonding such as density, melting and boiling points.

4. Valence Shell Electron Pair Repulsion (VSEPR) theory

(i) It states, “Electron pairs surrounding the central atom repel one another and go far apart from one another until there are no further repulsions.”

(ii) The magnitude of repulsions is: Lone-Pair-Lone Pair $>$ Lone Pair-Bond Pair $>$ Bond Pair-Bond Pair.

(iii) If central atom is linked to similar atoms and there are no lone pairs, the shape is symmetrical (regular) otherwise irregular. If A represents central atom, $\mathrm{B}$ bond pair and L lone pair, we have ${\mathrm{AB}}_2$ (linear), ${\mathrm{AB}}_3$ (triangular planar), ${\mathrm{AB}}_4$ (tetrahedral), ${\mathrm{AB}}_2\mathrm{L}$ (V-shape), ${\mathrm{AB}}_2{\mathrm{L}}_2$ (bent), ${\mathrm{AB}}_3\mathrm{L}$ (trigonal pyramidal), ${\mathrm{AB}}_3{\mathrm{L}}_2$ (T-shape), ${\mathrm{AB}}_2{\mathrm{L}}_3$ (linear), ${\mathrm{AB}}_5$ (trigonal bipyramidal), ${\mathrm{AB}}_4\mathrm{L}$ (see-saw), ${\mathrm{AB}}_6$ (octahedral), ${\mathrm{AB}}_5\mathrm{L}$ (square pyramidal), and ${\mathrm{AB}}_4{\mathrm{L}}_2$ (square planar).

5. Types of covalent bonds:

When the overlap takes place along the internuclear axis, the bond formed is called sigma $\left(\sigma \right)$ bond. It can be $\mathrm{s}–\mathrm{s}, \mathrm{s}–\mathrm{p}$ or $\mathrm{p}–\mathrm{p}$ overlap. When a covalent bond is formed by sideways overlapping of orbitals, it is called pi $\left(\pi \right)$ bond, e.g., between $\mathrm{px}$ and $\mathrm{px}$ or $\mathrm{py}$ and $\mathrm{py}$ orbitals. $\sigma$-bond is always stronger than $\pi$-bond because overlapping is greater along the internuclear axis than sideways overlapping.

6. Fajan's rule and polarisation:

(i) Fajan's rule states that if two oppositely charged ions are brought together, the nature of the bond between them depends upon the effect of one ion on the other.

(ii) Covalent bond formed between two dissimilar atoms is called a polar bond. A covalent bond formed between two similar atoms is called a non-polar bond.

7. Hybridisation:

Mixing of atomic orbitals of an atom with slightly different energies to form the same number of new orbitals of equal energy and identical shape is called hybridisation. The new orbitals formed are called hybrid orbitals.