IB chemistry HL: 2.1 - Ionic configuration

shorter because most things have been already covered in GCSES

latice enthalpy

a measure of the strength of the electrostatic attraction between ions in an ionic compound.

• The larger the lattice enthalpy the stronger the ionic bond.

• The lower the lattice enthalpy the weaker the ionic bond.

Things which affect strength of ionic bond

• lattice enthalpy

• ionic radius

• charge

Ionic bonding definition

a bond made by the electrostatic attraction between two oppositely charged ions

when molecules get dissolved in water and become ions

they get Ionised in water and can conduct electricity.

effect of radius of ion on strenght of attraction

the larger the radius of the ion, the weaker the ionic bond. This is because of the greater distance between the two ions as the radius increases, weakening the electrostatic attraction.

effect of charge of ion on strength of attraction

the greater the charge of the ion, the greater the electrostatic attraction

the structure of ionic bonding

Ionic compounds form a three-dimensional lattice structure.

melting point of salts and why is it like that

very high melting points as melting them involves breaking strong electrostatic bonds between the oppositely charged ions in the lattice structure which requires a lot of energy

volatility salts

As ionic compounds have high melting points and do not easily vaporise they have a low volatility.

solubility of salts

• the water molecules interact with the salts they are polar

• if the ion dipole attraction is strong enough, the attractive forces in ionic compounds can be overcome

Conductivity of salts

• Solid ionic compounds have cations and anions as charged particles that are fixed in the crystal lattice. This lattice structure in the solid state prevents movement of the charged ions. Therefore, solid ionic compounds are not electrically conductive.

• When an ionic compound melts to form a molten liquid, the ionic bonds holding oppositely charged ions begin to break. This allows cations and anions to move throughout the liquid. Since there is motion of charged particles, molten ionic compounds are electrically conductive.

• When an ionic compound dissolves in water to form an aqueous solution, ions are surrounded by water. Since ions are no longer fixed in positions (as they were in the solid lattice) they are free to move throughout the solution. As there is motion of charged particles, aqueous ionic compounds are electrically conductive. 

brittleness salts

• When a stress is applied (caused by dropping or hitting with a hard object), layers within the lattice shift in response to that stress.

• As layers shift, ions become adjacent to like charges.

• These like charges experience an electrostatic repulsion and layers separate from one another, which forces the lattice to break into pieces.

• This is why ionic compounds, like sodium chloride in table salt, are brittle.

process in which ion becomes an atoms again

discharged