Lecture 9 ionic bonds

Bonding

Chemical or physical bonds

Chemical bonding is

intramolecule forces

physical bonding is

intermolecule force

physical bond occurs

between covalent molecules only

chemical bonds -4

ionic,colavent,dative,metallic

physical bonds-3

london forces, permanent dipole dipole, hydrogen bond

weakest physical bond

london forces

medium physical bond

Permanent dipole dipole

Strongest physical bond

Hydrogen bond

Ionic bonding can either be

Perfect ionic bonding or polarized ionic bonding

Perfect ionic bonding

There is a complete separation of charge

Polarized ionic bonding

Some of the electrons charge on the anion is pulled back towards the cation

define polarisation

Polarization is how distorted the cation causes on the anions electron cloud

The more polarizing power of the positive ion

The more the negative ion is distorted in shape

The larger the anion

The easier to be distorted

The smaller the cation

The stronger the polarizing power

The extent of polarization depends on

How much the cation pulls the electron cloud and how the anion allows the election cloud to be pulled away

Factors which increase polarization -1

Increase charge on cation or anion

Factors which increase polarization - 2

Increase size of anion

Factors which increase polarization-3

Decrease size of cation

Low polarization

Low charge, small anion, large cation

High polarization

High charge, large anion, small cation

We can prove the presence of ions by -1

Migration of ions on a wet filler paper

We can prove the presence of ions by - 2

Electron density map

The experiment, when you electrolyze a green solution of copper (11) chromate (VI)

The filter paper turns blue at the cathode and yellow at the anode

Why does the filter paper at the cathode turn blue

As cu2+ copper ions are blue in solution

Why does the filter paper turn yellow at the anode

As the chromate ions are yellow in solution

Why is copper (11) chromate (VI) green

As it contains blue cuz+ ions and yellow chromate ions

When current is passed through the solution

As the positive ions of cu2+ will go to the cathode and the negative chromate ions will go to the anode

Election density map

The electron density map of an ionic crystal, shows that there are spaces between the ions, where the density of electrons is zero. This shows there is no shared electrons

How to make electron density map

By using X-ray crystallography, a beam of X-ray is fired at a crystal and the electrons in the crystals scatter the X-rays

The pattern of scattering gives

A picture of electron through the crystal