Question

Describe how the ionization energies of main group elements vary across a period in the periodic table, using a diagram if necessary.

a, Write the equation for the first ionization of potassium

Answer 1

Ionization energy refers to the amount of energy required to remove the outermost electron or the most loosley bound electron from the atom. The most common form is

When ever ionization energies are used the substance is present in gaseous state.

There are few factors which effect the ionization enery of a atom:

1. Charge on nucleus : If charge of nucleus if more the more attraction force it exerts on the outer most electron which in turn requires more amount of energy to remove the electron.

2. Distance of electron from the nucleus: If electron is present far away from the nucleus less amount of attraction force is present which requires less amount of force and vice versa.

3. number of electrons between outer electrons and nucleus: the electrons between nucleus and outer electrons scrren the amount of force exerted on the outer electron.

Consider elements across a period in a periodic table. As we move along the period the size of the atom decreases continuously which results in increase in amount of energy spent to remove the loosely bound electron.

This graph gives you a idea of how it varies across a period:

2. Equation for the first ionization of potassium looks like this:

K_(g) → K⁺_(g) + e^-

Energy required = 419 KJ/mol