Question

A) Write the equation for the fifth ionization energy of phosphorous. B) Using the ionization energies for silicon below, please explain why the ionization energies increase. 1E5 E. (kJ/mol) Element Ez (kJ/mol) |E2 (kJ/mol) IE3 (kJ/mol) |E4 (kJ/mol) (kJ/mol P 1012 1907 2914 4964 6274 21267 C) Why is there a large increase in energy from the fifth ionization energy to the sixth ionization energy?

Answer 1

1) fifth ionisation energy will be

E = I.E (1) + I.E(2) +I.E(3)+ I.E(4)+I.E(5)

The chemical equation will be

P​​​​​4+ $\rightarrow$ P​​​​​5+ + e​​​​​​-

it will be the summation of all ionisation energies for phosphorus.

2) when an electron is taken out of an atom, it makes the atom positively charged. This means there will be one electron less but the number of proton will remain the same. Thus attraction force per electron increased if one electron gets out. Thus more the attraction force towards nucleus , means less easy to extract next electron and thus more the energy required and so more the ionisation energy. This goes on for next electron.

3) table data is given for phosphorus.

electronic configuration of phosphorus is

1s22s2 2p6 3s2 3p3

After 5th ionisation energy,

Configuration would be

1s22s2 2p6

now this is most stable configuration of a period. This is fully filled noble gas configuration. Which means pulling out electron is not easy from this configuration. That is why it requires huge amount of energy to pull out another electron after the fifth one.