Question

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What period 3 element having the following ionization energies (all in kJ/mol)?

IE1 = 1012, IE2 = 1900, IE3= 2910, IE4= 4960, IE5= 6270, IE6 = 22,200

A) Si            B) S                 C) P                 D) Cl               E) Mg

2)

Which reaction below represents the electron affinity of Li?

A) Li(g) + e⁻ → Li⁻(g)

B) Li(g) → Li⁺(g) + e⁻

C) Li(g) + e⁻ → Li⁺(g)

D) Li⁺(g) → Li(g) + e⁻

E) Li⁺(g) + e⁻ → Li(g)

Answer 1

(1) In the set of given ionization energies

IE1 = 1012, IE2 = 1900, IE3= 2910, IE4= 4960, IE5= 6270, IE6 = 22,200

There is a sudden jump (drastic) from IE5 to IE6 this indicates that after removing 5 electrons the element is more stable.So from this most stable ion the energy spent to remove an electron requires more energy.

Therefore the element must have 5 valency electrons in its outer shell, this can be possible with P ( 15th group element), so the correct option is (C) P

(2) Electron affinity is defined as the change in energy (in kJ/mole) of a neutral atom (which is in the gaseous phase) when an electron is added to the atom to form a negative ion.

So the Electron affinity of Li is Li(g) + e⁻ → Li⁻(g)

Therefore option (A) is correct