Question

The successive ionization energies for element X is given below
IE1=250 kj mol^-1
IE2=820 kj mol^-1
IE3=1100 kj mol^-1
IE4=1400 kj mol^-1
Find out the number of valence electrons for the element X

Answer 1

answer : number of Valence electrons for the element X = 1

explanation : before going to check out ionisation energies of given element. let's understand what is the meaning of ionisation energy.

“ it is the amount of energy required to remove an electron from an isolated gaseous atom. ”

it is easy to understand, ionisation energy will be lower in value, when we remove an electron from an outermost shell (known as valence shell) which has unstable configuration.

if an element has successive ionisation energies are I.E1 , I.E2 , I.E3 ....

in such a way that,

I.E1 < (I.E2 - I.E1),

then, definitely valency of element is 1. [ because if we assume valency of element is 1 , then after removing an electron , made ion has stable configuration which has require lot of energy to remove another element. that's why (I.E2 - I.E1) > I.E1 ]

here same case is appear.

I.E1 = 250 , (I.E2 - I.E1) = (820 - 250) = 570

i.e., (I.E2 - I.E1) > I.E1

so, valency of element is 1.

hence, number of valence electron for the element X is 1.

Answer 2

Answer:

valence is 4

Explanation:

I know u r getting confused.

here 4 electrons are removed so the valence is 4. but if they ask most common valence its 1. bcuz ionisation enthalpy is drastically increasing for 2nd one onwards.