Question

Which of the following elements has the lowest ionization energy?

A)

Argon

B)

Hydrogen

C)

Beryllium

D)

Helium

Answer 1

Lets look at EC of each element one by one

#Argon

• Z=18

Electronic Configuration given by

`\\ \sf\longmapsto 1s^22s^22p^63s^23p^6`

• Full filled orbital

#Hydrogen

• Z=1

`\\ \sf\longmapsto 1s^1`

• it is half filled.

#Berylium

• Z=4

`\\ \sf\longmapsto 1s^22s^2`

• Full filled orbital.

#Helium

• Z=2

`\\ \sf\longmapsto 2s^2`

• Full filled

Hence our answer is hydrogen.