Question

5)

(a) Using the symbol of the previous noble gas to indicate the core electrons, write the electronic configurations of atoms in the following elements: (i) Al (ii) Se (iii) P

(b) How many valence electrons are there in each of the above atoms?

(c) When the above elements form an ion, what charge is each of them likely to have?

(d) Using the noble gas notation, write the electronic configurations of the ions formed in part (c).

Answer 1

i) [Ne] 3S² 3P¹     atomic no.= 13

ii) [Ar] 3d¹⁰ 4s² 4p⁴      atomic no.= 34

iii) [Ne] 3s² 3p³    atomic no.= 15

b)   Al = 3 , Se =6, P = 5 last electron of last orbital number will valence electron

c) Al = +3 charge in ion form

Se = -2 charge in ion form

P = -3 charge in ion form

d) [Ne] 3S² 3P¹    = +3

ii) [Ar] 3d¹⁰ 4s² 4p⁴   =6-8 = -2

iii) [Ne] 3s² 3p³    =8-5 = -3