Q1 of 8 Page 25

Which are the subshells in which electrons are filled in the s block elements of the third period? Write the subshell electronic configuration of the last element of this period.

The subshells in which electrons are filled in the s block elements of the third period are 1s,2s,2p,3s.

18Ar– 1s2 2s2 2p6 3s2 3p6


The s block elements of the third period are Na and Mg. So 1s,2s,2p,3s are the subshells in which electrons are filled.


The last element of third period is Argon which has atomic number 18.



More from this chapter

All 8 →
1

Which are the subshells in which electrons are filled in the s block elements of the third period? Write the subshell electronic configuration of the last element of this period.

 2

When the last electron of an atom was filled in the 3d subshell, the subshell electronic configuration was recorded as 3d8. Answer the questions related to this atom.

• Complete subshell electronic configuration


• Atomic number


• Block


• Period number


• Group number

 3

Pick out the wrong ones from the subshell electronic configurations given below.

a) 1s2 2s2 2p7


b) 1s2 2s2 2p2


c) 1s2 2s2 2p5 3s1


d) 1s2 2s2 2p6 3s2 3p6 3d2 4s1


e) 1s2 2s2 2p6 3s2 3p6 3d2 4s2

 4

The element X in group 17 has 3 shells. If so,

a) Write the subshell electronic configuration of the element.


b) Write the period number


c) What will be the chemical formula of the compound formed if the element X reacts with element Y of the third period which contains one electron in the p subshell?