Q3 of 8 Page 25

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

The wrong electronic configurations are a), c), d).

In a) 1s2 2s2 2p7, p subshell can have a maximum of only 6 electrons.


In c) 1s2 2s2 2p5 3s1, According to Aufbau rule electrons will be filled first in that subshell which has less energy and when less energy subshell will become full filled then after this next subshell will be filled.


In d) 1s2 2s2 2p6 3s2 3p6 3d2 4s1, here 4s subshell will be full filled first and after this 3d subshell will fill because 4s subshell has less energy than 3d subshell.


More from this chapter

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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

 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?

 5

The element Cu with atomic number 29 undergoes chemical reaction to form an ion with oxidation number +2.

a) Write down the subshell electronic configuration of this ion.


b) Can this element show variable valency? Why?


c) Write down the chemical formula of one compound formed when this element reacts with chlorine (17Cl).