Chapter 5, Problem 91A

Interpretation Introduction

Interpretation:

The number of electrons, completely filled orbitals and number of orbitals with n=4 in Arsenic atom needs to be determined.

Concept introduction:

Electrons are placed in certain energy levels which are called as shell. The outermost shell of an atom is called as valence shell and the electrons are called as valence shell electrons. These valence shell electrons take part in all chemical reactions and are also involved in chemical bonding.

Answer to Problem 91A

Number of electrons = 33

Number of completely filled orbitals = 10

In 4^th shell there are total 4 orbitals in 4s and 4p.

Explanation of Solution

Given information:

Arsenic atom has n = 4 principal energy level.

Since in an atom, the atomic number of an atom is equal to the number of electrons in it, therefore, the number of electrons must be 33.

The electronic configuration of arsenic will be:

${\text{ 1s}}^{\text{2}}{\text{, 2s}}^{\text{2}}{\text{, 2p}}^{\text{6}}{\text{, 3s}}^{\text{2}}{\text{, 3p}}^{\text{6}}{\text{, 3d}}^{10}\text{, 4s², 4p³}$

There are total 6 sub-shells are completely filled:

• 1s = 1 orbital
• 2s = 1 orbital
• 2p = 3 orbitals
• 3s = 1 orbital
• 3p = 3 orbitals
• 4s = 1 orbital
• Total = 10 orbitals

In 4^th shell there are total 4 orbitals in 4s and 4p.

Conclusion

Number of electrons = 33

Number of completely filled orbitals = 10

In 4^th shell there are total 4 orbitals in 4s and 4p.