Chapter U1, Problem 4STP

Interpretation Introduction

Interpretation:

The statement that correctly describes the electrons in carbon needs to be determined.

Concept introduction:

Atoms are composed of fundamental subatomic particles; protons, neutrons and electrons and are characterized by atomic mass (A) and atomic number (Z)

$\begin{array}{l}\text{Atomic mass = number of protons + number of neutrons ---------(1)}\\ \text{Atomic number = number of protons = number of electrons -----(2)}\end{array}$

The atomic structure or electronic structure of an element depicts the arrangement of electrons around a positively charged nucleus.

Electrons are arranged in shells and filled successively based on the Aufbau principle.The outer most electrons are known as the valence electrons.

Answer to Problem 4STP

C) Carbon has a core similar to He atom but carbon has 4 valence electrons.

Explanation of Solution

Carbon belongs to group IV A in the periodic table with an atomic number, Z = 6

Based on the Aufbau principle in the ground state of an atom, the electrons are arranged such that they occupy the lowest energy levels first. The orbitals are in the order of increasing energy as follows:

1s 2s 2p 3s 3p 4s 3d 5p…..

The ‘s’, ‘p’ and ‘d’ orbitals can hold 2, 6 and 10 electrons respectively. Thus, the electronic configuration of carbon (C) is:

$\text{C }\left[\text{Z=6}\right]{\text{ = 1s}}^{\text{2}}{\text{2s}}^{\text{2}}{\text{2p}}^2$

Similarly, the electronic configuration of helium (He) with atomic number Z = 2 is:

$\text{He }\left[\text{Z=2}\right]{\text{ = 1s}}^{\text{2}}$

Thus, carbon (C) has a core similar to He with 2 electrons in the 1s orbital. Hence the electronic configuration of C can be represented as:

$\text{C }\left[\text{Z=6}\right]{\text{ = [He]2s}}^{\text{2}}{\text{2p}}^2$

Conclusion

Therefore, carbon has a core similar to He atom and has 4 valence electrons.