Question

Select the correct answer. An atom of nitrogen has seven electrons. Which diagram correctly represents the arrangement of these electrons? A. two blue boxes representing 1s and 2s orbitals, and one set of three blue boxes representing 2p orbitals; 1s and 2s orbitals have a pair of up and down arrows; 2p orbitals show one filled orbital with a pair of up and down arrows, a partially filled orbital with one up arrow, and an empty orbital B. two blue boxes representing 1s and 2s orbitals, and one set of three blue boxes representing 2p orbitals; 1s orbital has a pair of up-facing arrows and the 2s orbital has a pair of down-facing arrows; 2p orbitals show one filled orbital with a pair of up-facing arrows, a partially filled orbital with one down-facing arrow, and an empty orbital C. two blue boxes representing 1s and 2s orbitals, and one set of three blue boxes representing 2p orbitals; 1s and 2s orbitals have a pair of up and down arrows; 2p orbitals show three partially filled orbitals with a single up-facing arrow D. two blue boxes representing 1s and 2s orbitals, and one set of three blue boxes representing 2p orbitals; 1s orbital has a pair of up-facing arrows and 2s orbital has a pair of down-facing arrows; 2p orbitals show three partially filled orbitals with one up-facing arrows in two of the orbitals and one down-facing arrow in the third

Answer 1

Answer:

C. two blue boxes representing 1s and 2s orbitals, and one set of three blue boxes representing 2p orbitals; 1s and 2s orbitals have a pair of up and down arrows; 2p orbitals show three partially filled orbitals with a single up-facing arrow

Explanation:

This problem is concerned with the electronic distribution of electrons into the energy levels or sub-level of the atom of nitrogen. Here in particular, we want to know the sublevel arrangement of electrons in the nitrogen atom.

Nitrogen has 7 electrons.

In order to know the sequence of filling of the atoms we must be guided by some principles:

1. We must know that the maximum number of electrons in the orbitals of the sub-levels are: 2 for s-sublevel, 6 for p-sublevel, 10 for d-sublevel and fourteen for f-sublevel.
2. The sublevels with the lower energies are filled first according to the aufbau's principle: 1s, 2s, 2p, 3s, 3p...........
3. No two electrons can have the same set of values for the four quantum numbers i.e electrons cannot spin in the same direction. This is the pauli's exclusion principle.
4. Electrons go into degenerate orbitals singly before pairing starts according to Hund's rule of maximum multiplicity.

Obeying these principles, we have:

N  (7) = 1s²2s²2p³

The first blue boxes are the s-sublevels 1s²2s²  with one orbital and would have two electrons each oriented in the up and down direction.

The p-sublevel has three orbitals and according to hund's rule, electrons would go in singly before pairing starts. This leaves the three orbitals with a single up facing arrow.