Question

1- Give the electron configurations of the following species:
He, C, O, O 2-, F -, Ne, Na+, Al, Cl, Ca, Cr, Fe, and Cu
which of the above species are isoelectronic, that is those with the same configuration?

2- What are the allowable spins, m s ?

3- How many lines are observed in the visible atomic line spectrum for the H atom

Answer 1

1) He - 1s²

C - 1s² 2s² 2p²

O - 1s² 2s² 2p⁴

O^2- - 1s² 2s² 2p⁶

F^- - 1s² 2s² 2p⁶

Ne - 1s² 2s² 2p⁶

Na⁺ - 1s² 2s² 2p⁶

Al - 1s² 2s² 2p⁶ 3s² 3p¹

Cl - 1s² 2s² 2p⁶ 3s² 3p⁵

Ca - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Cr - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁴

Fe - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

Cu - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d¹⁰

Isoelectronic Species - O^2- , F^- , Ne, Na⁺

2) The Spin Quantum Number (msms) describes the angular momentum of an electron. An electron spins around an axis and has both angular momentum and orbital angular momentum. Because angular momentum is a vector, the Spin Quantum Number (s) has both a magnitude (1/2) and direction (+ or -).

Each orbital can only hold two electrons. One electron will have a +1/2 spin and the other will have a -1/2 spin. Electrons like to fill orbitals before they start to pair up. Therefore the first electron in an orbital will have a spin of +1/2. After all the orbitals are half filled, the electrons start to pair up. This second electron in the orbital will have a spin of -1/2. If there are two electrons in the same orbital, it will spin in opposite directions.

3) There are 4 lines that are visible in atomic line spectrum for H-atom which are -

i) 410.2 nm which is close to ultraviolet spectrum

ii) 434.1 nm - Violet

iii) 486.1 nm - Blue

iv) 656.3 nm - Red