Question

fix any errors in these proposed electron configurations.
number of
electrons in
atom proposed electron configuration
11 $1s^{2}2s^{2}2p^{7}$
23 $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{5}$
18 $1s^{4}2s^{4}2p^{6}3s^{4}$

Explanation:

For 11 electrons:

Step1: Recall p - orbital capacity

p - orbitals can hold a maximum of 6 electrons. In the proposed configuration \(1s^{2}2s^{2}2p^{7}\), the \(2p\) orbital has 7 electrons which is incorrect. Also, after filling \(2p\), we should fill \(3s\) for 11 electrons.

Step2: Calculate correct configuration

The correct filling order is \(1s\) (2 electrons), \(2s\) (2 electrons), \(2p\) (6 electrons, total so far \(2 + 2+6 = 10\)), then the 11th electron goes to \(3s\). So the correct configuration is \(1s^{2}2s^{2}2p^{6}3s^{1}\).

For 23 electrons:

Step1: Recall filling order

The filling order is \(1s\), \(2s\), \(2p\), \(3s\), \(3p\), \(4s\), \(3d\) etc. After \(3p\) (which holds 6 electrons), we fill \(4s\) before \(3d\).

Step2: Calculate correct configuration

Filling \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\) (total 18 electrons), then \(4s^{2}\) (total 20), then \(3d^{3}\) (since \(20 + 3=23\)). So correct configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{3}\).

For 18 electrons:

Step1: Recall s - orbital capacity

s - orbitals can hold a maximum of 2 electrons. In the proposed configuration \(1s^{4}2s^{4}3s^{4}\), each s - orbital has 4 electrons which is incorrect.

Step2: Calculate correct configuration

Fill \(1s^{2}\) (2), \(2s^{2}\) (2), \(2p^{6}\) (6), \(3s^{2}\) (2), \(3p^{6}\) (6). Total \(2 + 2+6 + 2+6=18\). So correct configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\).

Answer:

s:

• For 11 electrons: \(1s^{2}2s^{2}2p^{6}3s^{1}\)
• For 23 electrons: \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{3}\)
• For 18 electrons: \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\)