Question

electron configuration practice chemistry
name:
due date:
h. determine which of the following electron configurations are not valid: state rule has been violated.

1. (1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}4d^{10}4p^{5})
2. (1s^{2}2s^{2}2p^{6}3s^{3}3d^{5})
3. (ra7s^{2}5f^{8})
4. (kr5s^{2}4d^{10}5p^{5})
5. (xe)

Explanation:

Step1: Recall electron - shell capacity rules

Each s - subshell can hold a maximum of 2 electrons, p - subshell 6, d - subshell 10, and f - subshell 14.

Step2: Analyze 16

This electron configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}4d^{10}4p^{5}$ is valid as it follows the Aufbau principle, Pauli - exclusion principle and Hund's rule.

Step3: Analyze 17

The 3s subshell can hold a maximum of 2 electrons. Here, it has 3 electrons ($3s^{3}$), violating the Pauli - exclusion principle which states that no two electrons in an atom can have the same set of four quantum numbers and each orbital can hold a maximum of 2 electrons.

Step4: Analyze 18

The electron configuration $[Ra]7s^{2}5f^{8}$ is valid as it follows the rules for filling electron shells.

Step5: Analyze 19

The electron configuration $[Kr]5s^{2}4d^{10}5p^{5}$ is valid as it follows the Aufbau principle, Pauli - exclusion principle and Hund's rule.

Step6: Analyze 20

The noble - gas core $[Xe]$ is a valid representation for an atom that has the electron configuration of xenon as its inner - shell electrons.

Answer:

1. Violation of Pauli - exclusion principle (3s subshell has 3 electrons instead of 2).
2. Valid
3. Valid
4. Valid
5. Valid