Question

use the periodic table and your knowledge of atomic structure to match each element with the correct electron - configuration. chromium (cr) arsenic (as) chlorine (cl) phosphorus (p) sodium (na)

Explanation:

Step1: Recall electron - configuration rules

Electron configurations are written based on the Aufbau principle, Pauli - exclusion principle, and Hund's rule. We know the atomic numbers of the elements and fill the orbitals accordingly.

Step2: Identify atomic numbers

Chromium (Cr) has an atomic number of 24. Its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{5}$ due to the stability of half - filled sub - shells.
Arsenic (As) has an atomic number of 33. Its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{3}$.
Chlorine (Cl) has an atomic number of 17. Its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}$.
Phosphorus (P) has an atomic number of 15. Its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$.
Sodium (Na) has an atomic number of 11. Its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{1}$.

Step3: Match the configurations

• Chromium (Cr): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{5}$
• Arsenic (As): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{3}$
• Chlorine (Cl): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}$
• Phosphorus (P): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$
• Sodium (Na): $1s^{2}2s^{2}2p^{6}3s^{1}$

Answer:

Chromium (Cr): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{5}$
Arsenic (As): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{3}$
Chlorine (Cl): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}$
Phosphorus (P): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$
Sodium (Na): $1s^{2}2s^{2}2p^{6}3s^{1}$