select the correct answer. what is the electron configuration of an element with atomic number 20?\na…

select the correct answer. what is the electron configuration of an element with atomic number 20?\na. (1s^{2}2s^{2}2p^{6}3s^{2}3p^{5})\nb. (1s^{2}2s^{2}2p^{6}3s^{2}3p^{6})\nc. (1s^{2}2s^{2}2p^{6}3s^{2})\nd. (1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2})\ne. (1s^{2}2s^{2}2p^{6})

select the correct answer. what is the electron configuration of an element with atomic number 20?\na. (1s^{2}2s^{2}2p^{6}3s^{2}3p^{5})\nb. (1s^{2}2s^{2}2p^{6}3s^{2}3p^{6})\nc. (1s^{2}2s^{2}2p^{6}3s^{2})\nd. (1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2})\ne. (1s^{2}2s^{2}2p^{6})

Answer

Explanation:

Step1: Recall electron - filling rules

Electrons fill orbitals in the order 1s, 2s, 2p, 3s, 3p, 4s, 3d, etc. The s - orbital can hold a maximum of 2 electrons, the p - orbital can hold a maximum of 6 electrons.

Step2: Calculate number of electrons

An element with atomic number 20 has 20 electrons.

Step3: Fill the orbitals

1s orbital is filled first with 2 electrons (1s²). Then 2s is filled with 2 electrons (2s²), 2p is filled with 6 electrons (2p⁶), 3s is filled with 2 electrons (3s²), 3p is filled with 6 electrons (3p⁶), and then 4s is filled with the remaining 2 electrons (4s²). So the electron - configuration is 1s²2s²2p⁶3s²3p⁶4s².

Answer:

D. 1s²2s²2p⁶3s²3p⁶4s²