JAMB - Chemistry (2023 - No. 55)
What is the valency of an element with the electronic configuration 2, 8, 7?
7
1
2
3
설명
The valency of an element is determined by the number of electrons it gains or loses to achieve a stable electron configuration. For an element with the electronic configuration 2, 8, 7, the outermost shell (valence shell) has 7 electrons. To achieve stability, it needs 1 more electron to fill the outermost shell, so its valency is 1.