What is the valency of an element with the elec... - JAMB Chemistry 2023 Question
What is the valency of an element with the electronic configuration 2, 8, 7?
A
7
B
1
C
2
D
3
correct option: b
The valency of an element is determined by the number of electrons it needs to gain or lose to achieve a stable, noble gas electron configuration.
For the element with the electronic configuration 2, 8, 7:
- The first two electrons fill the first energy level (1s²).
- The next eight electrons fill the second energy level (2s² 2p⁶).
- The remaining seven electrons are in the third energy level (3s² 3p⁶ 3d¹).
The element is in Group 17 (Group VIIA) of the periodic table, which includes the halogens. Elements in this group typically have a valency of 1 by gaining one electron to achieve a stable configuration.
Therefore, the correct answer is 1
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