Answer:
C
Explanation:
Hello,
To understand how electrons are filled in a shell or orbital, they follow certain principles which govern them and once you grasp those principles, it becomes easy for you to solve any problem relating to them. They are;
1. Aufbau's principle
2. Hund's rule
3 . Paulie's exclusion principle
The above principles helps to locate the position of an electron in a orbital.
Likewise electrons tend to acquire stability either by losing electrons or gaining electrons.
The tendency to lose electrons is know as electropositivity while the tendency to lose electrons is electronegativity.
Generally, elements having it's electron in S-orbital belongs to s-block of the periodic table(I.e group 1 or 2 element) while elements having its last electron in P- Orbital belongs to p-block of periodic table.
P block elements are from group 3 - group 8.
Electronegativity is the tendency of an element to attract and electron towards itself and it increases across the period and decreases down the group.
So p-block elements in the same period s-block elements are likely to be more electronegative than s-block elements.
In the options above
A = 5s² = group 2 element
B = 5s²5p² = group 4 element
C = 5s²5p⁵ = group 7 element
D = 5s²5p⁶ = group 8 element.
From the explanation above, you'd think the answer is option D which is group 8 but unfortunately that is incorrect because group 8 element have completely filled orbital and do not require extra electrons to attain stability hence they have little or no electronegative value. So option c is the correct amswer
