Question

An ion M3+ has 2 electrons in k shell and 8 electrons in L shell.
a) Identify the element M.
b) Write its atomic number and valency.
c) Write the formula of the compound formed by M with
chlorine.
d) Which has stable electronic configuration M or M3+?
Justify.​

Answer 1

Answer:

K                          L                              M

2                          8                               8

Thus, atomic number of the element will be 18.

And electronic configuration of the element can be given as:

1s² 2s² 2p⁶ 3s² 3p⁶

Thus, total number of s electron is 6.

Answer 2

If an ion M3+ has 2 electrons in K shell and 8 electrons in the L shell, then

a) The element M is Aluminum (Al) because the distribution of electrons in its K, L, and M shell will be 2, 8, 3.

b) The atomic number of Aluminum is 13. Since it has 3 electrons in its valence shell, it will donate these electrons to form M³⁺ and hence its valency is 3.

c) M reacts with Chlorine to form MCl₃.

d) Stable electronic configuration is present in M³⁺ because the octet rule says that an atom is stable when its outermost shell has electrons. So, it will donate 3 electrons to attain a stable electronic configuration.