Question

Which of the following not a metal?
(a) Copper
(b) Sulphur
(c) Aluminium
(d) Iron

Answer 1

Metals are located on the left side of the periodic table, and non-metals are positioned on the right side. One can precisely identify a metal or non-metal by obtaining its electronic configuration.

Complete step by step answer:
(1) All elements whether metals, non-metals or metalloids are placed in the periodic table according to their atomic number which is the number of protons in the atom. Metals are placed on the left side of the periodic table with a particular colour of the section in which they are placed. Similarly, non-metals, and metalloids have different colours which help us to differentiate, and locate them.
(2) More precise way is to see the number of valence electrons in the outermost shell of the elements. If the number of electrons in the outermost shell is in between 1-4 then it will be a metal, and if the number of electrons in the outermost shell is in between 5-7 then it will be a non-metal.
(3) Number of electrons in the outermost shell can be calculated by the electronic configuration.

For option (a) Copper, its atomic number is 29, so, its electronic configuration is ${\left[ {{\text{Ar}}} \right]_{18}}4{s^1}3{d^{10}}$. So, its outermost shell is ${\text{4s}}$, and it has 1 electron. Hence, it is a metal.

For option (b) Sulphur, its atomic number is 16, so, its electronic configuration is ${\left[ {{\text{Ne}}} \right]_{10}}3{s^2}3{p^4}$. So, its outermost shell is ${\text{3s and 3p}}$, and it has 6 electrons. Hence, it is non-metal.

For option (c) Aluminium, its atomic number is 13, so, its electronic configuration is ${\left[ {{\text{Ne}}} \right]_{10}}3{s^2}3{p^1}$. So, its outermost shell is ${\text{3s and 3p}}$, and it has 3 electrons. Hence, it is a metal.

For option (a) Iron, its atomic number is 26, so, its electronic configuration is ${\left[ {{\text{Ar}}} \right]_{18}}4{s^2}3{d^6}$. So, its outermost shell is ${\text{4s}}$, and it has 2 electrons. Hence, it is a metal.

Hence, option (b) Sulphur is the correct answer.

Note:
Hydrogen is placed on the left-hand side of the periodic table along with the metals, but its position is anomalous because it shows the electropositivity property like metals, and it can also gain 1 electron to gain stability like non-metals.