Question

An element X belongs to the 3 rd period and group 16 of the Modern Periodic table. Name the element X and state whether it is metallic or non-metallic.

Answer 1

Element belongs to 3rd period and group 16. So, we have to find out how many shells it has from the group number and the number of valence electrons from the period number. Number of electrons each electron shell can hold is given by $2{n^2}$ where n is the number of the electronic shell and is denoted by integers 1,2,3…. etc.

Complete step by step solution: A period in the Modern Periodic Table is a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton in its atomic nucleus. Each element is less metallic than its predecessor as electrons are closer to the nucleus due to the crowding of electrons in the same electronic shell. The nucleus of the atom is positively charged and the electrons possess negative charge and hence they attract each other. So going across a period, energy required to remove an electron required is more and hence metallic character decreases. There are a total 7 periods in the Modern Periodic Table.
A group in the Modern Periodic Table is a column of chemical elements. All elements in a group have the same number of valence electrons i.e. same number of electrons in the last/valence shell. Each element in a group has one more electronic shell than its predecessor. Metallic character increases down each group of the Table as the outer electrons are further from the nucleus and require less energy for their removal. There are a total of 18 groups in the Modern Periodic Table.
So, since the element is in the 3rd period it has 3 electron shells. If an element is not a transition metal, then valence electrons increase in number as we count groups left to right, along a period. Each new period begins with one valence electron. Groups 3 through 12 are excluded as these are transitional metals, which have special circumstances. Following this rule, it is present in group number 16 so the number of valence electrons is 6. We know the number of electrons each electron shell can hold is given by $2{n^2}$ where n is the number of the electronic shell. Thus for n=1 number of electrons is 2 and for n=2 the number of electrons is 8. Hence the electronic configuration of the element X is 2,8,6 and its atomic number is 16.
In the Modern Periodic Table, the element Sulphur has atomic number 16.

So, the solution is that the element X is Sulphur and it is non metallic.

Note: Elements in groups 1 and 2 are collectively known as s-block elements as their valence shell is the s shell. Groups 3-12 constitute the d-block elements while groups 13-18 constitute the p-block elements. The f-block elements constitute a different group in the footnote of the table. So Sulphur is a p-block element.