Periodicity | Metals, Non-Metals and Metalloids#

In addition to dividing elements into s, p, d and f blocks, elements can also be divided into three categories: metals, non-metals and metalloids.

Differences between Metals and Non-Metals#

S.No.	Metals	Non-metals
1.	Metals generally lie on left side of periodic table.	Non-metals generally lie on right side of periodic table.
2.	Generally, solid at room temperature except mercury which is liquid.	Generally, solid or gas at room temperature.
3.	Good conductors of heat and electricity.	Bad conductors of heat and electricity.
4.	They have high melting and boiling points except gallium and caesium which have low melting point.	They have low melting and boiling points with the exceptions of boron and carbon.
5.	They are malleable (can be flattened into thin sheets by hammering) and ductile (can be drawn into wires).	They are brittle and are neither malleable nor ductile.
6.	Metallic character increases down the group and decreases across the period.	Non-metallic character decreases down the group and increases across the period.
7.	Examples: Na, Al, Ca, K	Examples: S, O, C, N, He

Metalloids

The transition from metals to non-metals on moving from left to right across the periodic table is not abrupt. There are some elements whose characteristics lie between metals and non-metals and are called semi-metals or metalloids. The examples of metalloids are silicon, germanium, arsenic, antimony and tellurium.

Image Credit: https://en.wikipedia.org/wiki/Periodic_table

Question#

Considering the atomic number and position in the periodic table, arrange the following elements in the increasing order of metallic character : Si, Be, Mg, Na, P.

We know that metallic character increases down the group and decreases across the period.

So, the order of increasing metallic character is P < Si < Be < Mg < Na.