Metallic and Non-metallic Properties

Metallic and Non-metallic Properties

Elements, having a tendency to lose one or more electrons and form positive ions are called metals. These are present on the left side as well as in the centre of the periodic table. Because of the formation of positive ions, these arc also called electropositive elements.

Non-metals are the elements which have a tendency to gain one or more electrons to form negative ions. Thus, these are electronegative elements.

There are some elements also which exhibit the properties of both metals and non-metals. These are called metalloids. In the modern periodic table, a zig-zag line separates metals from non-metals. The borderline elements — boron, Silicon, germanium, arsenic, antimony, tellurium and polonium are intermediate in properties so they are called metalloids or semi-metals.

Variation Along a Period and a Group

As the effective nuclear charge acting on the valence shell electrons increases across a period, the tendency to lose electrons will decrease. Down, the group, the effective nuclear charge experienced by valence electrons decreases because the outermost electrons are farther away from the nucleus.

Hence, metallic character decreases across a period and increases down a group Non-metallic character. However increases across a period and decreases down a group.

Nature of Oxides

Oxides of the metals are of basic nature while those of non-metals are acidic. This means that along a period, the basic character of the oxides of the elements decreases while their acidic character increases.

On going down in a group of the periodic table, the order is reverse i.e., basic durum of oxides increases and acidic character of oxides decreases.

Electro Negativity

It may be defined as the relative electron attracting tendency of an atom for a shared electron pair in a covalent bond with other atom.

Variation Along a Period and a Group

The electro negativity of the elements increases along a period since the non-metallic character increases. Similarly, it decreases down the group since the non-metallic character decreases.