Concise Chemistry Class 9 ICSE Solutions for Chapter 1 - Language of Chemistry

Chemistry has also had its language and that includes symbol, valency, equation, ion, atom, molecule, reaction, and so on. A chemical symbol is always denoted in the short form related to a particular or specific element or an atom of that element. With the help of these chemical symbols, it makes it easier for us to write chemical formulas and equations instead of writing the lengthy chemical names of each element or atom. Several scientists have given a thought and plan related to the symbolic representation of these elements.

What is a Valency?

Valency is defined as the combining capacity of an element or in other words it is related to the number of electrons which an atom gains or shares or loses when this chemical reaction takes place along with other elements is known as Valency. The classification of these elements is based on the monovalent, divalent, and so on is related to their valency. Molecules are basically formed in order to satisfy the valency of an atom.

What is a Chemical Symbol?

A chemical symbol is represented with the help of two letters which refer to the atom of a chemical element. A symbol plays an indispensable role in the study of the elements. Example Chlorine is written as Cl and the name of the element is chlorine, one atom of chlorine and the atomic mass of chlorine is 17 a.m.u

Valency represents the combining capacity of an atom or radical in its own way. It is generally considered as the number of hydrogen atoms that will get combined with or displace one atom of that element or radical. The nature of metal is electropositive and loses electrons in order to attain octet configuration. Metals belonging to Group 1 are all alkali metals and have got only one valence electron and are univalent whereas metals belonging to Group 2 are all alkaline metals with 2 valence electrons and are all divalent in nature. Metals that are in Group 3 consist of 3 valences and are all trivalent in nature.

• Na – e–  ⇨ Na⁺ (univalent).

• Ca – 2e–  ⇨ Ca₂⁺ (divalent).

• Al – 3 e–  ⇨ Al₃⁺ (trivalent).

The nature of non-metal is supposed to be electronegative in nature and gain electrons to attain octet configuration.

• Cl + e– ⇨ Cl^– (univalent).

• O + 2e– ⇨ O₂^- (divalent).

• N + 3e– ⇨N₃^- (trivalent).

Metals belonging to Group 4 like carbon, silicon, and other metals have 4 valence electrons and are tetravalent in nature. In normal cases or conditions, these elements share electrons with one or more other elements in order to gain octet configuration.

However, Sn₄⁺ and Pb₄⁺ also exist.

Variable Valency

When there is a loss of electrons from the valence shell and also from the penultimate shell, then it is known as Variable Valency.

Radicals

When a single atom or a group of atoms starts behaving like a single unit and if it consists of negative and positive ions then it is known as Radical. Radical is said to be very reactive as well as with a unique valency.

Table of Positive Valency

Table of Negative Valency