Elements and Symbols

An element is a pure substance that cannot be broken down into simpler substances by ordinary chemical processes. There are over 100 known elements.

Symbols of Elements

Element symbols are derived in three main ways:

1. From the First Letter of the Element's Name

2. From the First Letter and Another Letter of the Name

3. From the Latin Name of the Element

Classification of Elements

Elements can be grouped as:

• Metals – e.g., iron, zinc, tin, aluminium, copper
• Non-metals – e.g., chlorine, oxygen, sulphur, fluorine, hydrogen
• Metalloids – elements with both metallic and non-metallic properties, e.g., silicon, germanium

Differences Between Metals and Non-Metals

Valency

Valency is the combining capacity of an element. It is the number of hydrogen atoms that can combine with or be replaced by one atom of the element. Valency is often linked to the number of electrons in the outermost shell (valence electrons).

Valency can be:

• Positive – when electrons are lost
• Negative – when electrons are gained

Metals usually have positive valencies, while non-metals typically have negative valencies. Some elements can exhibit multiple valencies, also known as oxidation states.

Examples of Element Valencies

Radicals

A radical is a group of atoms that behaves as a single unit and carries a positive or negative charge. Acid radicals are negatively charged radicals that react as a single entity.

Examples of Radicals and Their Valencies