Elements, Atoms and Compounds

Things to remember

• The substances which are composed of its unit particles of a similar kind is known as pure substances.
• An element is the simplest form of a pure substance, which cannot be split up into two or simpler substances by any chemical reaction.
• A symbol is defined as the abbreviation of the full name of an element
• A matter is anything that occupies space and has mass.
• Compound is a substance of atoms of two or more elements formed by the chemical combination in a definite proportion by weight
• The smallest particle of an element or compound, which is capable of independent existence is called molecule.
• The smallest particle of an element, which takes part in chemical change is called atom.
• The number of protons or the number of electrons in an electrically neutral atom of an element is called atomic number