Define 'molecule'Define 'ions'Define cation and an anionDefine 'chemical formula' Define 'valency'Explain the Law of Conservation of Mass

Molecule: A molecule is the smallest particle in a chemical element or compound that has the chemical properties of that element or compound. Molecules are made up of atoms that are held together by chemical bonds. These bonds form as a result of the sharing or exchange of electrons among atoms.

Ions: Ions are atoms or molecules that have gained or lost one or more of their valence electrons, giving them a positive or negative charge.

Cation and Anion: A cation is a positively charged ion, with fewer electrons than protons, while an anion is negatively charged, with more electrons than protons. Because of their opposite electric charges, cations and anions attract each other and readily form ionic compounds.

Chemical Formula: A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, and plus (+) and minus (−) signs.

Valency: In chemistry, the valency or valence of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules. The concept of valency evolved to quantify the number of bonds formed by an atom in a molecule.

Law of Conservation of Mass: The Law of Conservation of Mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.