Invisible radiation which has a longer wavelength than the red colour of the visible spectrum, and which is commonly associated to heat.

Notable features or qualities of a person transmitted through  the genes from parent to offspring.

An attraction or repulsion between molecules. Intermolecular forces are much weaker than chemical bonds.

Weak forces (either attraction or repulsion) between molecules. The attractive forces are collectively called "van der Waals forces". Intermolecular forces may be feeble (in fact much weaker than intra-molecular forces, i.e. chemical bonds within an individual molecule), but without them life as we know it would be impossible. Water, for example, could not condense from vapour into solid or liquid forms.

An atom or group of atoms that has either lost one or more electrons, making it positively charged (a cation), or gained one or more electrons, making it negatively charged (an anion).

An atom or group of atoms that has either lost one or more electrons, making it positively charged (a cation), or gained one or more electrons, making it negatively charged (an anion).

An atom or group of atoms that has either lost one or more electrons, making it positively charged (a cation), or gained one or more electrons, making it negatively charged (an anion).

The physical process by which an atom or a molecule converts to an ion (it possess electric charge) by gaining or loosing electron(s).

The energy required for the ionization process to take place. The ionization energy is greater in small atoms because their electrons are strongly attracted to the nucleus. On the contrary, removing electrons from bigger atoms requires less ionization energy.

Add or remove electrons from an element so that it becomes an ion.

Chemical compounds with the same number of atoms but different physical and chemical properties due to the different arrangement of their atoms (same molecular but different structural formulas). Isomers are named after the Greek words “isos” meaning equal and “meros” meaning part.

The process by which one molecule is transformed into another molecule (isomers), which has exactly the same atoms but in different arrangement.