- The Hund Rule – orbital with the same energy level (degenerate orbitals), electron will occupy different orbital singly/one electron first with the parallel spin, before pairing.(Reject: same spin, spin with same direction) STPM 2008, 2007
- Pauli Exclusive Principle – Each orbital can hold a maximum of two electrons withopposite spin. (Reject: different spin) STPM 2007
- Aufbau principle – Electrons occupy orbitals with the lowest energy level first. (Reject: occupy lower energy first) STPM 2006, 2007
- Vapour pressure – the pressure exerted by a vapour that is in equilibrium with its liquidat a fixed temperature in a closed system. It is due to the collision of the vapour particles on the walls of the container. STPM 2004
STOICHIOMETRY
- Molarity (M) [concentration of a fluid solution] – defined as the moles of a solute per volume of solution.
- Density [concentration of a fluid solution] – defined as the mass of solution per volume of solution.
- Dilution – addition of solvent to a solution resulting in an increase in the volume of the solution and a decrease in the concentration of the solute in solution.
- Precipitation reaction (also refer to as double-displacement reaction) – a reaction that involve two aqueous salts being added together to form ions and a solid salt precipitate.
ACID-BASE EQUILIBRIA
- Arrhenius acid – acid yields H3O+ when added to water
- Arrhenius base – base yields OH- when added to water
- Bronsted-Lowry acid (proton donor) – a substance that donate a proton, H+ to a base.
- Bronsted-Lowry base (proton acceptor) – a substance that accept a proton, H+ from an acid.
- Conjugate acid – a species (molecule or ion) formed when a proton is added to a base.
- Conjugate base – a species (molecule or ion) formed when a proton is removed from an acid.
- Lewis acid – an electron-pair acceptor.
- Lewis base – an electron-pair donor.
- Electrolyte (also electrolytic conductor) – a chemical compound that will conduct electricity in the molten state or in aqueous solution.
- Strong acid – an acid that is almost completely dissociated in aqueous solution. (Stronger the acid, the weaker its conjugate base)
- Weak acid – an acid that is only partially dissociated in aqueous solution. (Weaker the acid, the stronger its conjugate base)
