AQA AS Physical Chemistry - Electronic Structure PDF

AS CHEMISTRY 3.1.1 ATOMIC STRUCTURE ELECTRON CONFIGURATION Electrons are organised into ENERGY LEVELS (Shells). Within these energy levels they exist in ORBITALS. Each orbital can hold a maximum of 2 electrons (an elect...

AS CHEMISTRY 3.1.1 ATOMIC STRUCTURE ELECTRON CONFIGURATION Electrons are organised into ENERGY LEVELS (Shells). Within these energy levels they exist in ORBITALS. Each orbital can hold a maximum of 2 electrons (an electron pair) which have opposite spins. “s” orbital “p” orbital Exist in sets of three Spherical in shape Figure of 8 in shape (x, y, z) ELECTRONIC STRUCTURE You must be able to write the electronic structures of atoms and ions up to and including Kr. 36Kr 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 LEARN THIS SEQUENCE! LARGE NUMBERS = ENERGY LEVEL LETTERS = ORBITAL TYPE SMALL NUMBERS = NUMBER OF ELECTRONS IN THOSE ORBITALS ELECTRONS IN BOXES These show the pairings of the electrons in each orbital. The arrows represent the fact that pairs of electrons have opposite spins. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 ↼↼ ↼ ↼ ↼↼ ↼ ↼ ↼↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼ ↼↼ Important! Hund’s Rule: When filling “p” and “d” orbital groups, the electrons occupy the orbitals individually first, then pair up! AQA www.chemistrycoach.co.uk © scidekick ltd 2024 AS CHEMISTRY 3.1.1 ATOMIC STRUCTURE HINTS | TIPS | HACKS The higher the energy level, the greater the amount of energy the electrons in them possess. Electrons fill orbitals from the lowest energy level to the highest. The orbital that houses the LAST electron tells us the “block” of the periodic table that the element is in. The total number of electrons in the highest energy level tells us which group the element is in. The 4s orbital is always filled before the 3d orbital. Exceptions: Chromium (Cr) is 1s2 2s2 2p6 3s2 3p6 4s1 3d5 and NOT 1s2 2s2 2p6 3s2 3p6 4s2 3d4 Copper (Cu) is 1s2 2s2 2p6 3s2 3p6 4s1 3d10 and NOT 1s2 2s2 2p6 3s2 3p6 4s2 3d9 You do not need to explain why, just remember them! How To Write Electronic Structures for Atoms & Ions AQA www.chemistrycoach.co.uk © scidekick ltd 2024