[H2 CHEM] Chapter 1 - Atomic Structure

Chapter 1 ELAINE PEH (COPYRIGHTED) © Atomic Structure

CHAPTER ANALYSIS FOCUS EXAM WEIGHTAGE ELAINE PEH (COPYRIGHTED) ©

Properties of The Three Sub-Atomic Particles Quantum Mechanical Model of the Atom Writing Electronic Configurations IonisationEnergy KEY CONCEPT ELAINE PEH (COPYRIGHTED) ©

ATOM • The smallest particle of an element. • Made up of sub-atomic particles – proton, neutron, electron. • 𝑍 𝐴𝑋 X = symbol of the element A = atomic mass (nucleon number) = total number of protons and neutrons Z = atomic number (proton number) ELAINE PEH (COPYRIGHTED) © Properties of The Three Sub-Atomic Particles

BEHAVIOUR IN AN ELECTRIC FIELD • The angle of deflection of particles depends on their mass and charges. k = proportionality constant ELAINE PEH (COPYRIGHTED) © Properties of The Three Sub-Atomic Particles

ELAINE PEH (COPYRIGHTED) © Quantum Mechanical Model of the Atom Protons and neutrons are found in the nucleus of an atom whereas electrons are found in spaces outside the nucleus. These spaces can be categorised as (1) principal quantum shells (2) subshells (3) orbitals Based on where they are found, each electron within the same atom have different energy level.

ELAINE PEH (COPYRIGHTED) © Each principal quantum number indicates the principal quantum shell. Each principal quantum shell (n = 1, 2, 3, or 4) contains either 1 (s), 2 (s, p), 3 (s, p, d), or 4 (s, p, d, f) subshells. The s- subshell has 1 orbital, p-subshell has 3 orbitals, d-subshell has 5 orbitals. Each orbital holds a maximum of 2 electrons with opposite spins. Quantum Mechanical Model of the Atom Principal Quantum Shell Number of Subshell Name of Subshell Number of Orbital Maximum number of electrons (2n2) n = 1 1 1s 1 2 n = 2 2 2s, 2p 1+3 8 n = 3 3 3s, 3p, 3d 1+3+5 18 n = 4 4 4s, 4p, 4d, 4f 1+3+5+7 32

ELAINE PEH (COPYRIGHTED) © Energy LevelElectron Located

ELAINE PEH (COPYRIGHTED) © Quantum Mechanical Model of the Atom s-SUBSHELL • Spherical in shape and non-directional • As n increase, the distance of the electrons within the s-subshell also increases; electrons in 1s nearest to the nucleus. • As n increase, the size of the s-subshell increases; size of 1s < size of 2s < size of 1s < size of 3s

ELAINE PEH (COPYRIGHTED) © d-SUBSHELL • Dumbbell in shape, consisting of 5 types of orbitals • dxy, dyz, dxz, dz 2, dx 2 – dy 2 p-SUBSHELL • Dumbbell in shape, consisting of 3 types of orbitals (px, py, pz) • As n increase, the size of the p-subshell increases; size of 2p < size of 3p