In this lesson we discuss how intermolecular forces arise due to the concept of electronegativity and bond polarity and other bond properties. This is lesson ten in our physical chemistry series for Unit 3: Chemical Bonding (from the Cambridge International AS Chemistry Curriculum (9701) 2019-2021 curriculum). LESSON OBJECTIVE: Understand the different intermolecular forces and their implications for a molecules physical properties. Explain these forces in terms of electronegativity and polarity. Learning Outcomes (from the Cambridge AS Chemistry Curriculum 2019-2021): 3.3 Intermolecular forces, electronegativity and bond properties. a) describe hydrogen bonding, using ammonia and water as simple examples of molecules containing N-H and O-H groups b) understand, in simple terms, the concept of electronegativity and apply it to explain the properties of molecules such as bond polarity, the dipole moments of molecules and the behaviour of oxides with water c) explain in terms of bond energy, bond length and bond polarity and use them to compare the reactivities of covalent bonds d) describe intermolecular forces (van der Waals’ forces) based on permanent and induced dipoles, as in, for example, CHCl3(l); Br2(l) and the liquid Group 18 element.

In this lesson we discuss the formation of sigma and pi bonds, the hybridisation of orbitals and the molecular geometries that form due to electron repulsion. This is lesson nine in our physical chemistry series for Unit 3: Chemical Bonding (from the Cambridge International AS Chemistry Curriculum (9701) 2019-2021 curriculum). LESSON OBJECTIVE: Understand how sigma and pi bonds form and investigate the concept of atomic orbital hybridisation. Identify molecular geometries and understand bond angles observed due to electron pair repulsion. Learning Outcomes: (from the Cambridge AS Chemistry Curriculum 2019-2021): 3.2 Covalent bonding and co-ordinate (dative covalent) bonding including shapes of simple molecules b) describe covalent bonding in terms of orbital overlap, giving σ and π bonds, including the concept of hybridisation to form sp, sp2 and sp3 orbitals (see also Section 14.3) c) explain the shapes of, and bond angles in, molecules by using the qualitative model of electron-pair repulsion (including lone pairs), using as simple examples BF3 (trigonal planar), CO2 (linear), CH4 (tetrahedral), NH3 (pyramidal), H2O (non-linear), SF6 (octahedral), PF5 (trigonal bipyramidal) d) predict the shapes of, and bond angles in, molecules and ions analogous to those specified in 3.2© (see also Section 14.3)

In this lesson we give an overview of the three types of chemical bonding (ionic, covalent and metallic) and an introduction into how VSEPR theory dictates molecular geometries. This is lesson eight in our physical chemistry series for Unit 3: Chemical Bonding (from the Cambridge International AS Chemistry Curriculum (9701) 2019-2021 curriculum). LESSON OBJECTIVE: Understand how ionic, covalent and metallic bonds form. Rationalise molecular geometries using VSEPR theory. Learning Outcomes (from the Cambridge AS Chemistry Curriculum 2019-2021): 3.1 Ionic bonding a) describe ionic bonding, using the examples of sodium chloride, magnesium oxide and calcium fluoride, including the use of ‘dot-and- cross’ diagrams 3.2 Covalent bonding and co-ordinate (dative covalent) bonding including shapes of simple molecules a) describe, including the use of ‘dot-and-cross’ diagrams: (i) covalent bonding, in molecules such as hydrogen, oxygen, chlorine, hydrogen chloride, carbon dioxide, methane, ethene (ii) co-ordinate (dative covalent) bonding, such as in the formation of the ammonium ion and in the Al2Cl6 molecule c) explain the shapes of, and bond angles in, molecules by using the qualitative model of electron-pair repulsion (including lone pairs), using as simple examples BF3 (trigonal planar), CO2 (linear), CH4 (tetrahedral), NH3 (pyramidal), H2O (non-linear), SF6 (octahedral), PF5 (trigonal bipyramidal) 3.4 Metallic bonding a) describe metallic bonding in terms of positive ions surrounded by delocalised electrons

In this lesson we focus on the concept of ionisation energy and how to interpret ionisation energy trends in the periodic table. This is lesson seven in our physical chemistry series for Unit 2: Atomic Structure (from the Cambridge International AS Chemistry Curriculum (9701) 2019-2021 curriculum). LESSON OBJECTIVE: Understand ionisation energy and use this to rationalise trends in the Periodic Table and to deduce electronic configurations of elements. To Interpret ionisation energy data. Learning Outcomes (from the Cambridge AS Chemistry Curriculum 2019-2021): 2.3 Electrons: energy levels, atomic orbitals, ionisation energy, electron affinity d) i) explain and use the term ionisation energy ii) explain the factors influencing the ionisation energies of elements iii) explain the trends in ionisation energies across a period and down a group of the Periodic Table e) deduce the electronic configurations of elements from successive ionisation energy data f) interpret successive ionisation energy data of an element in terms of the position of that element within the Periodic Table

In this lesson we focus on the rules stating how electrons fill orbitals and how to write electron subshell configuration. This is lesson six in our physical chemistry series for Unit 2: Atomic Structure (from the Cambridge International AS Chemistry Curriculum (9701) 2019-2021 curriculum). LESSON OBJECTIVE: Understand how electrons fill orbitals and to determine subshell electronic configuration for given atoms and ions. LEARNING OUTCOMES (from the Cambridge AS Chemistry Curriculum 2019-2021): 2.3 Electrons: energy levels, atomic orbitals, ionisation energy, electron affinity c) state the electronic configuration of atoms and ions given the proton (atomic) number and charge, using the convention 1s22s22p6, etc.

In this lesson we focus on the electron and how it arranges itself around the nucleus in principal quantum levels, subshells and atomic orbitals. This is lesson five in our physical chemistry series for Unit 2: Atomic Structure (from the Cambridge International AS Chemistry Curriculum (9701) 2019-2021 curriculum). LESSON OBJECTIVE: Understand how the electron exists in principal quantum levels and subshells, to describe the relative energies of the s, p and d orbitals and to sketch the s and p orbitals. LEARNING OUTCOMES (from the Cambridge AS Chemistry Curriculum 2019-2021): 2.3 Electrons: energy levels, atomic orbitals, ionisation energy, electron affinity a) describe the number and relative energies of the s, p and d orbitals for the principal quantum numbers 1, 2 and 3 and also the 4s and 4p orbitals b) describe and sketch the shapes of s and p orbitals

In this lesson we go over the subatomic particles in the atom and the concept of the nucleus. This is lesson four in our physical chemistry series for Unit 2: Atomic Structure (from the Cambridge International AS Chemistry Curriculum (9701) 2019-2021 curriculum). LESSON OBJECTIVE: Understand the properties of subatomic particles of an element including naming, mass and charge conventions for elements and isotopes. LEARNING OUTCOMES (from the Cambridge AS Chemistry Curriculum 2019-2021): 2.1 Particles in the atom a) identify and describe protons, neutrons and electrons in terms of their relative charges and relative masses b) deduce the behaviour of beams of protons, neutrons and electrons in electric fields c) describe the distribution of mass and charge within an atom d) deduce the numbers of protons, neutrons and electrons present in both atoms and ions given proton and nucleon numbers (atomic and mass numbers) and charge 2.2 The nucleus of the atom a) describe the contribution of protons and neutrons to atomic nuclei in terms of proton (atomic) number and nucleon (mass) number b) distinguish between isotopes on the basis of different numbers of neutrons present c) recognise and use the symbolism xyA for isotopes, where x is the nucleon (mass) number and y is the proton (atomic) number

This lesson goes over the concept of stoichiometry and how to do stoichiometric calculations that involve the reactions of masses and volumes. This is lesson three in our physical chemistry series for Unit 1: Atoms, Molecules and Stoichiometry (from the Cambridge International AS Chemistry Curriculum (9701) 2019-2021 curriculum). LESSON OBJECTIVE: To balance equations and perform calculations using the mole concept and stoichiometric relationships. Understand the concept of a titration. LEARNING OUTCOMES (from the Cambridge AS Chemistry Curriculum 2019-2021): 1.5 Reacting masses and volumes (of solutions and gases) a) write and construct balanced equations b) perform calculations, including use of the mole concept, involving: i) reacting masses (from formulae and equations) ii) volumes of gases (e.g. in the burning of hydrocarbons) III) volumes and concentrations of solutions c) deduce stoichiometric relationships from calculations

This lesson goes over the concepts of empirical and molecular formulas and how to correctly use significant figures. This is lesson two in our physical chemistry series from unit 1: Atoms, Molecules and Stoichiometry (from the Cambridge International AS Chemistry Curriculum). LESSON OBJECTIVE: Understand and calculate empirical and molecular formulas. Understand how to report calculations to the correct amount of significant figures. LEARNING OUTCOMES (taken from the Cambridge International AS and A Level Chemistry (9701) 2019-2021 curriculum): 1.4 The calculation of empirical and molecular formulae a) define and use the terms empirical and molecular formula b) calculate empirical and molecular formulae, using combustion data or composition by mass

This lesson goes over the concepts of relative mass, the mole and Avogadro’s constant. This is lesson one in our physical chemistry series from unit 1: Atoms, Molecules and Stoichiometry (from the Cambridge International AS Chemistry Curriculum). LESSON OBJECTIVE: To understand and calculate masses of atoms and molecules based on the 12C scale, to investigate the concept of the mole and to be able to analyse mass spectra. LEARNING OUTCOMES (taken from the Cambridge International AS and A Level Chemistry (9701) 2019-2021 curriculum): 1.1 Relative masses of atoms and molecules a) define and use the terms relative atomic, isotopic, molecular and formula masses, based on the 12C scale 1.2 The mole and the Avogadro constant a) Define and use the term mole in terms of the Avogadro constant 1.3 The determination of relative atomic masses, Ar a) Analyse mass spectra in terms of isotopic abundances b) Calculate the relative atomic mass of an element given the relative abundances of its isotopes, or its mass spectrum.