1a. Atoms, Elements, Compounds and Mixtures
14 lessons · The building blocks of matter and how we separate them.
01Atoms
Start here if you want to understand what atoms actually are. This video builds the nuclear model from first principles — protons, neutrons, and electrons — and explains how their properties (mass, charge, and location) determine everything about how atoms behave. You'll also get a genuine sense of how astonishingly small and mostly empty an atom really is.
02Elements
03Isotopes
Chlorine's relative mass of 35.5 is the perfect puzzle to open this topic — it can't be a single whole-number mass, so what's going on? This video answers that question by introducing isotopes: atoms of the same element with different numbers of neutrons. You'll learn how to write isotope notation, calculate relative atomic mass as a weighted average, and see why radioactive isotopes like carbon-14 have real-world applications from carbon dating to medical imaging.
04Compounds
Chemical formulae are the universal language of chemistry — and once you can read them, a whole new level of understanding opens up. This video teaches you a step-by-step method for decoding any formula: counting elements, reading subscripts, and working through brackets, finishing with the Co versus CO example that shows why capitalisation can mean the difference between cobalt and carbon monoxide. The foundation you need before tackling formula masses and balanced equations.
05Balancing Chemical Equations
If balancing equations feels like guesswork, this video gives you a method that turns it into a systematic process. You'll start with the Law of Conservation of Mass, understand why equations must balance, and then work through a series of examples from simple single-step reactions to combustion equations — building confidence and speed as you go.
06Conservation of Mass
This video starts with Lavoisier's 18th-century experiments and uses them to show why the Law of Conservation of Mass isn't just a rule to memorise — it's a consequence of the fact that atoms are never created or destroyed in a chemical reaction. You'll see why reactions that appear to gain or lose mass are really just losing gases to or gaining them from the surroundings, and you'll work through the calculation method that lets you find a missing mass from a balanced equation.
07Relative Atomic Mass and Formula Mass
If you're struggling to calculate the mass of chemical compounds, this video gives you a clear, step-by-step method. You'll learn what relative atomic mass and relative formula mass actually mean, where to find the values you need, and how to apply them to both simple molecules and ionic compounds with brackets. By the end you'll be able to calculate Mr for any compound — the essential first step in almost every quantitative chemistry calculation.
08Separation Techniques (overview)
After a reaction, chemists rarely end up with just the compound they wanted — there's almost always something else in the mix. This video surveys all the main separation techniques you need to know for GCSE: filtration, evaporation, crystallisation, distillation, fractional distillation, and chromatography. It explains the principle behind each one and connects them to real-world examples so you know when to choose which technique.
09Filtration
This video covers everything you need to know about filtration for GCSE — from the underlying principle to the practical setup and the vocabulary that examiners expect. You'll see why filter paper works, what residue and filtrate mean, and how pore size determines what can and cannot be separated, finishing with a look at the limitations that make other techniques necessary for dissolved substances.
10Evaporation
This video explains how evaporation and crystallisation work together to recover a dissolved solid from a solution, and why evaporation happens at the surface of a liquid even below its boiling point. You'll see the practical setup, understand the particle-level explanation, and learn when to stop heating to produce crystals rather than a dry powder.
11Distillation
This video takes you through two essential separation techniques — simple distillation and fractional distillation — using clear practical demonstrations and real exam-style questions. You'll learn the equipment needed, the role each component plays, and the key hazards and safety precautions the examiner expects you to know.
12Paper Chromatography
This video unpacks paper chromatography from start to finish — the underlying principle, the required practical technique, and how to calculate and use Rf values to identify substances. By the end you'll understand not just how to carry out the experiment, but why each step matters and how to interpret a chromatogram as evidence.
13The History of the Atom
14Electronic Structure
In under 15 minutes, this video takes you from knowing what an electron is to writing the full electron configuration of any element in the first three periods of the periodic table. You'll see how the 2,8,8 rule connects to the structure of the periodic table, why elements in the same group have similar chemistry, and why the Bohr model is still the starting point for understanding bonding despite its known limitations.
1b. The Periodic Table
7 lessons · Trends, groups and the story of how the table was developed.
01Development of the Periodic Table
02The Modern Periodic Table
03Metals and Non-metals
04Group 1: The Alkali Metals
05Group 7: The Halogens
06Group 0: The Noble Gases
07