Elements, mixtures and compounds teaching resources

Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about elements and compounds (GCSE and Key Stage 3)
Elements, mixtures and compounds teacher brief

Overview: an understanding of elements, mixtures and compounds sits at the very heart of what chemistry is. Failure to grasp the differences between these superficially similar types of substance will hamper student progress. An element e.g. gold (Au) is a pure substance made from only one type of atom. A compounds e.g. water (H2O) is a pure substance made from two or more elements chemically bonded together – you can see how using formulae helps not hinders here. Elements, unlike compounds, cannot be broken down into any simple substance. Compounds however can be broken down. For example, hydrogen peroxide (H2O2) will spontaneously decompose into water and oxygen. Pass an electric current through molten lead bromide and you will get lead and bromine. Mixtures e.g. salt and water or iron and water or iron and sulfur are made from two or more different compounds, compounds and elements, or elements that are not chemically bonded and so can be separated using physical processes e.g. filtration.  

Key concept: a pure substance is either an element or a compound. An element is made from only one type of atom whereas a compound is made from different types of element chemically bonded together. Compounds can be broken down into simpler substances.

From big idea: All matter in the Universe is made of very small particles

Linked knowledge: particles, chemical bonding, separating techniques, periodic table, electrolysis, chemical formulae

Misconception [scientific idea]: an element is a substance made from one atom [made from one type of atom]; bottled water is pure [bottled water will contain dissolved ions and gases so is not pure, it is a mixture of compounds and elements]; chemical changes are the same as physical changes [chemical changes make a new substance whereas physical changes simply change the state]; atoms possess the same properties as the substance e.g. an atom of copper is shiny and hard [properties of the substance result from the aggregation of the atoms rather than attributes of the atoms themselves].


Teaching resources

Where to start?

Start by bringing elements to life. Place various elements around the classroom e.g. iron, helium, silver and graphite. Ask students to record their appearance and state of matter. Ask students to locate the elements on the periodic table. What is the relationship between the position on the periodic table and their physical properties? Where are metals and non-metals? Where are shiny things located? Now make students learn the first 20 elements and chant them back as a whole class –  they will enjoy this more than you might think!

Discovery of elements

Share some of the fascinating stories behind the discovery of some elements e.g. phosphorous was discovered after boiling urine. This oeriodic table shows element discovery by country.

Elements of the periodic table – The Chemist’s Castle

KS3 worksheet on elements and their symbols. Students read a story about a chemist’s castle. It lists elements for them to find in the periodic table. The activity asks students to use symbols and names for elements. This is a fun and creative way to introduce students to elements and where they are located in the periodic table. Students can write their own stories, using their own choice of elements. (PDF)

Introducing compounds

One of the best ways to introduce the concepts of chemical reactions, mixtures, elements and compounds is to perform the classic demonstration of reacting iron with sulphur. This is a powerful way for the students to visualise that the product, iron (II) sulphide, bears no resemblance to either sulphur or iron.  

Building models of atoms, elements and compounds

KS3 activity on atoms, elements and compounds. Many GCSE and even A Level students are not clear on the difference between atoms, elements, compounds and molecules. This simple activity supports an understanding of these concepts. Students use a simple billiard ball model to build elements, compounds and molecules. The activity can be extended for students to build models of molecules from chemical formulae and is easy to access. If you are feeling adventurous try creating particles from marshmallows. (PDF)

Element, mixture or compound?

Key Stage 3 worksheet to identify elements, mixtures and compounds from particle pictures. This is a quick diagnostic task to see if students can use particle pictures to represent elements, mixtures and compounds. (PDF)

Thinking deeper

  1. Does a single atom of copper in a wire have similar or different properties to a single atom of copper vapour?
  2. How could you prove that glucose is not an element?
  3. How many elements, compounds and atoms are here: CH3COOH?
Further reading
  1. Particle pictures and the particle model
  2. Diffusion
  3. Elements mixtures and compounds
  4. Separating techniques
  5. Solutions
  6. Density

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