What it does
Everything is made of particles, and the kind of particles decides what sort of matter it is. This page deals you everyday things such as air, table salt, copper wire, rust or brass, and three bins: Element, Compound and Mixture. Drag each thing into its bin, or tap it and then tap a bin. Tap a thing to see a particle picture: coloured balls for atoms, joined into molecules where they are joined.
- An element has one kind of particle, made of one kind of atom (oxygen gas is O₂, still only oxygen).
- A compound has one kind of particle with two or more kinds of atom joined in a fixed ratio (water is always H₂O).
- A mixture has two or more kinds of particle mixed but not joined (air).
It follows Class 8 Science, Nature of Matter. Before this, states of matter shows how particles move; after it, build an atom and formula writer go inside the atom and the formula.
How to use it
- Choose a Level. Class 8 has three bins. Class 9 splits Mixture into homogeneous (same all through) and heterogeneous (not the same all through).
- Drag a thing into a bin, or tap it and then a bin. A right answer gets a tick; a wrong one is counted and stays in the tray.
- Use the particle picture to decide.
- New set deals fresh things. Answer the Check yourself questions.
Worked example
Take pure water, tap water and iron sulphide. Pure water shows only H₂O: one kind of particle with two kinds of atom joined, so a compound. Tap water adds a few dissolved calcium carbonate particles: two kinds of particle, so a mixture (a homogeneous one at Class 9). Iron filings stirred with sulphur are a mixture, and a magnet pulls the iron out. Heat them and they join into FeS, a compound, and the magnet no longer works.
Tips
- “Pure” on a shop label is not the same as pure in science, which means one kind of particle.
- An alloy such as brass is a mixture, because the amounts of each metal can change.
FAQ
Why is air a mixture when oxygen is an element? Air holds several kinds of particle, none joined to the others, in changing amounts.
Is anything stored? No. Everything stays on the page.
Where the numbers come from
- Elements, compounds and mixtures, homogeneous and heterogeneous mixtures, chemical formulae: standard school chemistry found in any textbook. Element symbols and formulae follow IUPAC.
- Everyday things are simplified to their main particles (for example air as nitrogen, oxygen, argon and carbon dioxide; tap water as water with a trace of dissolved calcium carbonate). The shares and atom colours are rounded, made-up teaching values.
- Checked by tests: the bin of every thing is worked out from its particles and compared with a hand-made answer list, and every formula is read back into atom counts.
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-10.