KS3 Science · Chemistry
Elements, atoms and compounds
Five short lessons. Look at the picture, learn three things, then play.
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Key words
Atom The smallest particle of an element that can exist
Element A substance made of only one type of atom
Compound Two or more elements chemically joined together
Molecule A group of two or more atoms joined together
Mixture Two or more substances mixed together, not joined
Chemical symbol One or two letters that stand for an element
Chemical formula Symbols and numbers that show the elements in a substance and the ratio of their atoms
Dalton’s model The idea that atoms are tiny solid balls that cannot be broken down
Particle diagram A drawing that shows each atom as a circle
Property What a substance is like, such as its colour or whether it is magnetic
Chemical reaction A change that rearranges atoms to make new substances
Periodic table The chart that lists all the elements
Oxide A compound of an element with oxygen
Chloride A compound of an element with chlorine
Sodium chloride The compound in table salt
Iron sulfide The compound made when iron and sulfur react
Carbon dioxide A compound with one carbon atom joined to two oxygen atoms
Pure substance A single element or a single compound, with nothing mixed in