D. Crowley, 2007

To be able to recognise elements, compounds and mixtures

Remember, elements and compounds can be represented using formula

The number represents the ratio of atoms present

The small number always represents the number of atoms for the element to the left of it

Finally, elements always begin with a CAPITAL (but they may have two or three small letters after them too)!

CO2

1 x C (carbon); 2 x O (oxygen) = carbon dioxide

NaCl1 x Na (sodium); 1 x Cl (chlorine) = sodium chloride

CaCO3

1 x Ca (calcium); 1 x C (carbon); 3 x O (oxygen) = calcium carbonate

C6H12O6

6 x C (carbon); 12 x H (hydrogen); 6 x O (oxygen) = glucose

Using the worksheet, complete the missing blanks

Once you have done this, complete the second task

This is timed - you have fifteen minutes! If you have completed this, ensure all your work is stuck in!

Rust is formed when iron objects are left out in the air. The iron reacts with the oxygen in the air, forming iron oxide. Rust be can turned back into iron, by mixing it with carbon and heating it. I think rust is _______________ (an element / a mixture / a compound) because…

There are a number of different gases in the air. The main ones are nitrogen and oxygen, but there are also small amounts of argon, carbon dioxide and water vapour. I think air is _______________ (an element / a mixture / a compound) because…

Helium is a gas. There are tiny amounts of helium in the air. Helium does not burn, and will not react with any other chemicals. It cannot be split up by chemical reactions. It think helium is _______________ (an element / a mixture / a compound) because…

Evaporating salty water results in common salt being left behind. This salt is called sodium chloride, and is made up of two elements, sodium (Na) and chlorine (Cl). I think salt is _______________ (an element / a mixture / a compound) because…

Rust is formed when iron objects are left out in the air. The iron reacts with the oxygen in the air, forming iron oxide. Rust be can turned back into iron, by mixing it with carbon and heating it. I think rust is a compound because it has iron and oxygen which are chemically bound. The iron oxide has new properties too

There are a number of different gases in the air. The main ones are nitrogen and oxygen, but there are also small amounts of argon, carbon dioxide and water vapour. I think air is a mixture because it has a variety of elements which make it up, which are not chemically bound (it also has some compounds which make up the mixture)

Helium is a gas. There are tiny amounts of helium in the air. Helium does not burn, and will not react with any other chemicals. It cannot be split up by chemical reactions. It think helium is an element because it is made up of just one type of atom, and cannot be split into anything smaller

Evaporating salty water results in common salt being left behind. This salt is called sodium chloride, and is made up of two elements, sodium (Na) and chlorine (Cl). I think salt is a compound because the sodium and chlorine are chemically bound. They also have new properties (so different in fact that NaCl is edible (table salt)) whilst the elements which make up this compound are not safe to injest

In small groups your final task is to make a suitable poster (in aid of revision) to help us distinguish between elements, compounds and mixtures.

You may wish to define the three; show particle models and give examples

Make it colourful, easy to read and informative…

Remember: an element is made up of just one type of atom

A compound is two or more elements which are chemically bound together…

A mixture is made from different substances which are not chemically bound

Element CompoundElement Mixture Mixture