Elements, Compounds, Mixtures

1. Elements, Compounds, Mixtures

2. Warm Up Activity • This picture show the atoms that are present in the air. • Which ones are elements? • How can you tell?

3. What do we call these things? An Atom 3 Atoms

4. What do we call these things? 6 Atoms which happen to be of 3 different elements

5. What do we call these things? A Molecule • We don’t call it “2 atoms joined together” we say it is one molecule. • Since the atoms are the same, it is also an element, not a compound.

6. What do we call these things? * Notice that these molecules have different atoms in them, so they are compounds, not elements. A Molecule of a compound 2 molecules of a compound

7. What about when all the atoms are stuck together like in a solid element?

8. This is just a load of atoms in a solid element, it is not a big molecule

9. Finally, just to confuse you even more, science teachers like talking about Particles A particle is just a fancy name for individual things. These individual things could be atoms, molecules, lumps of soil, grains of sand, or bits of metal. It doesn’t matter because particle is just a general word which is used when we don’t (or can’t) want to be exact about the type of things being described.

10. A good example of when science teachers use the word particle is when talking about air. Air is a mixture of elements such as oxygen, argon and nitrogen mixed with compounds such as carbon dioxide, or you can say that air is a mixture of particles.

11. Some of the elements in air go around as single atoms (such as argon). Or as molecules such as oxygen. Compounds go around as molecules.

12. Since there is just one atom, you would write: Ar Ar If there’s just one atom, don’t put a number after it! O Since there are two atoms of the same element, you would write O2 O Since there’s 2 oxygen atoms, you write a “2” after the O Since there are different elements, you would list both: H2O. H O H

13. One Element The Same Element (Gas) (Solid) Notice that both examples are made up of only one type of atom. That’s why it is an element.

14. Another element A mixture of two elements This one likes to go round in pairs as a gas (molecules) Notice the mixture has more than one type of atom in it.

15. This a COMPOUND of two different elements This is just a mixture of two elements Notice there are two different types of atoms joined together. That’s what makes this a compound. Notice in a mixture the all the molecules are not the same.

16. Element, Compound or Mixture ? Element

17. Element, Compound or Mixture ? Element

18. Element, Compound or Mixture ? Mixture of different elements

19. Element, Compound or Mixture ? Mixture of different elements

20. Element, Compound or Mixture ? Compound

21. Element, Compound or Mixture ? Compound

22. Element, Compound or Mixture ? A mixture of a compound and an element