Elements, Compounds, Elements, Compounds, MixturesMixtures

Warm Up ActivityWarm Up ActivityThis picture show the atoms that

are present in the air.

1. Which ones are elements? 2. How can you tell?

What do we call these things?

An Atom

3 Atoms

What do we call these things?

6 Atoms of 3 different elements.

What do we call these things?

A Molecule of an element

• 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.

What do we call these things?

A Molecule of a compound

2 molecules of a compound

* Notice that these molecules have different atoms in them, so they are compounds, not elements.

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

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

Finally, just to confuse you even more, science teachers like talking about

ParticlesA 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 want to be exact about the type of things being described.

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.

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.

Since there is just one atom, you would write: Ar

Since there are two atoms of the same element, you would write O2

Since there are different elements, you would list both: H2O.

Ar

OH

H

Since there’s 2 oxygen atoms, you write a “2” after the O

O

O

If there’s just one atom, don’t put a number after it!

(Gas)

One Element The Same Element(Solid)

Notice that both examples are made up of only one type of atom. That’s why it is an element.

This one likes to go round in pairs as a gas (molecules)

Another element A mixture of two elements

Notice the mixture has more than one type of atom in it.

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.

Element, Compound or Mixture ?

Element

Element, Compound or Mixture ?

Element

Element, Compound or Mixture ?

Mixture of different elements

Element, Compound or Mixture ?

Mixture of different elements

Element, Compound or Mixture ?

Compound

Element, Compound or Mixture ?

Compound

Element, Compound or Mixture ?

A mixture of a compound and an element