Elements, Compounds, Elements, Compounds, MixturesMixtures

This 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 which happen to be of 3 different elements

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.

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.

Air is a mixture of elements such as oxygen, argon and nitrogen mixed with compounds such as carbon dioxide.

When 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 This a COMPOUND of two different elements

Notice there are two different types of atoms joined together. That’s what makes this a compound.

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 or Compound ?

Element

Element or Compound ?

Element

Element or Compound?

Compound

Element or Compound ?

Compound

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 ?

A mixture of a compound and an element