Elements, compounds and mixtures

Elements, compounds and mixtures

What's the difference?

Multiple Choice

A 24 carat gold bar is an example of an element. This means it is made of...

• Only one atom

• Only gold atoms

• Only two different atoms

• A mixture of atoms

Multiple Select

Which two of these could represent an element?

Elements are represented on the Periodic Table by their own symbol...

• Copper (Cu)

• Oxygen (O₂)

Compounds contain more than one element:

• Copper oxide (CuO)

• Methane (CH₄)

Multiple Select

Which two of these are elements?

• Water (H₂O)

• Hydrogen (H₂)

• Salt 🧂 (NaCl)

• Iron (Fe)

• Carbon dioxide (CO₂)

What is the difference between a compound and a mixture?

In a compound different atoms are bonded together.

Multiple Select

Which two of these could represent a compound?

Multiple Choice

Imagine I fill a balloon with some hydrogen gas, then some oxygen gas is added. They do not react. This is an example of..

• An element

• A mixture

• A compound

Mixtures can be easily separated

For example, by sieving, filtering or evaporating

Multiple Select

Which two of these are true?

• In a mixture, all the chemicals have reacted together and bonded

• In a compound the elements have reacted together and bonded

• To make a mixture, the chemicals must be combined in the same amounts every time

• In a compound, the atoms are always combined in a specific ratio

Multiple Select

A mixture can easily be separated, a compound cannot. Which of these is a compound?

• Salt water

Multiple Choice

Which of these mixtures could easily be separated using a magnet?

• Water and sand

• Sand and salt

• Iron and sand

• Salt and water

Multiple Select

Which two of these common chemicals are not mixtures?

• Tap water

• Air

• Milk

• Copper

• Oxygen

Multiple Select

Which two of these mixtures could easily be separated using a filter?

• Coffee grinds and coffee

• Salt and water

• Sand and salt

• Sand and water

• Oil and water

Multiple Choice

What is evaporation (or crystallisation) usually used for?

• To get clean water from dirty water

• To separate a soluble solid (like salt or minerals) from water

• To separate hydrogen from water

• To separate an insoluble solid (like sand) from water