Elements, Compounds, Mixtures

Elements, Compounds, Mixtures

grade 8 science

Poll

Do you know the difference between an element, a compound, and a mixture?

• yes

• no

• kind of

Elements

• only one type of atom

• can be a single atom or more joined together (but always same type!)

Compounds

• two or more atoms bonded together

• different types of atoms

Mixtures

• two or more different substances physically combined

• can be easily separated

• each part has different properties

Poll

Can you explain what a pure substance is?

• yes

• no

• ummmm sort of

Pure Substance

• looks the same throughout

• elements or compounds

• if you can write a formula for it or it's an element then it's a pure substance!

Examples of Pure Substances:

• sugar C₁₂H₂₂O₁₁

• nitrogen N₂

• salt NaCl

• water (distilled) H₂O

Multiple Choice

Which of the following is a pure substance?

Multiple Choice

Which of the following is a pure substance?

Multiple Choice

Which of the following is a mixture?

Multiple Choice

Which of the following is a compound?

Multiple Choice

Which of the following is an element?

Multiple Choice

Which of the following is a pure substance?

Multiple Choice

Which is NOT a pure substance?

Multiple Choice

Which of the following is NOT a mixture?

Multiple Choice

Match the diagram to the correct formula.

• 3CO

• 3C₂O

• 3CO₂

Multiple Choice

Match the diagram to the correct formula.

• C₂H₄

• 2CH₄

• C₂H₈

Multiple Choice

Match the diagram to the correct formula.

• 3CL

• 2Cl₃

• 3Cl₂

Multiple Choice

Which diagram matches this formula: 2N₂ and 2O₂

Multiple Choice

How many different elements are in this diagram?

• 6

• 2

• 3

• 9

Multiple Choice

How many different elements are in this molecule?

• 33

• 3

• 22

• 12

Multiple Choice

Which diagram matches this formula? C₂H₂

Multiple Choice

Which a diagram of a water molecule? H₂O

Multiple Choice

Which diagram matches this formula? C₂H₄

Poll

How confident are you that you can tell the difference between elements, compounds, and mixtures?

The End

Questions?