New
New
Year 10
AQA
Higher

The mole

I can describe what a mole is and its link with the Avogadro constant.

New
New
Year 10
AQA
Higher

The mole

I can describe what a mole is and its link with the Avogadro constant.

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Lesson details

Key learning points

  1. Chemical amounts are measured in moles (mol).
  2. One mole of particles of a substance is defined as the Avogadro constant number of particles.
  3. The number of particles (atoms, ions, molecules etc.) in one mole of a substance is always the same.
  4. Use of Avogadro's number to calculate the number of particles of substance when number of moles is known and vice versa.
  5. The mass of one mole of a monatomic element is equal to the relative atomic mass of that element measured in grams.

Common misconception

The number one mole represents can be difficult for pupils to grasp and appreciate.

Show many real world examples of 6.02 × 10²³ examples of something - that many basketballs would form a planet the size of the Earth.

Keywords

  • Mole - A mole of something is 6.02 × 10²³ of it. The mass of a mole of a substance is its relative mass expressed in grams.

  • Relative formula mass - The relative formula mass (RFM) of a substance is the sum of the relative atomic masses of all the atoms in a formula.

  • Avogadro's constant - Avogadro's constant is the number of particles in one mole of a substance (6.02 × 10²³ mol⁻¹)

Use a visualiser to model how to annotate questions and layout the work on lined paper. Use colour-coding to assist. For more ideas, try looking at the Year 9 Maths unit 'Expressions and formulae'
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
The relative atomic mass for this element is .
An image in a quiz
Correct Answer: 63, sixty three
Q2.
Match each keyword to the correct description.
Correct Answer:element,a substance made up of only one type of atom

a substance made up of only one type of atom

Correct Answer:compound,two more or elements chemically bonded together

two more or elements chemically bonded together

Correct Answer:ion,a particle with an electrical charge due to the gain/loss of electrons

a particle with an electrical charge due to the gain/loss of electrons

Correct Answer:molecule,a particle consisting of two or more atoms joined by covalent bonds

a particle consisting of two or more atoms joined by covalent bonds

Correct Answer:diatomic,two atoms chemically bonded together

two atoms chemically bonded together

Q3.
Which of the following formulae are for substances that contain ionic bonds?
SiO₂
CO₂
Correct answer: NaBr
CH₄
Correct answer: Fe₂O₃
Q4.
Which formulae indicate substances that are simple molecular in structure?
CaO
Correct answer: P₂O₅
LiF
Correct answer: H₂
Correct answer: H₂O
Q5.
The chemical formula for sodium bromide is .
Correct Answer: NaBr
Q6.
The relative formula mass of magnesium chloride, MgCl₂, is .
Correct Answer: 94, 24 + 35.5 + 35.5, 24 + 70, 24.3 + (2 * 35.5), ninety four

6 Questions

Q1.
Which of the following is the correct value for Avogadro's constant?
6.02 × 10²²
6.02 × 10⁻²³
6.02 × 10⁻²²
Correct answer: 6.02 × 10²³
Q2.
Which of the following correctly shows the relationship between the number of particles, number of moles and Avogadro's constant (6.02 × 10²³)?
number of moles = (6.02 × 10²³) ÷ number of particles
Correct answer: number of moles = number of particles ÷ (6.02 × 10²³)
number of moles = number of particles × (6.02 × 10²³)
number of moles = (6.02 × 10²³) ÷ number of particles
Q3.
There are moles in 5.42 × 10²³ particles of calcium carbonate. Give your answer to 3 significant figures.
Correct Answer: 0.900
Q4.
Match the chemical formula to the correct type of particle.
Correct Answer:He,atom

atom

Correct Answer:CH₄,molecule

molecule

Correct Answer:I₂,molecule

molecule

Correct Answer:KBr,formula unit

formula unit

Correct Answer:AgCl,formula unit

formula unit

Correct Answer:Fe,atom

atom

Q5.
Match the values that have an equivalent number of particles.
Correct Answer:0.5 mol,6 g of carbon

6 g of carbon

Correct Answer:46 g of sodium,62 g of phosphorus

62 g of phosphorus

Correct Answer:1.5 mol,30 g of neon

30 g of neon

Correct Answer:27 g of beryllium,84 g silicon

84 g silicon

Correct Answer:2.5 mol,35 g of nitrogen

35 g of nitrogen

Q6.
The mass of one atom of nickel is 9.75 × 10⁻²³ grams. What is the mass of 1.25 mol of nickel in grams? Give your answer to 3 s.f.
Correct Answer: 73.4