New
New
Year 10
AQA
Foundation

Why chemical reactions happen

I can explain chemical bonding in terms of the transfer or sharing of electrons.

New
New
Year 10
AQA
Foundation

Why chemical reactions happen

I can explain chemical bonding in terms of the transfer or sharing of electrons.

Lesson details

Key learning points

  1. There are five different types of substance: monatomic, simple covalent (molecules), giant covalent, ionic and metallic
  2. The outer shell in most atoms can hold 8 electrons but, in hydrogen and helium, it can only hold 2 electrons.
  3. Most atoms increase their stability by forming bonds with other atoms so that they have a full outer shell of electrons.
  4. Some atoms will share electrons with other atoms to increase their stability.
  5. Some atoms will lose or gain electrons to increase stability forming cations or anions, respectfully.

Common misconception

Atoms react because they 'want' to gain a fuller outer shell of electrons – atoms don't have feelings. Monatomic means one atom and may be confused with the term element, which means one type of atom.

Take care with language and avoid personifying the atoms. Make sure that definitions and terms are used correctly.

Keywords

  • Molecule - A molecule is a particle consisting of a fixed number of (two or more) non-metal atoms covalently bonded together.

  • Noble gas configuration - When an atom has a full outer shell of electrons, it has a noble gas electron configuration.

  • Outer shell - The outer shell is the highest energy level in an atom and is usually the furthest from the nucleus.

  • Cation - a particle with a positive charge.

  • Anion - a particle with a negative charge.

This is an introductory lesson, so emphasise the importance of why chemical reactions happen - bonding and structure will be covered in more details in other lessons.
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.
Match the following terms to the correct definition.
Correct Answer:atomic mass,Relative mass of an atom, the total mass of its protons and neutrons.

Relative mass of an atom, the total mass of its protons and neutrons.

Correct Answer:atomic number,Number of protons in the nucleus of an atom of an element.

Number of protons in the nucleus of an atom of an element.

Correct Answer:atom,The smallest particle of an element that can exist.

The smallest particle of an element that can exist.

Correct Answer:molecule,A group of atoms chemically bonded together.

A group of atoms chemically bonded together.

Q2.
Which of the following are elements?
Correct answer: O₂
NH₃
CO
Correct answer: Co
Q3.
Oxygen has an atomic mass of 16 and an atomic number of 8. How many electrons does an atom of oxygen have?
Correct Answer: 8, eight
Q4.
Lithium is in Group 1, period 2 of the periodic table. It has an atomic number of 3. How many electrons are found in the outer shell of a lithium atom?
Correct answer: 1
2
3
8
Q5.
Which of the following are examples of diatomic molecules?
Correct answer: O₂
Correct answer: N₂
CO₂
CuCO₃
Q6.
Which of the following statements about subatomic particles are correct?
Electrons have a relative charge of +1.
Correct answer: Neutrons have no charge.
Protons and electrons are found in the nucleus of atoms.
Correct answer: Protons have a relative mass of 1.

6 Questions

Q1.
Match the following terms to the correct definitions.
Correct Answer:electron configuration,The arrangement of electrons in shells, in an atom or ion.

The arrangement of electrons in shells, in an atom or ion.

Correct Answer:outer shell,The highest energy level in an atom, contains electrons.

The highest energy level in an atom, contains electrons.

Correct Answer:cation,A particle with a positive charge.

A particle with a positive charge.

Correct Answer:anion,A particle with a negative charge.

A particle with a negative charge.

Q2.
In which of the following are electrons donated and accepted?
giant covalent substances
simple covalent substances
Correct answer: ionic substances
metallic substances
Q3.
Which of the following are monoatomic substances?
Correct answer: krypton, Kr
oxygen, O₂
carbon dioxide, CO₂
nitrogen, N₂
Correct answer: helium, He
Q4.
What type of bonding forms between non-metal atoms?
Correct Answer: covalent, covalent bonds, covalent bonding
Q5.
Why is an oxygen atom considered to be unstable?
Correct answer: It does not have a full outer shell of electrons.
The outer shell contains eight electrons.
Correct answer: The outer shell contains six electrons.
It has a full outer shell of electrons.
Q6.
Which of the following diagrams shows an ionic substance?
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz