AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
The development of the model of the atom (common content with physics): Later experiments led to the idea that the positive charge of any nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name proton was given to these particles.
Once the nuclear model was accepted, scientists still needed to explain the positive charge inside the nucleus.
- 2 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Once the nuclear model was accepted, scientists still needed to explain the positive charge inside the nucleus. Later experiments showed that the positive charge of any nucleus is not a single indivisible quantity but can be split into a whole number of equal positive units. Each unit is a particle called a proton, and the number of protons equals the number of positive charges on the nucleus. For example, a helium nucleus has a charge of 2+ because it contains two protons, while hydrogen has 1+ because it contains one proton. This idea explained why different elements have different nuclear charges and helped establish the proton as a fundamental part of every atom.
What earns the marks
- Later experiments showed that nuclear positive charge is not continuous but comes in whole-number multiples of a single positive charge.
- The positive charge of a nucleus can be subdivided into smaller particles, each carrying the same amount of positive charge.
- The model applies to any nucleus, so a nucleus with charge 2+ contains two protons and a nucleus with charge 1+ contains one proton.
Common mistakes and how to put them right
Saying the nucleus contains positive charge but no particles.
Put it right by stating that the positive charge is carried by protons.
Thinking the number of protons equals the mass number.
Put it right by explaining that protons equal the atomic number, while neutrons also contribute to mass.
Confusing the charge of the nucleus with the overall charge of the atom.
Put it right by remembering that while the nucleus is positive, the whole atom is neutral because of the electrons.
Exam tips
- Use the phrase 'whole number of smaller particles' when describing the subdivision of nuclear charge, and link it to the name proton.
- When giving an example, state the charge and the number of protons together, such as a 2+ nucleus containing two protons.
- If asked about evidence, explain that experiments measured nuclear charge and found it changed in whole-number steps, supporting equal-charge particles.
Try the lesson
The start of the The development of the model of the atom (common content with physics): Later experiments led to the idea that the positive charge of any nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name proton was given to these particles. lesson, made from checked teaching notes for this specification point.
Have a go first
According to the nuclear model developed from later experiments, what name is given to the small positive particles that make up the positive charge of a nucleus?
Listen
Once the nuclear model was accepted, scientists still needed to explain the positive charge inside the nucleus. Later experiments showed that the positive charge of any nucleus is not a single indivisible quantity but can be split into a whole number of equal positive units. Each unit is a particle called a proton, and the number of protons equals the number of positive charges on the nucleus. For example, a helium nucleus has a charge of 2+ because it contains two protons, while hydrogen has 1+ because it contains one proton. This idea explained why different elements have different nuclear charges and helped establish the proton as a fundamental part of every atom. A strong answer earns marks for these points. Later experiments showed that nuclear positive charge is not continuous but comes in whole-number multiples of a single positive charge. The positive charge of a nucleus can be subdivided into smaller particles, each carrying the same amount of positive charge. The model applies to any nucleus, so a nucleus with charge 2+ contains two protons and a nucleus with charge 1+ contains one proton. A common slip: Saying the nucleus contains positive charge but no particles. Instead, stating that the positive charge is carried by protons. Exam tip: Use the phrase 'whole number of smaller particles' when describing the subdivision of nuclear charge, and link it to the name proton.
See it
Key words
Say what each word means before you turn the card.
proton
Try answering aloud or in your head before turning the card.
nuclear charge
Try answering aloud or in your head before turning the card.
See every definition
- proton
- The name given to the smaller particles into which the positive charge of any nucleus could be subdivided, each having the same amount of positive charge.
- nuclear charge
- The positive charge of a nucleus, which can be subdivided into a whole number of smaller particles each having the same amount of positive charge.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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