Evidence of atomic structure
I can describe how alpha particles were used to show the size and nature of atomic nuclei.
- Year 11•
- Edexcel
Evidence of atomic structure
I can describe how alpha particles were used to show the size and nature of atomic nuclei.
Lesson details
Key learning points
- Background radiation is caused by unstable nuclei that are around us all of the time.
- Atoms are very small with a radius of about 1 × 10⁻¹⁰ m.
- The alpha particle scattering experiment (Rutherford, 1909) provides evidence for the size and nature of atomic nuclei.
- An atomic nucleus has a radius about 10 000 times smaller than that of an atom.
- Most of the mass of an atom is in its nucleus.
Keywords
Background radiation - the radiation in the surroundings of a particular place
Alpha particle - a small, positively charged particle which was used to discover the nucleus
Alpha scattering experiment - the experiment used to discover the atomic nucleus from the deflection of alpha particles fired at it
Nucleus - the central part of an atom which contains most of the mass and all of the positive charge
Common misconception
Atoms are visible under powerful optical microscopes.
Emphasise that atoms are far too small to see and our descriptions of atoms are models, based on evidence, that help us understand how they behave.
Licence
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.What happens to the particles in a liquid when its temperature increases?
Q2.What is the smallest component of an element?
Q3.Which of these are elements?
Q4.In which state are the particles in a substance most free to move around?
Q5.Match the particles to their descriptions.
electron - negatively charged particle found outside a nucleus
proton - positively charges particle found in a nucleus
neutron - particle with no charge found in a nucleus
atom - neutral particle
Q6.Starting with the largest, put these objects in order of mass.
Assessment exit quiz
6 Questions
Q1.Match each of the following terms used in nuclear physics to the correct definitions.
background radiation - the radiation in the surroundings at a particular place
alpha particle - a positively charged particle that is a type of radiation
alpha scattering experiment - an investigation to explore the structure of atoms
nucleus - the part in the middle of an atom which contains most of its mass
Q2.Which of the following are properties of an alpha particle?
Q3.Which of the following are classified as artificial sources of background radiation?
Q4.Match the results of the alpha particle scattering experiment (where a beam of alpha particles is fired at gold foil) to the corresponding conclusions made.
most pass straight through - most of an atom is empty space
some are deflected by large angles - there is a nucleus with a positive charge
a small number ‘bounce back’ - the nucleus contains most of the mass of the atom
Q5.Starting with the earliest, sort the following into date order.
Q6.Henri Becquerel discovered radiation in 1896 when investigating uranium salts. What properties did the radiation have that lead to the discovery?
