GCSE · Physics · Edexcel · Spec 1PH0

Atomic/nuclear changes generate radiation

Radiation isn't just a 'radioactive' thing. There are two places it comes from and two directions it can go. Can you place them all?

Physics · Radiation

One sort, two switches

Pick a change, then pick the box you think it belongs in. Then flip the switch and sort them all again.

Is this change in the atom's electrons, or in the nucleus?

Still to sort

Change in the atom (0)

An electron moves between energy levels (or is removed from the atom).

Where the line is: Look for an electron changing. If the nucleus itself is rearranging or being changed, it belongs in the other box.

Change in the nucleus (0)

The nucleus rearranges itself or is changed.

Where the line is: No electron levels here. The thing changing is the nucleus.

4 of 4 still to sort.

Sort the same four changes twice. First by where they happen, then by which way the radiation goes. Commit before you read the reason.

Physics · Atoms

Reason it through

Why does an atom give out electromagnetic radiation when an electron drops to a lower energy level?

Link 1 of 4

First link · your turn

An electron moves from a higher energy level to a lower one. What has happened to the atom's energy?

Locked — reveal the link above first

Physics · Frequency

Put the radiation in order

the frequency of the radiation given out

1 · Highest frequency3 · Lowest frequency

An electron makes a small drop between energy levels, giving out visible light
An unstable nucleus rearranges itself and loses energy, giving out gamma radiation
An electron makes a larger drop between energy levels, giving out ultraviolet

Physics · Radiation

Which idea sounds like yours?

A friend says: 'Radiation is what radioactive stuff gives off. It comes out of nuclei and that's it.'

Which is closest to what you think right now?

Only radioactive nuclei give out radiation. Atoms and their electrons don't.Atoms and nuclei can both give out radiation, and both can also be changed by absorbing it.Radiation only ever comes out of atoms and nuclei. Nothing is ever taken in.Every change gives out the same kind of radiation, so the size of the change doesn't matter.

How sure are you?

I'm sureI think soI'm guessing

Only radioactive nuclei give out radiation. Atoms and their electrons don't.

This is a common misconception

That's the tempting one, but atoms give out electromagnetic radiation too. When an electron moves from a higher energy level to a lower one, the atom loses energy and emits it as radiation, visible light or ultraviolet for example. Nuclei are one source, not the only one.

Atoms and nuclei can both give out radiation, and both can also be changed by absorbing it.

This matches the evidence

Yes. Two places (the atom's electrons and the nucleus), two directions (radiation out and radiation in), and every one of the four combinations really happens.

Radiation only ever comes out of atoms and nuclei. Nothing is ever taken in.

This is a common misconception

It runs the other way too. Absorbing radiation can move an electron up to a higher energy level, or remove it from the atom altogether (ionisation). Absorbing high-energy radiation can also change a nucleus.

Every change gives out the same kind of radiation, so the size of the change doesn't matter.

This is a common misconception

The size of the energy change matters. The larger the energy change, the higher the frequency, which is why changes in atoms and nuclei give out radiation over a wide range of frequencies, with gamma at the very high-frequency end.

Two places, two directions, and all four boxes are filled. The bigger the energy change, the higher the frequency.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Atoms give it out. Nuclei give it out. And both can take it in.

What you need to know

Changes in atoms and changes in nuclei can both generate electromagnetic radiation, across a wide range of frequencies.
In an atom, an electron moves from a higher energy level to a lower one, and the atom emits the lost energy as radiation.
The larger the energy change, the higher the frequency of the radiation, for example visible light or ultraviolet.
Have a goSam says: 'A tiny energy drop and a huge one give out exactly the same frequency. Energy is energy.' Do you back Sam?
No. The larger the energy change, the higher the frequency.
Frequency follows the size of the energy change, so a tiny drop and a huge one cannot give the same frequency.
An unstable nucleus can rearrange itself, lose energy, and emit gamma radiation.
Have a goA nucleus rearranges and loses energy. Is it the electrons or the nucleus changing here, and what might it emit?
The nucleus is changing, and it can emit gamma radiation.
Gamma comes from an unstable nucleus rearranging, not from electrons moving between energy levels.
Gamma sits at the very high-frequency end of the electromagnetic spectrum.
It runs the other way too: absorbing radiation can move an electron up to a higher energy level.
Have a goAn electron has just jumped UP an energy level. Did radiation go out of the atom or in?
In. The radiation was absorbed.
Moving up is the reverse of dropping: a drop gives radiation out, so a climb is what absorbing radiation can cause.
Absorb enough and an electron can be removed from the atom altogether, which is called ionisation.
Absorbing high-energy radiation can also change a nucleus.
So: two places (atom, nucleus) and two directions (out, in), and all four combinations happen.

The big picture

Changes in atoms (an electron moving between energy levels) and changes in nuclei (an unstable nucleus rearranging) both give out electromagnetic radiation, across a wide range of frequencies. Absorbing radiation can cause changes in atoms and nuclei too, so both places work in both directions.

Key points

1Atoms: an electron moving from a higher energy level to a lower one makes the atom emit radiation, and a bigger energy change means a higher frequency.

2Nuclei: an unstable nucleus that rearranges and loses energy can emit gamma, at the very high-frequency end of the electromagnetic spectrum.

3Absorbing radiation can lift an electron to a higher level, remove it from the atom (ionisation), or, for high-energy radiation, change a nucleus.

4Place (atom or nucleus) and direction (out or in) are two separate questions about any change.

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Worked example

Problem

An atom absorbs radiation and one of its electrons is removed from the atom altogether. (a) Is this a change in the atom or in the nucleus? (b) Is radiation given out or absorbed? (c) What is the process called?

⚠ Watch out

Thinking radiation only ever comes out of radioactive nuclei. Electrons dropping to a lower energy level give out electromagnetic radiation too, and radiation can go in as well: absorbing it can lift an electron up, remove it from the atom (ionisation), or change a nucleus.

🧠

Memory hook

Electron drops, radiation out. Electron climbs, radiation in. The bigger the drop, the higher the frequency, and gamma is right at the top.

✓

Check yourself

Without looking back: there are four boxes (atom or nucleus, crossed with radiation out or radiation in). Say what happens in each one.

Flashcards

(8)

What can generate electromagnetic radiation over a wide range of frequencies?

Changes in atoms and changes in nuclei.

What change in an atom makes it emit electromagnetic radiation?

An electron moves from a higher energy level to a lower one, and the atom emits the energy it lost as radiation.

How does the size of the energy change affect the radiation emitted?

The larger the energy change, the higher the frequency of the radiation, for example visible light or ultraviolet.

What can an unstable nucleus emit when it rearranges itself and loses energy?

Gamma radiation.

Where does gamma radiation sit on the electromagnetic spectrum?

At the very high-frequency end.

What can absorbing electromagnetic radiation do to an electron in an atom?

Move it to a higher energy level, or remove it from the atom altogether.

What is ionisation?

An electron being removed from the atom altogether, which absorbing radiation can cause.

What can absorbing high-energy radiation do to a nucleus?

Change it.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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One sort, two switches

Put the radiation in order

Which idea sounds like yours?

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