What You Need to Know

Key Concept Diagram

Electrons occupy specific energy levels; each element has a unique set of levels

When electrons fall from higher to lower levels, they emit photons of specific wavelengths

Emission spectrum: bright lines on dark background (light emitted by excited atoms)

Spectroscopy identifies elements in stars and distant objects by their spectral fingerprint

Key Vocabulary

Energy level

A specific, quantised amount of energy that an electron can have in an atom

Photon

A particle of light energy emitted or absorbed when an electron changes energy level

Emission spectrum

The pattern of bright spectral lines produced by light emitted from excited atoms

Spectroscopy

The study of spectra to identify elements and their properties

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

Why does each element produce a unique emission spectrum?

Each element has a different colour of light Each element has a unique set of electron energy levels, producing specific wavelengths Each element absorbs light differently from its neighbours in the periodic table Elements produce spectra only when mixed with other elements

Question 2

When an electron in an excited atom falls to a lower energy level, it:

Absorbs a photon of light Splits into two particles Emits a photon of light Moves to the nucleus

Question 3

Spectroscopy is used to identify elements in distant stars because:

Stars emit only one colour of light Light travels faster than other signals All stars contain the same elements Each element's spectral lines are unique and can be identified at any distance

Atomic Emission Spectra