2.3.1 Describe the electromagnetic spectrum
Properties of Waves:
- electromagnetic radiation is one way that energy moves
- in this form energy travels in waves at the speed of light
Properties of Waves:
- wavelength - distance over which a wave's shape repeats (crest to crest or trough to trough)
- amplitude - distance from point of inflexion to crest/trough
- frequency - number of waves that occur per second
- higher frequency = higher energy
- lower wavelength = higher frequency
2.3.2 Distinguish between a continuous spectrum and a line spectrum
Continuous Spectrum:
Line Spectrum:
Continuous Spectrum:
- exhibits all wavelengths with a specified region (no gaps can be seen)
- not limited to visible light region
Line Spectrum:
- if elements are "excited", they absorb energy of certain frequencies only and emit the rest
- therefore if emitted radiation is split into spectrum (eg. by viewing through a spectroscope), it contains only emissions at particular wavelengths
2.3.3 Explain how the lines in the emission spectrum of hydrogen are related to electron energy levels
- electrons can be "excited" by adding electricity
- electron has energy to move further away from protons (jumps = "electron transitions")
- it doesn't want to stay there though, so it falls back down to the original energy level
- as it goes to a lower level (its ground state) from its excited state, it emits energy
- there are only a specific, limited number of amounts of energy that an electron can lose
- the fall down a specific distance will always give off the same specific amount of energy
- therefore we get specific lines in the spectra of each element that makes a pattern characteristic of each element
- energy levels are quantized
2.3.4 Deduce the electron arrangement for atoms and ions up to Z=20
Eg.) For sodium (Na) and its ion (Na+):
Na 2, 8, 1
Na+: 2, 8
- electron arrangement is a listing, in order, of the number of electrons in each energy level (takes into account the number of electrons gained or lost if it's an ion)
Eg.) For sodium (Na) and its ion (Na+):
Na 2, 8, 1
Na+: 2, 8