Page 9 - PRE-U STPM CHEMISTRY TERM 1

Chemistry Term 1 STPM
The Line Spectrum of Hydrogen 2013/P1/Q18(a)

2015/P2/Q4
1 When sunlight passes through a prism, the colours of the rainbow
are observed. This type of spectrum is known as a continuous 2016/P1/Q3, Q18(c)
spectrum because it contains all the possible wavelengths (or 2017/P1/Q2
CHAPTER
frequencies) of the visible light. 2018/P1/Q2, Q19(a)
2
~ 700 nm

Red

Violet
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T
Sunlight Tips
Exam
Exam
~ 400 nm
The Continuous Spectrum Continuous spectrum
contains all the wavelengths
2 However, when electricity is passed through a discharge tube that make up visible light.
filled with hydrogen gas at low pressure, a pink light is emitted.
ips
T
When this light passes through a prism or is observed through a Exam Tips
Exam
spectroscope a line spectrum is obtained.
The spectrum consists of a
few coloured lines, each
corresponding to a particular
Slits wavelength or frequency.
Prism (Red: 656.2 nm, blue-green:
486.1 nm, blue-violet:
434.0 nm and violet:
410.0 nm)

Blue- Blue-
Violet violet green Red

Gas discharge
tube containing
hydrogen 410.0 nm 434.0 nm 486.1 nm 656.2 nm
Line Spectrum of
Atomic Hydrogen
INFO
400 450 500 550 600 650 700 750
Wavelength

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