2.3 Electron spectrum

The line of the emission spectrum of hydrogen converge, what does that mean?

They become progressively closer as the frequency of energy of the emission lines increase

What is the energy required to ionise the electron?

The ionisation energy equivalent to the transition n=1 to n=infinity

Which electron transition in a hydrogen atom releases the most energy (1 mark) a. n=2 n=1 b. n=4 n=2 c. n=6 n=3 d. n=7 n=6

A

What is the difference between a line and a continuous spectrum?

A continuous spectrum has all colours/wavelengths/frequencies whereas a line spectrum has only (lines of) sharp/discrete/specific colours/ wavelengths/frequencies;

8. Which statement is correct about a line emission spectrum? a. Electrons neither absorb nor release energy as they move from low to high energy levels. b. Electrons absorb energy as they move from high to low energy levels. c. Electrons release energy as they move from low to high energy levels. d. Electrons release energy as they move from high to low energy levels.

C

List the following types of electromagnetic radiation in order of increasing wavelength (shortest first). I. Yellow light II. Red light III. Infrared radiation IV. Ultraviolet radiation

IV < I < II < III/ ultra violet radiation < yellow light < red light < infrared radiation;

White light is composed of a continuous spectrum, what does that mean?

It is composed of visible light of a certain range of wavelengths.

What is an emission spectrum?

It is made up of separate discrete lines

Which series is shifted towards the the highest frequency?

Lyman series transition to n=1

Which equation links the wave and particle character of light

Planck's equation E=hf E is the energy of a photon

How are the Lyman series formed?

They are formed as excited electrons from higher energy levels fall back to the second energy level

The thinning of the ozone layer increases the amount of UV-B radiation that reaches the Earth's surface. Type of Radiation Wavelength / nm UV-A 320-380 UV-B290-320 Based on the information in the table above explain why UV-B rays are more dangerous than UV-A.

UV-B radiation has shorter wavelength; hence, has higher energy; increases risk of damage to skin cells/OWTTE/causes cancer; 3

Why do light from atoms with excited electrons show a emission spectrum with lines at specific wavelengths?

When the excited electrons return to the ground state they emit light with a specific wavelength related to the energy difference between the two orbits.

When is an atom or electron said to be in the excited state?

When they have absorbed a photon with exactly the amount of energy needed to jump to the next orbit

Light can also be described by a particle model which treats light as a stream of photons. What is a photon

a tiny discrete package of light energy

Light can be described as a wave. What is the wave equation that relates the frequency wavelength and speed

c=f x wavelength

What is the wavelength

distance between two neighbouring crests or throughs of a wave

Do atoms with electrons in the ground state emit light?

no

What is frequency?

the number of waves which pass a point in a second (s-1)