5.1 – Light and Quantized Energy – Part 3

• OBJECTIVES: Students will be able to (SWBAT)

1. Calculate the energy of a wave

2. Explain how an emission spectrum helps to identify an

elementelement

• 5 lecture/10 reading questions

• 5-sentence summary

Notes: 5.1 – Light and Quantized

Energy – Part 3

Higher frequency = Higher energy

The colors have a specific

wavelength/frequency

VIOLET HAS SHORTEST

WAVELENGTH �

HIGHEST FREQUENCY �

MOST ENERGY

RED HAS LONGEST

WAVELENGTH �

LOWEST FREQUENCY �

LEAST ENERGY

Photon

• A particle of electromagnetic radiation with

no mass and a specific amount of energy

Planck’s Energy of a Photon Equation

• Ephoton = h×ν

– Energy of a photon = Planck’s constant × frequency

• Planck’s constant = 6.626×10-34 J·sPlanck’s constant = 6.626×10 J·s

• Energy is measured in Joules (J) or kilojoules (kJ)

• Energy and frequency have a direct relationship (E ↑,

ν ↑ or E ↓ , ν ↓)

Energy from the Wavelength

• Energy can also be calculated from the

wavelength of a photon/wave

photon

h×cE =

λ

• Energy and wavelength have an inverse

relationship

photonE =λ

Converting from kJ � J

• Attach “×103 J” to any value that is in kJ

• Practice:

– 3.1 kJ � J 3.1 ×103 J– 3.1 kJ � J

– 0.086 kJ � J

– 2.0×10-5 kJ �J

3.1

0.086

2.0×10-5

×103 J

×103 J

×103 J

=2.0×10-2 J

Higher frequency = Higher energy

Gamma rays

are the

highest

Radio waves

are the

lowest

energy rays highest

energy rays

Emission Spectra

• White light, with all the frequencies of all the

colors, is continuous (no dark areas)

• Emission Spectra is when some of the colors

are emitted or released but others are not (so

you see dark areas)

What causes the different colors?

What do you think the bulbs are made

of?

Atomic Emission Spectra

• Each element has a very specific emission

spectra (different bands of colors)

• An element’s emission spectra can be used to

identify the element

• Guess which element is giving the spectrum

below?below?

HYDROGEN

Why do you think each element has a

different spectrum?

Key Vocabulary Revisited

1. Atomic emission spectra

2. Frequency

3. Photon

HIGHER MEANS MORE ENERGY

PARTICLE WITH NO MASS WITH A SPECIFIC

AMOUNT OF ENERGY

4. Electromagnetic radiation

5. Wavelength

6. Electromagnetic spectrum

AMOUNT OF ENERGY

ALL FORMS OF ENERGY, INCLUDING LIGHT

LONGER MEANS SLOWER

SHOWS ALL THE FORMS OF RADIATION

INCLUDING THE COLORS OF VISIBLE LIGHT

Key Vocabulary Revisited

1. Atomic emission spectra

2. Frequency

3. Photon

4. Electromagnetic radiation

5. Wavelength

6. Electromagnetic spectrum