1. Modern Atomic Model and EMR

2. OUTCOME QUESTION(S): C12-2-04 ENERGY AND ATOMIC MODELS
Explain average atomic mass using isotopes and their relative abundance.
Include: radioisotopes
Describe the electromagnetic spectrum in terms of frequency, wavelength, and energy.
Include: Plank’s Equation, quantum, photon
Understand the historical development of the Quantum Mechanical Model of the atom.
Describe how unique line spectra are created for each element.
Include: Bohr model
Vocabulary & Concepts
Spectroscopy Emission
Line spectrum

3. Wavelength and frequency are inversely related
Wavelength (λ - “lambda”): distance from point to the same point on the next wave.
Frequency (ν – “nu” or ƒ): number of wavelengths, or cycles, that pass a point per unit time.
Frequency measured in cycles per second (s-1), or the SI unit hertz (Hz)
Amplitude: height of the wave from origin to crest.
Wavelength and frequency do not affect amplitude
Wavelength and frequency are inversely related

4. Composed of radiated waves of both electrical and magnetic energy
Maxwell (1860) - all energy radiated from objects (including visible light) is electromagnetic radiation.
Composed of radiated waves of both electrical and magnetic energy

5. Types of Electromagnetic radiation
Memorize this wavelength range…
f and λ determine what you see or feel, amplitude determines how bright or hot

6. It will always be - ROY G BIV
Sunlight (white light) shone through a prism separates it into a continuous spectrum of colours.
The different wavelength for each colour causes them to refract or bend at different angles
It will always be - ROY G BIV

7. c = λƒ c = λν All EMR radiates at 3.00 x 108 m/s in a vacuum.
This universal value (c) is a product of the wavelength and frequency of the radiated energy.
“speed of light”
c = λƒ
c = λν

8. The colours seen in fireworks are a result of burning different salts
The colours seen in fireworks are a result of burning different salts. Red light has a wavelength of 650 nanometres. Calculate the frequency of red light (1 nm x 10-9 m).
c = λ ƒ ƒ
= x 108 m/s
650 x 10-9 m ƒ
= 4.6 x 1014 Hz

9. Investigated heating objects and
Planck (1900)
Investigated heating objects and
Burning small amounts of each element gave off a unique colour of light
Used to detect a metals presence
Colour
Element
green
copper
yellow
sodium
red
strontium
yellow-green
barium
orange-red
calcium
purple
potassium
purple-red
lithium
Focusing this light through a prism also produces a spectrum, but ONLY distinct lines appear

10. Disclaimer: This is not as simple as my “art” looks
Energy emitted by a element can be separated – to produce a Line spectrum
(emission spectrum)
Disclaimer: This is not as simple as my “art” looks

11. The colored lines of the atoms - Spectral Lines - are a kind of signature (like a finger print) for the atoms.
Spectroscopy and spectrophotometry are techniques used to investigated EMR emissions. C O

12. A photon has no mass but carries a quantum of energy
Planck's Radiation Law:
Energy is transmitted in discrete amounts – called quanta.
EMR is a stream of tiny “packets” of quantized energy carried by particle-like photons.
A photon has no mass but carries a quantum of energy

13. So higher frequency waves contained more energetic “packets”
Energy (quantum) contained in a photon is directly related to the frequency of the radiation.
Eq = hf
E – energy of a quantum (Joules)
h – Plank’s constant (6.626 x J s)
f – frequency of absorbed or emitted EMR
So higher frequency waves contained more energetic “packets”

14. This is the energy per photon
The blue colour of fireworks is often achieved by heating copper (I) chloride to about 1200oC. The wavelength of the blue light is 450 nm. What is the quantum of energy emitted by this light?
ƒ = c λ ƒ
450 x 10-9 m
= x 108 m/s
E = hf ƒ
= 6.7 x 1014 Hz
E = (6.626 x 10-34J· s)(6.7 x 1014 Hz)
E = 4.4 x 10-19J
This is the energy per photon q

15. Compton (1922) – experiment to show particle and wave properties of EMR simultaneously.
Incoming x-rays lost energy and scattered in a way that can be explained with physics of collisions.
Light is both an electromagnetic WAVE, and made of
PARTICLE-like photons of energy

16. C12-2-04 ENERGY AND ATOMIC MODELS
CAN YOU / HAVE YOU?
C ENERGY AND ATOMIC MODELS
Explain average atomic mass using isotopes and their relative abundance.
Include: radioisotopes
Describe the electromagnetic spectrum in terms of frequency, wavelength, and energy.
Include: Plank’s Equation, quantum, photon
Understand the historical development of the Quantum Mechanical Model of the atom.
Describe how unique line spectra are created for each element.
Include: Bohr model
Vocabulary & Concepts
Spectroscopy Emission
Line spectrum