Exam 2 Lecture 4 Flashcards
ΔHf° for an element in it’s standard state
0
Tabulated enthalpies of formation (ΔHf°)
6
What are m and n? 7
8
calculate the enthalpy change for a chemical reaction of interest FORMULA
7
Understanding______ is the key to understanding ______
the arrangement of electrons in atoms, the reactivity of atoms and molecules
Name the superstars of chemical physics
9
Electromagnetic radiation
- • Carries energy
- • Many “types”
- • Moves
- • Wavelike character
Properties of waves
- Regular rise and fall pattern,
- Wavelength (λ, lambda),
- Frequency (ν, nu),
- Amplitude
Regular rise and fall pattern
– Repeating periodicity
– Peak maxima and peak minima 10
Wavelength symbol
(λ, lambda)
Frequency symbol
(ν, nu)
Wavelength definition
the distance from one peak maximum to the next 10
Frequency definition
the number of peak maxima that are passed per unit time 10
Amplitude definition
the height of the peak maxima and minima from the central axis 10
Electromagnetic waves
- Carry energy
- • Electrical and magnetic components
- • Classified based on wavelength
- • Move at a constant speed (c)
- • No propagating medium needed
Frequency is measured in
hertz
a hertz is equal to a
1/second
Directly proportional:
11
• Inversely proportional:
11
What is the difference between AM and FM radio?
AM: Amplitudinal modulation
FM: Frequency modulation
Where is visible light on the electromagnetic spectrum?
133
Where is Infrared on the electromagnetic spectrum?
133
Where is Microwave on the electromagnetic spectrum?
133
Where is radio waves on the electromagnetic spectrum?
133
Where is long radio waves on the electromagnetic spectrum?
133
Where is x rays on the electromagnetic spectrum?
133
Where is uv on the electromagnetic spectrum?
133
Where is gamma rays on the electromagnetic spectrum?
133
What has higher frequency? Gamma rays or Microwaves?
12
What has higher frequency? uv rays or Infrared?
12
Unit for TV/Radio
14
Unit for microwave
14
Unit for infrared
14
Unit for UV
14
unit for X-rays, gamma-rays
14
c
speed of light = 3*10^8 m/s
relationship between light, frequency, and wavelength
15
A high frequency means a
Short wavelength
A low frequency means a
long wavelength
A long wavelength means a
a low freaquency
A short wavelength means a
high frequency
What is the wavelength of 92.1FM?
92.1 Megahertz
Planck: Quantum Effects
• Energy is released/absorbed only in discrete “units”, “packets”, or “quanta”
Quantum definition
the smallest quantity or packet of a given form of electromagnetic radiation
Name some things that are quantized
Energy
Piano music
stairs
Name something not quantized
violin music
