Chapter 07: The Quantum-Mechanical Model of the Atom Flashcards Preview

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Flashcards in Chapter 07: The Quantum-Mechanical Model of the Atom Deck (45)
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1
Q

Light

A

A form of electromagnetic radiation

Composed of perpendicular oscillating waves
(one = electric field, other = magnetic field)

2
Q

Electric field

A

A region where an electrically charged particle experiences a force

3
Q

Magnetic field

A

A region where a magnetized perticle experiences a force

4
Q

Speed of light

A

c

c = 3.00 × 108 m/s

5
Q

Wavelength

A

λ (lambda)

The distance between identical points on successive waves

*Inversely proportional to frequency

6
Q

Amplitude

A

The verticle distance from the midline of a wave to the peak (or trough)

A measure of light intensity

*Directly proportional to total energy of wave
(larger amplitude = more force)

7
Q

Frequency

A

v (nu)

v = c / λ

The number of waves that pass through a particular point in a given period of time

hertz (Hz) or cycles per second (1 s-1)

1 Hz = 1 s-1

*Directly proportional to total energy of a wave
(More frequency = more total force)

*Inversely proportional to wavelenth

8
Q

Electromagnetic spectrum

A

Low energy to high:

radio
microwave
infared
visible light
ultraviolet
X-ray
gamma ray

9
Q

Interference

A

The interaction between waves

10
Q

Constructive interference

A

Occurs when waves that are in phase interact so that they add to make a larger wave

*Amplitudes are summed making the larger wave

11
Q

Destructive interference

A

Occurs when waves that are out of phase interact so that they cancel each other out (flat line)

12
Q

Diffraction

A

Occurs when a traveling wave encounters an obstacle or opening in a barrier that is about the same size as its wavelengh and it bends (diffracts) around it

*Waves diffract

**Particles DO NOT diffract (they just pass through opening)

13
Q

Interference pattern

A

Inherent characteristic of all waves

Light is diffracted through two slits creating an alternating pattern

14
Q

Photoelectric effect

A

The observation that many metals emit electrons when light shines on their surface

15
Q

Quanta or photons

A

Light energy delivered to atoms in "packets"

16
Q

Photon energy

A

E

E = hv 

v = c/λ

Thus:

E = hc/λ

17
Q

Planck's constant

A

h

h = 6.626 × 10-34 J×s

18
Q

Threshold frequency

A

Reached when the energy of a photon is equal to the binding energy of emitted electron

hv = Φ

or E = Φ

19
Q

Binding energy of emitted electron

A

Φ (phi)

20
Q

Kinetic energy of an ejected electron

A

KE = hv - Φ

Excess energy of a photon that is transferred to an electron in the form of kinetic energy

21
Q

Wave-particle duality of light

A

Sometimes light appears to behave like a wave, other times like a particle

Behavior observed depends on experiment

22
Q

Number of photons

A

Number of photons = Epulse / Ephoton

*Ephoton = hc/λ

23
Q

Atomic spectroscopy

A

The study of the electromagnetic radiation absorbed and emitted by atoms

24
Q

Emission spectrum

A

The "fingerprint" of an element in the form of a series of bright lines

Can be used to identify an element

25
Q

Bohr model of the atom (4)

A

1. Energy of atom is quantized (can only have very specific amounts of energy

2. Amount of energy in atom relates to electron's position in atom

3. Electrons travel in orbits/fixed distance from nucleus
*Energy of electron proportional to distance

4. Electrons emit radiation when they "jump" from an orbit with higher energy down to lower energy orbit
*Distance determins energy of photon of light produced

26
Q

de Broglie relation

A

Wavelength inversely proportional to momentum (mv)

λ = h/mv

(Wavelength = h/mass * frequency)

27
Q

Complimentary properties

A

The more you know about one property, the less you know about the other

When wave nature (interference pattern) is observed, particle nature (position/which slit electron passes through) cannot be, and vice versa

28
Q

Heisenberg uncertainty principle

A

Product of uncertainties in both position and speed of a particle is inversely proportional to its mass

Δx × mΔv ≥ h/4π

Δx = position uncertainty

Δv = velocity uncertainty

m = mass

29
Q

Indeterminacy

A

Indefinite future = can only predict probability

30
Q

Orbital

A

A probability distribution map of a region where the electron is likely to be found

31
Q

Quantum numbers (4)

A

1. Principal quantum number, n

2. Angular momentum quantum number, l

3. Magnetic quantum number, ml

4. Spin quantum number, ms

32
Q

Principal quantum number

A

n

Indicates the orbital (Bohr's energy level)

*As n gets larger, amount of energy between orbitals gets smaller

33
Q

Equation for energy of a hydrogen electron

A

En = -RH (1/n2)

RH is Rydberg constant for hydrogen
RH = 2.18 × 10-18 J

34
Q

Angular momentum quantum number

A

l

Angular momentum = what kind of/angle of orbit

l = 0, 1,... n-1

l = 0 → s
l = 1 → p
l = 2 → d
l = 3 → f

e.g.
n = 2
l = [0, 1]

35
Q

Magnetic quantum number

A

ml

ml = [-l, l]

e.g.
n = 2
l = [0, 2] → d orbital
ml = [-2, 2] → 5 d orbitals

36
Q

Spin quantum number

A

ms

Specifies the orientation of the spin of the electron

Value is either:
+1/2 (spins up)
or
-1/2 (spins down)

37
Q

Describing an orbital (3)

A

1. n, l, ml describes one orbital
2. Orbitals with same n value = same principal energy level (shell)
3. Orbitals with the same values of n & l = same sublevel (subshell)

38
Q

Equation for energy transition in hydrogen

A

ΔE = Efinal - Einitial

ΔEH atom = -2.18 × 10-18 J (1/n2final - 1/n2initial)

Energy emitted by electron is carried away by the releated photon, thus:

Ephoton = -ΔE

39
Q

Probability density

A

The probability of finding an electron at a particular point in space

Probability decreases as distance from nucleus increases

40
Q

Radial distribution function

A

Total probability of finding an electron at a certain distance r from the nucleus

Volume of shell also increases with distance from nucleus

41
Q

Nodes

A

Where the probability drops to zero, for both probabilities

42
Q

s orbital

A

l = 0

spherical shape

1 s orbital

43
Q

p orbital

A

l = 1

shaped like two balloons

-1, 0, 1

3 p orbitals

44
Q

d orbital

A

l = 2

shaped like four balloons

-2, -1, 0, 1, 2

5 d orbitals

45
Q

f orbital

A

l = 3

shaped like eight balloons

-3, -2, -1, 0, 1, 2, 3

7 f orbitals