Chapter 07: The Quantum-Mechanical Model of the Atom

Question 1

Light

Answer 1

A form of electromagnetic radiation

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

Question 2

Electric field

Answer 2

A region where an electrically charged particle experiences a force

Question 3

Magnetic field

Answer 3

A region where a magnetized perticle experiences a force

Question 4

Speed of light

Answer 4

c

c = 3.00 × 10⁸ m/s

Question 5

Wavelength

Answer 5

λ (lambda)

The distance between identical points on successive waves

*Inversely proportional to frequency

Question 6

Amplitude

Answer 6

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)

Question 7

Frequency

Answer 7

• 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

Question 8

Electromagnetic spectrum

Answer 8

Low energy to high:

radio
microwave
infared
visible light
ultraviolet
X-ray
gamma ray

Question 9

Interference

Answer 9

The interaction between waves

Question 10

Constructive interference

Answer 10

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

*Amplitudes are summed making the larger wave

Question 11

Destructive interference

Answer 11

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

Question 12

Diffraction

Answer 12

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)

Question 13

Interference pattern

Answer 13

Inherent characteristic of all waves

Light is diffracted through two slits creating an alternating pattern

Question 14

Photoelectric effect

Answer 14

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

Question 15

Quanta or photons

Answer 15

Light energy delivered to atoms in “packets”

Question 16

Photon energy

Answer 16

E

E = hv

v = c/λ

Thus:

E = hc/λ

Question 17

Planck’s constant

Answer 17

h

h = 6.626 × 10^-34 J×s

Question 18

Threshold frequency

Answer 18

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

hv = Φ

or E = Φ

Question 19

Binding energy of emitted electron

Answer 19

Φ (phi)

Question 20

Kinetic energy of an ejected electron

Answer 20

KE = hv - Φ

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

Question 21

Wave-particle duality of light

Answer 21

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

Behavior observed depends on experiment

Question 22

Number of photons

Answer 22

Number of photons = E_pulse / E_photon

*E_photon = hc/λ

Question 23

Atomic spectroscopy

Answer 23

The study of the electromagnetic radiation absorbed and emitted by atoms

Question 24

Emission spectrum

Answer 24

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

Can be used to identify an element

Question 25

Bohr model of the atom (4)

Answer 25

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

Question 26

de Broglie relation

Answer 26

Wavelength inversely proportional to momentum (m*v*) λ = h/m*v* (Wavelength = h/mass \* frequency)

Question 27

Complimentary properties

Answer 27

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

Question 28

Heisenberg uncertainty principle

Answer 28

Product of uncertainties in both position and speed of a particle is inversely proportional to its mass Δx × mΔ*v* ≥ h/4π Δx = position uncertainty Δ*v* = velocity uncertainty m = mass

Question 29

Indeterminacy

Answer 29

Indefinite future = can only predict **probability**

Question 30

Orbital

Answer 30

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

Question 31

Quantum numbers (4)

Answer 31

1. Principal quantum number, n 2. Angular momentum quantum number, l 3. Magnetic quantum number, m_l 4. Spin quantum number, m_s

Question 32

Principal quantum number

Answer 32

n Indicates the orbital (Bohr's energy level) \*As n gets larger, amount of energy between orbitals gets smaller

Question 33

Equation for energy of a hydrogen electron

Answer 33

**E_n = -R_H (1/n²)** R_H is Rydberg constant for hydrogen R_H = 2.18 × 10^-18 J

Question 34

Angular momentum quantum number

Answer 34

l Angu**l**ar 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]

Question 35

Magnetic quantum number

Answer 35

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

Question 36

Spin quantum number

Answer 36

**m_s** Specifies the orientation of the spin of the electron Value is either: +1/2 (spins up) or -1/2 (spins down)

Question 37

Describing an orbital (3)

Answer 37

1. n, l, m_l 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)

Question 38

Equation for energy transition in hydrogen

Answer 38

ΔE = E_final - E_initial **ΔE_{H atom} = -2.18 × 10^-18 J (1/n²_final - 1/n²_initial)** Energy emitted by electron is carried away by the releated photon, thus: **E_photon = -ΔE**

Question 39

Probability density

Answer 39

The probability of finding an electron at a **particular** **point** in space Probability decreases as distance from nucleus increases

Question 40

Radial distribution function

Answer 40

**Total probability** of finding an electron at a **certain** **distance** *r* from the nucleus Volume of shell also increases with distance from nucleus

Question 41

Nodes

Answer 41

Where the probability drops to zero, for both probabilities

Question 42

s orbital

Answer 42

l = 0 spherical shape 1 s orbital

Question 43

p orbital

Answer 43

l = 1 shaped like two balloons -1, 0, 1 3 p orbitals

Question 44

d orbital

Answer 44

l = 2 shaped like four balloons -2, -1, 0, 1, 2 5 d orbitals

Question 45

f orbital

Answer 45

l = 3 shaped like eight balloons -3, -2, -1, 0, 1, 2, 3 7 f orbitals