Chapter 4: Atoms and Light

Question 1

What are the 6 characteristics of atoms?

Answer 1

1.Possess mass
2. Contain positive nuclei
3. Contain electrons
4. Occupy volume
5. Attract one another
6. Combine to form molecules

Question 2

The best tool for studying the structure of atoms is?

Answer 2

Electromagnetic radiation

Question 3

Wavelength (y)

Answer 3

The distance between two successive crests

Question 4

Frequency (v)

Answer 4

The number of waves passing a certain point over a unit of time

Question 5

Amplitude

Answer 5

The height of the wave measured from the axis of propagation, a measure of intensity

Question 6

What is the photoelectric effect?

Answer 6

Below a threshold frequency, no electrons are observed, regardless the intensity of light

Above the threshold frequency, the number of emitted electrons increases with the intensity of the light

All metals show the same pattern, but each metal has a different threshold frequency

Question 7

What are the two properties of light?

Answer 7

1. Wave-like
2. Particle-like

Question 8

What are photons?

Answer 8

Packets of energy

Question 9

Electrons are only ejected if…

Answer 9

The frequency of light is high enough

Question 10

Is the ejection of electrons dependent on the intensity of light?

Answer 10

No

The greater the intensity, the more photons but if no photon has enough energy to remove an electron, none will be ejected

Question 11

What is photoionization?

Answer 11

The ejection of an electron

Question 12

What is an excited state?

Answer 12

When an atom absorbs a photon

Question 13

What is the ground state?

Answer 13

Lowest energy state of an atom

Question 14

What is absorption spectrum?

Answer 14

Measures the frequencies of photons that an atom absorbs

Very colourful. The dark bands = light absorbed by the sample

Question 15

What is an emission spectrum?

Answer 15

The intensity of light as a function of frequency
Dark. The colour represents the photons emmited

Question 16

What did Niels Bohr discover?

Answer 16

That electrons can only occupy certain energy levels

Question 17

What are the 3 properties of electrons?

Answer 17

1. Each electron has the same mass and charge
2. Electrons behave like magnets
3. Electrons have wave properties

Question 18

What is Heisenberg’s Uncertainty Principle?

Answer 18

The more accurately we know an electrons position, the more uncertain we are about motion, and vice versa

We identify a “probable location” of the electrons in an atom

Question 19

What does the Principle Quantum Number represent? (n)

Answer 19

The quantized energy of an atomic electron

Corresponds to an electron “shell”

Question 19

What does the Azimuthal Quantum Number (l) represent?

Answer 19

The shapes of atomic orbitals
n-1

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

Question 20

What does the Magnetic Quantum Number represent? (ml)

Answer 20

The different orientations of the orbitals
-l-+l

Question 21

What does the Spin Orientation Quantum Number represent? (ms)

Answer 21

The direction
Magnetism is directional so, ms= +1/2 or -1/2

Question 22

What do orbitals describe?

Answer 22

The delocalization of electrons

Question 23

Each orbital becomes _____ as nuclear charge increases

Answer 23

Smaller

Question 24

In any atom, are orbitals with the same principle quantum number similar sizes?

Answer 24

Yes

Question 25

What shape are all s orbitals?

Answer 25

Spherical

Question 26

How many possible p-orbitals are there?

Answer 26

3

Question 27

How many possible d-orbitals are there?

Answer 27

5

Question 28

How many possible f-orbitals are there?

Answer 28

7

Question 28

How does ozone protect the earth from harmful radiation?

Answer 28

It absorbs UV light

Question 29

What is the greenhouse gas effect?

Answer 29

CO2 absorbs and remits infra-red radiation, which overtime, increases the earth’s average temperature