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Chemistry: 03 - Arrangement Of Electrons In The Atom > Explaining The Evidence: The Bohr Theory > Flashcards

Explaining The Evidence: The Bohr Theory Flashcards

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1
Q

What did Bohr’s theory introduce the idea of?

A

The idea of quantisation of energy, i.e. that an electron in an atom can only have a fixed amount of energy

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2
Q

What is a quantum of energy?

A

The fixed amount of energy that in an electron in an atom can have

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3
Q

What does quantisation mean?

A

This means that the energy of an electron in an atom cannot have just any value but may only have certain specific values

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4
Q

What is Bohr’s theory often described as providing?

A

As providing spectroscopic evidence for the existence of energy levels.

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5
Q

What did Bohr suggest in relation to the movement of electrons?

A

Electrons revolve around the nucleus in fixed paths called orbits

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6
Q

What are orbits also called?

A

Energy levels

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7
Q

Describe the energy that electrons have in an orbit.

A

Electrons in any one orbit have a fixed amount of energy

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8
Q

What are energy levels represented by?

A

They are represented by the letter n

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9
Q

What is the lowest energy level represented by?

A

n=1

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10
Q

What is the next energy above from n=1 represented by?

A

n=2

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11
Q

Describe the energy of the electron in a particular energy level.
(2)

A

The energy in a particular orbit or energy level is quantised, i.e. fixed at a definite value

An electron will have a certain amount of energy depending on the orbit or energy level in which it is located

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12
Q

Define an energy level.

A

An energy level is defined as the fixed energy value that an electron in an atom may have

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13
Q

How did Bohr explain why electrons do not lose energy and fall into the nucleus?

A

He stated that as long as an electron is in any one particular energy level, it neither gains nor loses energy

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14
Q

Under what condition will an electron neither gain nor lose energy?

A

As long as an electron is in any one particular energy level

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15
Q

At what state do atoms normally exist?

A

They normally exist in the ground state

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16
Q

Define the ground state.

A

The ground state of an atom is one in which the electrons occupy the lowest available energy levels

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17
Q

Describe the energy an electron has when the atom in the ground state.

A

Electrons in the ground state have energy of fixed values, i.e. the energy of the electrons in a particular orbit or energy level is fixed or quantised

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18
Q

Describe the energy electrons occupy in the ground state.

A

In the ground state the electrons occupy the lowest available energy levels

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19
Q

What happens when an atom in the ground state is provided with energy?

A

A specific amount of this energy is absorbed and the electrons jump from lower energy levels to higher energy levels - electrons are now in the excited state

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20
Q

Define the excited state.

A

The excited state of an atom is one in which the electrons occupy higher energy levels than those available in the ground state

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21
Q

How does an atom enter the excited state?

A

When an atom in the ground state is provided with energy

22
Q

Describe the absorbed energy when an electron becomes excited.

A

The energy absorbed is equal to the difference in energy between the ground state/lower energy level and an excited state/a higher energy level

23
Q

Describe the electrons in the excited state?

A

They are unstable and they fall back down to lower energy levels after a short period of time

24
Q

What happens as an electron falls back to a lower energy level from its excited state?

A

Energy is released in the form of a photon of light which has a definite amount of energy i.e. light of a definite frequency is given off

25
Q

What does the frequency of the light emitted depend on?

A

The difference in energy between the two energy levels

26
Q

Give the equation for the frequency of light.

A

E2 - E1 = hf

27
Q

What does h = in the following equation?

E2 - E1 = hf

A

Planck’s constant

28
Q

What does f = in the following equation?

E2 - E1 = hf

A

Frequency of light emitted

29
Q

What does E2 = in the following equation?

E2 - E1 = hf

A

Energy of higher energy level

30
Q

What does E1 = in the following equation?

E2 - E1 = hf

A

Energy of lower energy level

31
Q

What does E2 - E1 = hf tell us?

A

It tells us that the energy difference is proportional to the frequency of the light emitted

32
Q

What does the definite amount of energy emitted appear as?

A

It appears as a line of a particular colour

33
Q

When a definite amount of energy is emitted when an electron falls from one energy level to another it appears as a line of a particular colour, what does this form?

A

This forms an emission line spectrum

34
Q

What piece of evidence implies that electrons can occupy only definite energy levels?

A

Since only definite amounts of energy are emitted

35
Q

Only definite amounts of energy are emitted when an electron falls from its excited state to its ground state, what does this indicate?

A

this implies that definite amounts of energy are emitted

36
Q

Each definite amount of energy emitted gives rise to what?

A

A line in the emission spectrum

37
Q

Summarise Bohr’s Theory (the general points only)

5

A

Electrons revolve around the nucleus in fixed paths called orbits

Electrons in any one orbit have a fixed amount of energy

Energy levels are represented by the letter n

The energy of the electron in a particular orbit or energy is quantised

As long as an electron is in any one particular energy level, it neither gains nor loses energy

38
Q

Summarise Bohr’s Theory (the points on the ground state)

4

A

Atoms normally exist in the ground state

Electrons in the ground state have energy of fixed values

In the ground state the electrons occupy the lowest available energy levels

When an atom in its ground state is provided with energy a specific amount of this energy is absorbed and the electrons jump from lower energy levels to higher energy levels - excited state

39
Q

Summarise Bohr’s Theory (the points on the excited state)

4

A

The energy absorbed is equal to the difference in energy between the lower energy level and a higher energy level

Electrons in the excited state are unstable and they fall back down to lower energy levels after a short period of time

As an electron falls back to a lower energy level, the excess energy is released in the form of a photon of light which has a definite amount of energy

The frequency of the light emitted depends on the difference in energy between the two energy levels

40
Q

Summarise Bohr’s Theory (the points on the line spectra)

5

A

The energy difference is proportional to the frequency of the light emitted

The definite amount of energy emitted appears as a line of particular colour

Since only definite amounts of energy are emitted, this implies that electrons can occupy only definite energy levels

Each definite amount of energy emitted gives rise to a line in the emission spectrum

Each element has a unique emission line spectrum

41
Q

What are the names of the two invisible series of transitions?

A

Paschen series

Lyman series

42
Q

What is the name of the visible series of transitions?

A

Balmer series

43
Q

What transitions are involved in the Paschen series?

A

All transitions between that fall to n=3

E,g. 5 to 3, 4 to 3, or higher 6 to 3, 7 to 3

44
Q

What transitions are involved in the Lyman series

A

All transitions that fall to n=1

e.g. n=5 to n=1, n=3 to n=1 etc

45
Q

What transitions are involved in the Balmer series?

A

All transitions that fall to n=2

e.g. n=3 to n=2 or n=5 to n=2

46
Q

Where is the Paschen series found?

A

It is found in infrared region

47
Q

Where is the Lyman series found?

A

In the ultraviolet region

48
Q

Which series is found in the infrared region?

A

Paschen series

49
Q

Which series is found in the Lyman series?

A

Lyman series

50
Q

What series are the transitions to n=3 called?

A

Paschen series/ infrared series

51
Q

What series are the transitions to n=2 called?

A

Balmer series

52
Q

What series are the transitions to n= 1 called?

A

Lyman series

Chemistry: 03 - Arrangement Of Electrons In The Atom (10 decks)

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