C1.5 - R* History of the atom

Question 1

Who were the first to have ideas about particles and atoms?

Answer 1

The first to have ideas about:
1. Particles
2. Atoms
were the ancient Greeks

Question 2

The ancient Greeks’ ideas become linked to strong experimental evidence in the 1800s, when what?

Answer 2

The ancient Greeks’ ideas become linked to strong experimental evidence in the 1800s, when John Dalton put forward his ideas about atoms

Question 3

John Dalton’s ideas about atoms in the 1800s:

From his experiments, he suggested what?

Answer 3

From John Dalton’s experiments, he suggested that substances were made up of atoms that were like tiny, hard spheres

Question 4

What were John Dalton’s ideas about chemical reactions in the 1800s?

Answer 4

John Dalton’s ideas about chemical reactions in the 1800s was that the atoms:

1. Rearranged themselves
2. Combined with other atoms in new ways

Question 5

John Dalton’s ideas today are what?

Answer 5

John Dalton’s ideas today are in many ways, still useful

Question 6

What did a scientist called J.J. Thomson discover?

Answer 6

A scientist called J.J. Thomson discovered the electron

Question 7

When did J.J. Thomson discover the electron?

Answer 7

J.J. Thomson discovered the electron at the end of the 1800s, in 1897

Question 8

How did J.J. Thomson discover the electron in 1897

Answer 8

J.J. Thomson discovered the electron in 1897, when he was experimenting by applying high voltages to gases at low pressure

Question 9

J.J. Thomson discovered the electron in 1897, when he was experimenting by applying high voltages to gases at low pressure, because he did experiments on the beams of particles.
What did Thomson find, from the experiments on the beams of particles?

Answer 9

From the experiments on the beams of particles, Thomson found out that they were attracted to a positive charge

Question 10

Why did Dalton’s idea that atoms could not be divided or split had to be revised?

Answer 10

Dalton's idea that atoms could not be:
1. Divided
Or,
2. Split
had to be revised, because these electrons must have come from inside atoms in the tube

Question 11

After Dalton’s idea that atoms could not be divided or split had to be revised, what did Thomson propose?

Answer 11

After Dalton’s idea that atoms could not be:
1. Divided
Or,
2. Split
had to be revised, Thomson proposed a different model for the atom, the plum pudding model

Question 12

After Dalton’s idea that atoms could not be divided or split had to be revised, Thomson proposed a different model for the atom - the plum pudding model.
What did Thomson imagine the electrons as?

Answer 12

Thomson imagined the electrons as the bits of plum in a plum pudding

Question 13

When did the next breakthrough in understanding the atom come, after Thomson’s discovery of electrons?

Answer 13

After Thomson’s discovery of electrons, the next breakthrough in understanding the atom came about 10 years after the new theory for the atomic structure was known as the plum pudding model

Question 14

What were Geiger and Marsden doing?

Answer 14

Geiger and Marsden were:

1. Doing an experiment with radioactive particles
2. Firing dense, positively charged particles (alpha particles) at the thinnest piece of gold foil they could make

Question 15

Geiger and Marsden, in their alpha particle scattering experiments, from the plum pudding model, were expecting what?

Answer 15

Geiger and Marsden, in their alpha particle scattering experiments, from the plum pudding model, were expecting the alpha particles to:
1. Pass straight through the sheet
Or,
2. Be slightly deflected at most

Question 16

What actually happened in Geiger and Marsden’s alpha particle scattering experiments?

Answer 16

In Geiger and Marsden’s alpha particle scattering experiments, whilst most of the particles did go straight through the gold sheet:

1. Some were deflected more than expected
2. A small number were deflected backwards

Question 17

What did Rutherford suggest after Geiger and Marsden’s results for their alpha particle scattering experiments?

Answer 17

After Geiger and Marsden’s results for their alpha particle scattering experiments, Rutherford suggested that Thomson’s atomic model was not possible

Question 18

What is the nuclear model?

Answer 18

The nuclear model is that there is a tiny, positively charged nucleus at the centre, where most of the mass is concentrated

Question 19

How does the nuclear model explain the results of Geiger and Marsden’s alpha particle scattering experiments?

Answer 19

The nuclear model explains the results of Geiger and Marsden’s alpha particle scattering experiments, because:

1. When alpha particles came near the concentrated, positive charge of the nucleus, they were deflected
2. If they were fired directly at the nucleus, they were deflected backwards
3. Otherwise, they passed through the empty space

Question 20

When did the next important development in atomic structure, after electrons and the nucleus come?

Answer 20

After:
1. Electrons
2. The nucleus
,the next important development in atomic structure came in 1914

Question 21

What did Niels Bohr notice when he revised the atomic model again in 1914?

Answer 21

When Niels Bohr revised the atomic model again in 1914, he noticed that the light given out when atoms were heated only had specific amounts of energy

Question 22

What did Niels Bohr suggest after what he noticed when he revised the atomic model again in 1914?

Answer 22

After what he noticed when he revised the atomic model again in 1914, Niels Bohr suggested that the:

1. Electrons must be orbiting the nucleus at set distances, in certain fixed energy levels (or shells)
2. Energy must be given out when excited electrons fall from a high to a low energy level

Question 23

After what he noticed when he revised the atomic model again in 1914, Niels Bohr suggested that the electrons must be orbiting the nucleus at set distances, in certain fixed energy levels (or shells) and the energy must be given out when excited electrons fall from a high to a low energy level.
What did Bohr match his atomic model to?

Answer 23

Bohr matched his atomic model to the energy values observed

Question 24

What did scientists realise about the electrons in Rutherford’s atomic model as he described?

Answer 24

About the electrons in Rutherford’s atomic model as he described, scientists realised that them in a ‘cloud’ around the nucleus of an atom would be attracted to the nucleus

Question 25

What was Bohr's theory of atomic structure supported by?

Answer 25

Bohr's theory of atomic structure was supported by many experiments

Question 26

What did scientists in the early 1900s speculate?

Answer 26

Scientists in the early 1900s speculated that there were 2 types of sub-atomic particles inside the nucleus

Question 27

What did scientists in the early 1900s have?

Answer 27

Scientists in the early 1900s had evidence of protons

Question 28

Scientists in the early 1900s speculated that there were 2 types of sub-atomic particles inside the nucleus. Scientists in the early 1900s had evidence of protons. Why was it very difficult to detect neutrons in experiments?

Answer 28

It was very difficult to detect neutrons in experiments, because they have no charge

Question 29

What did further experimentation after Niels Bohr's theory of atomic structure by Rutherford and other scientists do?

Answer 29

Further experimentation after Niels Bohr's theory of atomic structure by: 1. Rutherford 2. Other scientists gave the conclusion that the nucleus could be divided into smaller particles

Question 30

How were neutrons discovered?

Answer 30

Neutrons were discovered after James Chadwick did an experiment that could only be explained by the existence of neutrons only until 1932

Question 31

What happened about 20 years after scientists had accepted that atoms have nuclei?

Answer 31

About 20 years after scientists had accepted that atoms have nuclei, James Chadwick carried out an experiment which provided evidence for neutral particles in the nucleus

Question 32

What did the discovery of neutrons result in?

Answer 32

The discovery of neutrons resulted in a model of the atom which was pretty close to the modern day accepted version

Question 33

John Dalton's ideas today are in many ways, still useful. | Example

Answer 33

``` For example, they help to visualise: 1. Elements 2. Compounds 3. Molecules As well as the: 4. Models still used to describe the different arrangement and movement of particles in solids, liquids and gases ```

Question 34

From the experiments on the beams of particles, Thomson found out that they were attracted to a positive charge, showing they must be negatively charged themselves. What did he call the tiny, negatively charged particles?

Answer 34

Thomson called the: 1. Tiny 2. Negatively charged particles electrons

Question 35

Geiger and Marsden, in their alpha particle scattering experiments, from the plum pudding model, were expecting the alpha particles to pass straight through the sheet or be slightly deflected at most. Why was this?

Answer 35

This was because the positive charge of each atom was thought to be very spread out through the 'pudding' of the atom

Question 36

After Geiger and Marsden's results for their alpha particle scattering experiments, Rutherford suggested that Thomson's atomic model was not possible. The positive charge must be concentrated at a tiny spot in the centre of the atom, because otherwise, the large, positive particles fired at the foil could never be repelled back towards their source. What did he come up with to explain this new evidence?

Answer 36

Thomson came up with an idea to explain this new evidence, the nuclear model of the atom

Question 37

After what he noticed when he revised the atomic model again in 1914, Niels Bohr suggested that the electrons must be orbiting the nucleus at set distances, in certain fixed energy levels (or shells) and the energy must be given out when excited electrons fall from a high to a low energy level. Bohr matched his atomic model to the energy values observed. What did his nuclear model of the atom suggest?

Answer 37

Thomson's nuclear model of the atom suggested that all the electrons were contained in shells

Question 38

Scientists in the early 1900s had evidence of protons but a 2nd sub-atomic particle in the nucleus was also proposed to explain the missing mass that had been noticed in atoms. What must these neutrons have?

Answer 38

These neutrons must have: 1. No charge 2. The same mass as a proton

Question 39

John Dalton's ideas about atoms in the 1800s: From John Dalton's experiments, he suggested that substances were made up of atoms that were like tiny, hard spheres. He also suggested what?

Answer 39

John Dalton also suggested that each chemical element had its own atoms that differed from others in their mass

Question 40

John Dalton's ideas about atoms in the 1800s: From John Dalton's experiments, he suggested that substances were made up of atoms that were like tiny, hard spheres. John Dalton also suggested that each chemical element had its own atoms that differed from others in their mass. He believed that these atoms could not be what?

Answer 40

John Dalton believed that these atoms could not be: 1. Divided Or, 2. Split

Question 41

John Dalton's ideas about atoms in the 1800s: From John Dalton's experiments, he suggested that substances were made up of atoms that were like tiny, hard spheres. John Dalton also suggested that each chemical element had its own atoms that differed from others in their mass. John Dalton believed that these atoms could not be divided or split. They were the what of nature?

Answer 41

They were the fundamental building blocks of nature

Question 42

A scientist called J.J. Thomson discovered the electron. | The tiny, negatively charged particle was found to have what?

Answer 42

The tiny, negatively charged particle was found to have a mass about 2000 times smaller than the lightest atom

Question 43

J.J. Thomson discovered the electron in 1897, when he was experimenting by applying high voltages to gases at low pressure, because he did what?

Answer 43

J.J. Thomson discovered the electron in 1897, when he was experimenting by applying high voltages to gases at low pressure, because he did experiments on the beams of particles

Question 44

J.J. Thomson discovered the electron in 1897, when he was experimenting by applying high voltages to gases at low pressure, because he did experiments on the beams of particles. From the experiments on the beams of particles, Thomson found out that they were attracted to a positive charge, showing what?

Answer 44

From the experiments on the beams of particles, Thomson found out that they were attracted to a positive charge, showing that they must be negatively charged themselves

Question 45

After Dalton's idea that atoms could not be divided or split had to be revised, Thomson proposed a different model for the atom, the plum pudding model. He said that the tiny negatively charged electrons must be what?

Answer 45

Dalton said that the tiny negatively charged electrons must be embedded in a cloud of positive charge

Question 46

After Dalton's idea that atoms could not be divided or split had to be revised, Thomson proposed a different model for the atom, the plum pudding model. Dalton said that the tiny negatively charged electrons must be embedded in a cloud of positive charge. He knew that atoms themselves carry no overall charge, so any charges in an atom must what?

Answer 46

Dalton knew that atoms themselves carry no overall charge, so any charges in an atom must balance out

Question 47

In Geiger and Marsden's alpha particle scattering experiments, whilst most of the particles did go straight through the gold sheet, some were deflected more than expected and small number were deflected backwards, so what?

Answer 47

In Geiger and Marsden's alpha particle scattering experiments, whilst most of the particles did go straight through the gold sheet: 1. Some were deflected more than expected 2. A small number were deflected backwards ,so the plum pudding model couldn't be right This shocked them

Question 48

In Geiger and Marsden's alpha particle scattering experiments, whilst most of the particles did go straight through the gold sheet: 1. Some were deflected more than expected 2. A small number were deflected backwards ,so the plum pudding model couldn't be right. This what?

Answer 48

This shocked them

Question 49

After Geiger and Marsden's results for their alpha particle scattering experiments, why did Rutherford suggest that Thomson's atomic model was not possible?

Answer 49

After Geiger and Marsden's results for their alpha particle scattering experiments, Rutherford suggested that Thomson's atomic model was not possible, because: 1. The positive charge must be concentrated at a tiny spot in the centre of the atom 2. Otherwise, the large, positive particles fired at the foil could never be repelled back towards their source

Question 50

The nuclear model is that there is a tiny, positively charged nucleus at the centre, where most of the mass is concentrated. What surrounds this nucleus?

Answer 50

A 'cloud' of negative electrons surrounds this nucleus

Question 51

The nuclear model is that there is a tiny, positively charged nucleus at the centre, where most of the mass is concentrated. A 'cloud' of negative electrons surrounds this nucleus, so what?

Answer 51

A 'cloud' of negative electrons surrounds this nucleus, so most of the atom is empty space

Question 52

After electrons and the nucleus, the next important development in atomic structure came in 1914, when what?

Answer 52

After: 1. Electrons 2. The nucleus ,the next important development in atomic structure came in 1914, when Niels Bohr revised the atomic model again

Question 53

Bohr's theory of atomic structure supported by many experiments and it helped to explain what?

Answer 53

Bohr's theory of atomic structure: 1. Supported by many experiments 2. Helped to explain lots of other scientists' observations at the time

Question 54

Scientists in the early 1900s had evidence of protons, but a 2nd sub-atomic particle in the nucleus was also proposed to do what?

Answer 54

Scientists in the early 1900s had evidence of protons, but a 2nd sub-atomic particle in the nucleus was also proposed to explain the missing mass that had been noticed in atoms

Question 55

About the electrons in Rutherford's atomic model as he described, scientists realised that them in a 'cloud' around the nucleus of an atom would be attracted to the nucleus, causing what?

Answer 55

About the electrons in Rutherford's atomic model as he described, scientists realised that them in a 'cloud' around the nucleus of an atom would be attracted to the nucleus, causing the atom to collapse

Question 56

Further experimentation after Niels Bohr's theory of atomic structure by Rutherford and other scientists gave the conclusion that the nucleus could be divided into smaller particles, each of which has what?

Answer 56

Further experimentation after Niels Bohr's theory of atomic structure by: 1. Rutherford 2. Other scientists gave the conclusion that the nucleus could be divided into smaller particles, each of which has the same charge as a hydrogen nucleus

Question 57

About 20 years after scientists had accepted that atoms have nuclei, James Chadwick carried out an experiment which provided evidence for neutral particles in the nucleus. These became known as what?

Answer 57

These neutral particles in the nucleus became known as neutrons

Question 58

The discovery of neutrons resulted in a model of the atom which was pretty close to the modern day accepted version, known as what?

Answer 58

The discovery of neutrons resulted in a model of the atom which was pretty close to the modern day accepted version, known as the nuclear model