history of the atom worksheet
write the name of the scientist who is credited with the following experiments or discoveries.
1. ______ discovered the electron
2. ______ discovered the nucleus
3. ______ named particles atoms
4. ______ used a cathode ray tube
5. ______ discovered neutrons
6. ______ did the gold foil exp.
7. ______ said all atoms are same for one element
8. ______ plum pudding model

state the subatomic particle that is described in each of the following statements.
9. ______ +1 charge
10. ______ no charge
11. ______
12. ______ found outside nucleus
13. ______ found inside nucleus
14. ______ least massive

answer each of the following questions completely.
15. describe how scientists discovered that atoms were made of electrons (hint: cathode ray tube)

16. how did scientists discover that atoms contained a nucleus?

17. how did scientists discover neutrons?

18. draw a model of how we expect atoms to look. be sure to include the location of subatomic particles.

19. how does the mass of an electron compare to a proton and neutron?

20. put the subatomic particles in order from the most massive to the least massive.

Question

history of the atom worksheet
write the name of the scientist who is credited with the following experiments or discoveries.
1. ______ discovered the electron
2. ______ discovered the nucleus
3. ______ named particles atoms
4. ______ used a cathode ray tube
5. ______ discovered neutrons
6. ______ did the gold foil exp.
7. ______ said all atoms are same for one element
8. ______ plum pudding model

state the subatomic particle that is described in each of the following statements.
9. ______ +1 charge
10. ______ no charge
11. ______
12. ______ found outside nucleus
13. ______ found inside nucleus
14. ______ least massive

answer each of the following questions completely.
15. describe how scientists discovered that atoms were made of electrons (hint: cathode ray tube)

16. how did scientists discover that atoms contained a nucleus?

17. how did scientists discover neutrons?

18. draw a model of how we expect atoms to look. be sure to include the location of subatomic particles.

19. how does the mass of an electron compare to a proton and neutron?

20. put the subatomic particles in order from the most massive to the least massive.

Accepted Answer

### Question 1 - 8 (Matching Scientists to Discoveries)
#### 1. Discovered the electron:
**Explanation**: J.J. Thomson discovered the electron using a cathode ray tube experiment.
**Answer**: J.J. Thomson

#### 2. Discovered the nucleus:
**Explanation**: Ernest Rutherford discovered the nucleus through the Gold Foil Experiment.
**Answer**: Ernest Rutherford

#### 3. Named particles atoms:
**Explanation**: Democritus (ancient Greek philosopher) was among the first to name the tiny particles "atoms" (from the Greek "atomos" meaning indivisible).
**Answer**: Democritus

#### 4. Used a cathode ray tube:
**Explanation**: J.J. Thomson used a cathode ray tube to discover the electron.
**Answer**: J.J. Thomson

#### 5. Discovered neutrons:
**Explanation**: James Chadwick discovered neutrons by bombarding beryllium with alpha particles.
**Answer**: James Chadwick

#### 6. Did the Gold Foil Exp:
**Explanation**: Ernest Rutherford conducted the Gold Foil Experiment, which led to the discovery of the nucleus.
**Answer**: Ernest Rutherford

#### 7. Said all atoms are same for one element:
**Explanation**: John Dalton’s atomic theory stated that all atoms of a given element are identical.
**Answer**: John Dalton

#### 8. Plum pudding model:
**Explanation**: J.J. Thomson proposed the Plum Pudding Model of the atom (electrons embedded in a positive "soup").
**Answer**: J.J. Thomson

### Question 9 - 14 (Subatomic Particles)
#### 9. +1 charge:
**Explanation**: Protons have a +1 (positive) charge.
**Answer**: Proton

#### 10. No Charge:
**Explanation**: Neutrons have no charge (neutral).
**Answer**: Neutron

#### 11. -1 charge:
**Explanation**: Electrons have a -1 (negative) charge.
**Answer**: Electron

#### 12. found outside nucleus:
**Explanation**: Electrons orbit the nucleus in electron clouds (outside the nucleus).
**Answer**: Electron

#### 13. found inside nucleus:
**Explanation**: Protons and neutrons are located inside the atomic nucleus.
**Answer**: Proton, Neutron

#### 14. least massive:
**Explanation**: Electrons have much less mass than protons or neutrons (mass ≈ 1/1836 of a proton).
**Answer**: Electron

### Question 15: How did scientists discover electrons (cathode ray tube)?
**Explanation**:
1. Thomson used a cathode ray tube (a sealed tube with gas, electrodes, and a fluorescent screen).
2. When voltage was applied, a ray (cathode ray) traveled from the negative to positive electrode.
3. The ray was deflected by electric and magnetic fields, showing it carried negative charge.
4. Thomson concluded the ray was made of tiny, negatively charged particles (electrons) that are part of all atoms.

### Question 16: How was the nucleus discovered?
**Explanation**:
1. Rutherford’s Gold Foil Experiment: Alpha particles (positive, heavy) were fired at a thin gold foil.
2. Most particles passed through (atom is mostly empty space), but some were deflected at large angles or bounced back.
3. This suggested a small, dense, positive region (nucleus) in the atom that repelled the alpha particles.

### Question 17: How were neutrons discovered?
**Explanation**:
1. Chadwick bombarded beryllium with alpha particles (from radioactive polonium).
2. This emitted a neutral radiation (neutrons) that could knock protons out of paraffin wax.
3. By measuring the protons’ energy, Chadwick calculated the mass of the neutral particle (neutron), confirming its existence.

### Question 18: Draw the Atom Model
**Explanation**:
- **Nucleus**: At the center, containing protons (positive) and neutrons (neutral, similar mass to protons).
- **Electron Cloud**: Surrounding the nucleus, where electrons (negative, tiny mass) orbit in energy levels (shells).
- Label: Nucleus (protons + neutrons), Electron Cloud (electrons outside nucleus).

### Question 19: Electron Mass vs. Proton/Neutron
**Explanation**:
- Electrons have much less mass than protons or neutrons.
- Mass of electron ≈ $ \frac{1}{1836} $ the mass of a proton (or neutron, which have nearly equal mass).

### Question 20: Order from Most to Least Massive
**Explanation**:
- Neutrons and protons have nearly equal mass (neutron is slightly more massive than proton).
- Electrons are much less massive.
- Order: Neutron > Proton > Electron (or Proton ≈ Neutron, both more massive than Electron).

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QUESTION IMAGE

Question

Explanation:

Question 1 - 8 (Matching Scientists to Discoveries)

1. Discovered the electron:

Answer:

2. Discovered the nucleus: