Q: Which of the following equations represents the charge-to-mass ratio of the electron as determined by J.J. Thomson?

$$\frac{e}{m} = -1.76 \times 10^8$ \ \mathrm{C/g}$$

Question 1

Which experimental tool allowed scientists to directly observe individual atoms for the first time, as shown in the first image?

Accepted Answer

A scanning tunnelling microscope (STM)

Question 2

The second image shows a cathode ray tube. What key discovery did J.J. Thomson make using this apparatus?

Accepted Answer

The existence of the electron

Question 3

Which model of the atom is represented by the fourth image (the muffin with embedded blueberries)?

Accepted Answer

Thomson's 'blueberry muffin' model

Question 4

The fifth image depicts an experiment involving oil droplets and charged plates. What fundamental property of the electron was determined using this experiment?

Accepted Answer

The charge of the electron

Question 5

Which of the following statements best explains why most alpha particles passed straight through the gold foil in Rutherford's experiment (related to the seventh image)?

Accepted Answer

Atoms are mostly empty space

Question 6

If the nucleus of an atom were the size of a ball bearing, as shown in the eighth image, how large would the atom be in comparison?

Accepted Answer

The size of a sports stadium

Question 7

Which experiment provided evidence that atoms contain a small, dense, positively charged nucleus?

Accepted Answer

Rutherford's gold foil experiment

Question 8

Which subatomic particle is responsible for the chemical properties of an element?

Accepted Answer

Electron

Question 9

Which of the following best describes an isotope?

Accepted Answer

Atoms with the same number of protons but different numbers of neutrons

Question 10

Which equation did Max Planck propose to describe the quantization of energy?

Accepted Answer

$$E = nhf$$

Question 11

According to quantum theory, what is a photon?

Accepted Answer

A unit of light energy

Question 12

Which property of light could NOT be explained by classical wave theory, but was explained by quantum theory?

Accepted Answer

The photoelectric effect

Question 13

Which of the following is true about radioisotopes?

Accepted Answer

They emit radiation due to unstable nuclei

Question 14

Which scientist explained the photoelectric effect by proposing that light consists of quanta (photons)?

Accepted Answer

Albert Einstein

Question 15

Which of the following best describes the relationship between the atomic number ($$Z) $$and the mass number ($$A) of an $$atom?

Accepted Answer

$$Z is $$the number of protons; $$A is $$the total number of protons and neutrons

Question 16

Which of the following equations represents the charge-to-mass ratio of the electron as determined by J.J. Thomson?

Accepted Answer

$$\frac{e}{m} = -1.76 	imes 10^8$ \ \mathrm{C/g}$$

Question 17

Which type of radioactive emission has the highest penetrating power?

Accepted Answer

Gamma rays

Question 18

A neutral atom of iron-56 ($$^{56}_{26}\mathrm{Fe}) $$contains how many protons, neutrons, and electrons?

Accepted Answer

26 protons, 30 neutrons, 26 electrons

Question 19

Which real-world application uses the radioactive isotope carbon-14?

Accepted Answer

Archaeological dating

Question 20

Which of the following best explains why the mass of the nucleus is not simply the sum of the masses of the protons?

Accepted Answer

The nucleus also contains neutrons

Lesson 3.1: Early Atomic Theories and the Origins of Quantum Theory

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