Lesson 4.3

Question 1

is discovered using a cathode-ray tube

Answer 1

Electron

Question 2

the cathode-ray tube has two charged plates

Answer 2

cathode and anode

Question 3

an English physicist used the cathode ray tube, and the electromagnetic theory to determine the ratio of electric charge to the mass of the individual negatively charged particle

Answer 3

Joseph John Thomson ( also known as J.J. Thomson)

Question 4

Some experiments added two electrically charged plates and a magnet to the outside of the cathode ray tube.

Question 5

ratio of electric charge to the mass of the individual negatively charged particle

Question 6

If the magnetic field is on and the electric field is off, the cathode ray hit point A.(_)

Answer 6

Upper

Question 7

If only the electric field is on, the ray hit point C.(_)

Answer 7

Lower

Question 8

If both the magnetic and the electric fields are off or when they cancel each other’s influence, the ray strikes point B.(_)

Answer 8

Straight middle

Question 9

Since the cathode ray is attracted to the positively-charged plate and repelled by the negatively-charged plate, it must consist of negatively-charged particles.

This negatively charged particle was called _.

Answer 9

electron

Question 10

The mass to charge ratio obtained by Sir J.J. Thomson was

Answer 10

1.76 ✕ 10^8 C/g

Question 11

1.76 ✕ 108 C/g, where C stands for _, the unit of the electrical charge.

Answer 11

coulomb

Question 12

was able to quantify the charge of the electron in his oil-drop experiment in 1906.

Answer 12

Robert Millikan

Question 13

In Millikan’s experiment, he used a fine spray of ionized oil.

With electromagnetic force, the droplets suspended in air.

He was able to calculate the charge of the electron and the mass of the electron

The charge of the electron = _

Answer 13

–1.6022 ✕ 10^-19 C

Question 14

In Millikan’s experiment, he used a fine spray of ionized oil.

With electromagnetic force, the droplets suspended in air.

He was able to calculate the charge of the electron and the mass of the electron

The mass of the electron = _

Answer 14

9.10 ✕ 10^-28 g

Question 15

During the early 1900s, two features of atoms had become clear.

Atoms contain electrons.

Atoms are electrically neutral.

In order to maintain an electrical neutral atom. It must contain an equal number of positive and negative charges.

Answer 15

The Plum Pudding Model

Question 16

In 1910, a New Zealand physicist _ _ decided to use alpha particles to probe the structure of the atoms, together with his associate Hans Geiger and an undergraduate named Ernest Maden.

Answer 16

Ernest Rutherford

Question 17

They observed that the majority of particles penetrated the foil either undeflected or slightly deflected.

Some alpha particles were deflected at a large angle. In some instances, an alpha particle bounced back in the direction of its source.

Question 18

Most of an atom must be empty space with electrons that allow the majority of the alpha particle to pass through.

On the center of the atom, there is a positively charged dense core (_).

Answer 18

Nucleus

Question 19

The positively charged particles in the nucleus are called

Answer 19

Proton

Question 20

In separate experiments, the charge of each proton has the same magnitude as that of electron

Answer 20

–1.6022 ✕ 10^-19 C

Question 21

In separate experiments, the charge of each proton has the same magnitude as that of electron and that the mass of the proton is _

Answer 21

1.67262 ✕ 10 -24 grams.

Question 22

The inconsistency on the ratio of the mass hydrogen atom to the mass of helium atoms led Rutherford and the other scientists to speculate that there must be another subatomic particle in the atomic nucleus.

The proof was provided by another English physicist, _ _, in 1932 on his alpha particle and beryllium experiment.

Answer 22

James Chadwick

Question 23

Later experiments revealed that the rays consisted of electrically neutral particles having a mass slightly greater than that of protons.

Chadwick names these particles, as _

Answer 23

Neutrons

Question 24

An atom has an electron, proton, and neutron. Protons and neutrons are packed in an extremely small nucleus and carries the bulk of the mass of an atom, while the electrons occupy the space around the nucleus providing volume to the atom.

Question 25

proposed that the electron move in orbits around the nucleus

Planetary Model

Answer 25

Neils Bohr

Question 26

proposed that electrons do not move in a set of paths around the nucleus but in waves

impossible to locate electrons, cloud of probability

Electron Cloud Model

Question 27

The three subatomic particles of an atom are electron, proton, and neutron.

The electron was discovered by J.J. Thomson using a cathode ray experiment, while Robert Millikan calculated the charge and mass of the electron through his oil-drop experiment.

The nucleus and proton was discovered by Ernest Rutherford and his associates through the gold foil experiment.

The neutron was discovered by James Chadwick through his alpha particle and beryllium experiment.