History of Atomic Theory

Question 1

Order of Rutherford, Dalton, Thomson

Answer 1

1. Dalton
2. Thomson
3. Rutherford

Question 2

Dalton’s discovery

Answer 2

Atomic Theory

Question 3

3 Main points of Atomic Theory (Dalton)

Answer 3

1. Each element is made of tiny indestructible particles called atoms
2. All atoms of a given element have the same properties
3. Atoms combine in simple, whole-number ratios to form compounds

Question 4

What did Dalton say about formation of atoms

Answer 4

Atoms cannot be subdivided, created, or destroyed

Question 5

Out of main 3 what number was Dalton

Answer 5

1

Question 6

Out of main 3 what number was Rutherford

Answer 6

3

Question 7

Out of main 3 what number was Thomson

Answer 7

2

Question 8

What did Thomson discover

Answer 8

The electron

Question 9

3 Main points of electron discovery (Thomson)

Answer 9

1. Electrons are negatively charged
2. Electrons are smaller and lighter than atoms
3. Electrons are uniformly present in may different kinds of substances

Question 10

Plum Pudding experiment

Answer 10

Plum pudding is pudding mixed with fruits

Thomson thought the pudding was a “sphere of positive charge” and the fruits were the electrons

Question 11

What inspired Plum Pudding experiment

Answer 11

It was known that atoms were charge-neutral so if they had negative charges (electrons) in them they had to have positive charges too

Question 12

Cathode Ray Tube expirement

Answer 12

The set up was a vacuum-sealed glass tube, on one side there was a cathode (a negatively charged conductor) and anode (a positively charged conductor).
The electrons were attracted to the anode (because they have a negative charge) and there is a small hole in the anode so some of the electrons passed through - creating a beam of electrons.
On the other side of the tube there was a coating that glowed when struck with electrons.
This gave Thomson a chance to see where the electron beam was hitting.

Question 13

How did Thomson discover the electron

Answer 13

Cathode Ray Tube experiment

Question 14

What subatomic particle did Thomson discover

Answer 14

The electron

Question 15

Which experiment disproved the Plum Pudding experiment

Answer 15

Rutherford’s Gold Foil experiment

Question 16

What Gold Foil experiment proved

Answer 16

There was a small massive center to an atom

Later found out to be a nucleus

Question 17

What theory did Rutherford create because of Gold Foil experiment

Answer 17

Nuclear Theory of the Atom

Question 18

3 Main points of Nuclear Theory of the Atom (Rutherford)

Answer 18

1. Most of an atom’s mass and positive charge are found in nucleus
2. Most of the volume of atom is empty space, where electrons are dispersed
3. There are the same amount of negatively charged electrons outside of nucleus as there are protons

Question 19

What did Mendeleev discover

Answer 19

The Periodic Law

Question 20

How did Mendeleev reach his law

Answer 20

He listed the periodic table elements in increasing mass and noticed a recurring pattern of properties
A predictable rewriting pattern