Structure Of The Atom Ch. 2

Question 1

What do atoms consist of?

Answer 1

Protons, Neutrons, Electrons

Question 2

What did John Dalton propose?

Answer 2

The first atomic theory based on experimental evidence.

Question 3

John Dalton’s Conclusions

Answer 3

1. Atoms are small indivisible particles
2. All atoms of a given element are identical to each other
3. Atoms of different elements vary in mass
4. A compound consists of two or more elements combined in fixed proportins

Question 4

Law of conservation of mass

Answer 4

Matter is neither created nor destroyed in the course of a reaction

Question 5

What did William Crookes do?

Answer 5

Used a discharge tube which is a tube with a vacuum and passed invisible rays through it by having a cathode on one end and an anode on the other.

Question 6

What did Crookes observe

Answer 6

With the anode shaped as a cross, a cross shaped shadow was created at the end of the tube

Question 7

What did Crookes call the invisible rays

Answer 7

Cathode rays

Question 8

What did J.J. Thompson show

Answer 8

Showed that cathode rays are attracted to the positive plate, implying that they have a negative charge

Question 9

What did J.J. Thompson conclude

Answer 9

1. Electrons have the same mass to charge ratio no matter which metal they come from
2. Concluded that they are found inside all matter and are 2000 times lighter than an atom of hydrogen

Question 10

What did Johnstone Stoney contribute

Answer 10

He is the person that gave the name electron to the cathode ray

Question 11

What did Johnstone Stoney contribute

Answer 11

He is the person that gave the name electron to the cathode ray

Question 12

What experiment did Robert Millikan conduct

Answer 12

The oil drop experiment

Question 13

What was the purpose of the oil drop experimet

Answer 13

It allows the charge on an election to be measured accurately

Question 14

How does the oil drop experiment work

Answer 14

A voltage is applied to a fine mist of oil drops, the voltage pulls the drops upward and the voltage is adjusted until the drops are suspended.

Question 15

What is the plum pudding model

Answer 15

Created by J.J. Thompson, it is a theory on the makeup of an atom, it shows that an atom is made up of a positive sphere with negative electrons embedded into it.

Question 16

How was the nucleus discovered

Answer 16

Rutherford’s gold foil experiment proved that the atom was made up of mostly empty space, leading him to conclude that the nucleus was small and dense

Question 17

What were the observations from the gold foil experiment

Answer 17

1. A large number of the alpha particles went straight through the foil
2. A small number of the alpha particles were deflected at small angles
3. A very small number were deflected back towards the alpha source at an angle greater than 90°

Question 18

What was the Bohr model of the atom

Answer 18

Proposed that the atom was comprised of a small nucleus with electrons orbiting around it in shells, this model only worked well for hydrogen

Question 19

After repeating his experiment, what did Rutherford find

Answer 19

He found that all elements released the same positively charged particle when bombarded with alpha particles, he concluded that they made up the positive portion of the nucleus