P1.1 History Of Atom + Atomic structure

Question 1

Series of scientists in history of atom

Answer 1

Dalton, JJ Thomson, Ernest Rutherford (Hans Geiger + Ernest Marsden), Niels Bohr

Question 2

What did Dalton believe

Answer 2

Very small indestructible sphere.
All atoms in an element are the same
Atoms in one element are different from atoms in all other elements

Question 3

What did JJ Thompson discover

Answer 3

Electron inside the atom (negative charge) he then made sense that:
An atom contains negative electrons
Overall atoms have neutral charge
Positive mass with negative electrons embedded

Question 4

What was JJ thomsons model

Answer 4

Plum pudding model

Question 5

Which 2 scientists did Ernest rutherford work with

Answer 5

Hans Geiger and Ernest Mardsen

Question 6

What was Rutherfords experiment

Answer 6

Fired alpha particles (+ charge) at thin gold sheet of foil. Particles were expected to pass straight through the gold sheet or only slightly deflect. Most particles did go straight through, but some deflected more than expected

Question 7

What did Rutherford learn from his experiment?

Answer 7

Tiny positive charged nucleus at centre
Surrounded by a cloud of negative electrons
Most of atom is empty space

Question 8

What was a problem with the nuclear atom?

Answer 8

Electrons in a cloud around the positively charged nucleus would be attracted to it, causing the atom to collapse

Question 9

What was Neil Bohr’s model of the atom?

Answer 9

Electrons can only move in fixed orbits called electron shells around the nucleus. Each shell has a fixed energy.

Question 10

Nuclear radius ?

Answer 10

1 x 10^-15m

Question 11

Mass of atom

Answer 11

1 x 10^-23

Question 12

Where is most of the mass in an atom?

Answer 12

In the nucleus. The rest of the atom is mostly empty space

Question 13

What gives the atom its overall size?

Answer 13

Electron shells that move around the nucleus really quickly

Question 14

Diameter of an atom

Answer 14

1 x 10^-10m

Question 15

nuclear radius vs atomic radius

Answer 15

Nuclear radius is around 10,000 times smaller than the atomic radius.

Question 16

What is the relative mass and charge of a proton

Answer 16

Mass: 1
Charge: +1

Question 17

What is the relative mass and charge of a neutron?

Answer 17

Mass: 1
Charge: 0

Question 18

What is the relative mass and charge of an electron

Answer 18

Mass: 0.0005
Charge: -1

Question 19

Why is the plum pudding model no longer an acceptable model?

Answer 19

It doesn’t represent all the subatomic particles of an atom and incorporates the electrons into the centre of the atom whereas they should be orbiting in fixed shells around the atom.

Question 20

Estimate number of atoms in a molecule that is 2 x 10-9m long

Answer 20

20??

Question 21

Why did scientists take many years to accept Dalton’s ideas about atoms?

Answer 21

Because atoms could not be seen so dalton could not base his theory on direct observation.