History Of The Atom

Question 1

What did John Dalton do?

Answer 1

Atoms were first described as solid spheres but there are different

(Discovery of elements)

Question 2

What did JJ Thomson do?

Answer 2

Plum Pudding Model. That the atom is a ball of charge with electrons embedded in them

Question 3

What did Ernest Rutherfod discover?

Answer 3

The most mass is at the center of the atom most of it is empty space as most of the atoms passed straight through.

The nucleus has a positive charged as some electrons were reflected straight back

Most of the mass is in the middle of the atom as occasionaly some particles got reflected back to sender

Question 4

How did Ernest Rutherfod discover what he did?

Answer 4

The Alpha scattering experiment.

He fired a beam of alpha particles through a thin gold foil.

Many went straight through but some was deflected a bit and a few were deflected straight back.

This showed that showed that most of the mass must be at the middle (the nucleus) also that the nucleus must be positivly charged

Question 5

What did Nieles Bohr discover?

Answer 5

The electrons orbit at different energy levels around the nucleus

Question 6

When did Niels Bohr discover what he did?

Answer 6

1911

N

Question 7

When did John Dalton discover what he did?

Answer 7

1804

N

Question 8

When did JJ Thomson discover what he did?

Answer 8

1897

N

Question 9

When did Ernest Rutherfod discover what he did?

Answer 9

1909

N

Question 10

When did James Chadwick discover what he did?

Answer 10

1932

N

Question 11

What did James Chadwick discover?

Answer 11

There are neutrons in the nucleus. This explained the differences in the Atomic mass number and mass numbers.

About 20 years after the nucleus was accepted

Question 12

What are the charges of the poton, neutron and electron?

Answer 12

Proton = +1
Neutron = 0
Electron = -1

Question 13

What is the radius of an atom?

Answer 13

1X10^-10Meters

Question 14

What is the radius of the Nucleus?

Answer 14

1X10^-15Meters

Question 15

How may an atom gain energy?

Answer 15

By absorbing EM radiation they move to a higher energy level

By releasing energy they move closer to the Nucleus

Question 16

What is the atomic number?

Answer 16

The amount of protons

Question 17

What is the mass number?

Answer 17

The amount of protons + neutrons

Question 18

Who first described an atom?

Answer 18

Democtrius

Question 19

What did Democtrius believe?

Answer 19

An atom was the smallest amount of matter that there was and that they were a solid sphere which couldn’t be divided to be any smaller

Question 20

What did JJ Thompson use to discover what he did?

Answer 20

Cathod rays which were used to fire electrons (eg in TV’s)

Question 21

Whata re the differences and similaritys between JJ Thompson and Rutherfod’s models?

Answer 21

JJ Thompson

No nucleus
Electrons were inbeded in the atom

Rutherfod
A densly charged positive nucleus

Both

There shaoe is spherical
They contain sub atomic particles
They have a nuetral charge

Question 22

How did Bohr discover that electrons orbited the nucleus at different energy levels?

Answer 22

Experiemtns also his calcuations lined up with experimental observations

Question 23

What could the nucleus be subdivided into?

Answer 23

Whole numbers of smaller particles with the same amount of possitvie charge

This was called the proton