History of atoms and Isotopes

Question 1

Proton

Answer 1

Positive
Charge=+1
Mass=1

Question 2

Neutron

Answer 2

Neutral
Charge=0
Mass=1

Question 3

Electron

Answer 3

Negative
Charge=-1
Mass=Almost 0

Question 4

Plum pudding model

Answer 4

100 years ago, people thought the atom looked like a “plum pudding”- A sphere of positive charge with negatively charged electrons spread through it. The discovery of the electron led to the plum pudding model.

Question 5

Rutherford’s scattering experiment

Answer 5

Rutherford got two students to fire alpha particles at some gold foil. They were expecting them to go straight through but instead, some were deflected and some even bounced back. In light of new evidence, a new model of the atom, called the nuclear model, was adopted.

Question 6

Bohr’s model of the atom

Answer 6

Electrons exist at specific energy levels. An electron will move up to a higher energy level if it gains energy. An electron will move down to a lower energy level if it loses energy, emitting EM radiation in the form of a photon.

Question 7

Discovery of Protons

Answer 7

Later experiments showed that the positive charge in the nucleus could be split up into a whole number of smaller particles, each with the same charge. we now know these as protons.

Question 8

Discovery of neutrons

Answer 8

A scientist called James Chadwick provided evidence for a second type of particle in the nucleus, the neutron. Neutrons have no charge, and they help to overcome the force of repulsion between protons in the nucleus