Modern Atomic Theory

Question 1

John Dalton Model

Answer 1

• Matter is made of tiny solid spheres called atoms
• All atoms of the same element are identical
• Billiard Ball Model

Question 2

J.J Thomson

Answer 2

• Discovered electrons which he assigned a negative charge
• Raisin Bun Model

Question 3

Ernest Rutherford

Answer 3

• Discovered the protons
• Electrons fly randomly around the nucleus in an electron cloud
• Most of an atom is empty space
• Nuclear Model
• Named the center the nucleus

Question 4

Rutherford Experiment

Answer 4

• Fired positively charged particles at a piece of gold foil
• Most passed through so atoms are not solid

Question 5

Bohr’s Model

Answer 5

• Electrons orbit in the nucleus in fixed paths
• Energy of electrons is quantized (only certain values allowed)

Question 6

Grounded state of an electron

Answer 6

• Close to the nucleus
• Low potential energy

Question 7

What happens when an atom absorbs energy?

Answer 7

• The electron transitions to a higher energy level (excited state)
• Higher potential energy

Question 8

What happens when the electrons fall back closer to the nucleus?

Answer 8

• Potential energy decreases and the energy is given off as photons