Phys 4.5

Question 1

Rutherford’s Results

Answer 1

-Most alpha particles were undeflected
-Some alpha particles were scattered
-1/8000 alpha particles “back scattered” through a large angle”

Question 2

Rutherford’s Conclusions

Answer 2

-Must be mostly empty space as they did not interact with repulsive charge
-All positive charge and most of mass concentrated in small dense nucleus
-Negative charge is a cloud of electrons surrounding nucleus

Question 3

Proton Number (Z)

Answer 3

The number of protons in the nucleus.

Question 4

Mass (Nucleon) Number (A)

Answer 4

The number of protons and neutrons in the nucleus.

Question 5

Isotopes

Answer 5

Atoms of the same element with the same number of protons but different number of neutrons.

Question 6

Atomic mass unit (u)

Answer 6

1/12 the mass of ¹²C = 1.66x10‐²⁷