Atomic and Nuclear Phenomena

Question 1

What is the photoelectric effect?

Answer 1

When light of a high enough frequency (~blue to UV light) is incident on a metal in a vacuum, electrons are emitted from the metal

This is another example of energy transfer where light energy causes the electrical potential energy in an atom to increase, enough for an electron to escape, and left over energy is converted to KE in the atom.

Question 2

What is the mass defect?

Answer 2

The mass of a nucleus is slightly smaller than just the sum of masses of all protons and neutrons

The mass defect is a result of matter that has been converted to energy (E = mc^2)

Question 3

What is the binding energy?

Answer 3

the energy created in the nucleus that holds the nucleons within the nucleus. The mass defect is result of binding energy

Question 4

Difference between fusion and fission

Answer 4

Fusion is small nuclei combining to form a large nucleus

Fission is a large nucleus splitting into smaller nuclei

Question 5

Different types of decays

Answer 5

Alpha decay: emission of an alpha particle **decreases the mass by 4 and # of protons by 2
Beta-minus decay: neutron converted to proton to maintain charge after the negative-beta leaves **increases the # of protons by 1
Beta-plus decay: proton converted to neutron to maintain charge after beta-plus leaves **decreases the # of protons by 1
Gamma decay: emission of gamma-rays ** doesn’t change mass or atomic number of element

Question 6

What is the half life of an element

Answer 6

The time it takes for half of the sample to decay