Nuclear Chemistry: Atomic Structure, Isotopes, and Radioactive Decay

What defines the atomic number of an element?

The number of protons in the nucleus.

What is the mass number of an atom?

The sum of the number of protons and neutrons in the nucleus.

What term describes atoms of the same element that have different numbers of neutrons?

Isotopes.

What are the three isotopes of hydrogen?

Protium, Deuterium, and Tritium.

How does the neutron count differ between Protium, Deuterium, and Tritium?

Protium has 0 neutrons, Deuterium has 1 neutron, and Tritium has 2 neutrons.

What is atomic weight?

The average mass of all naturally occurring isotopes of an element.

Approximately how many isotopes are known to exist (naturally occurring and synthetic)?

About 3,000.

What is the estimated total number of isotopes that could possibly exist?

Up to 7,000.

How many isotopes are considered stable on Earth?

About 250.

What is the upper limit for elements that have stable isotopes?

Lead (Pb).

What is the typical neutron-to-proton ratio for stable smaller elements?

A 1:1 ratio.

How does the required neutron-to-proton ratio change as nuclei get larger?

Larger nuclei require an increasing number of neutrons to remain stable.

What happens in the 'unstable region' of the table of nuclides?

Nuclei have too many protons and undergo spontaneous positron production.

How many stable isotopes does iron have?

Four.

Stable isotopes only....

exist for elements with atomic numbers of 82 (lead, Pb) and below

Fission

The splitting of large unstable isotopes. This is the basis for the first nuclear bombs as well as nuclear power plants.

Fusion

The combining of small particles in a highly exothermic process. It occurs within the sun and is potentially the ideal source of clean nuclear power to solve the world's energy crisis.

Radioactive Decay

The process by which the approximately 7000 isotopes decay to the 250 stable isotopes on Earth.

Alpha particle

4/2He or 4/2a

Beta particle

0/-1e or 0/-1B

Gamma radiation

0/0Y

Neutron

1/0n

Proton

1/1H or 1/1p

Positron

0/+1e or 0/+1B

Energy formula

E = mc^2

Nuclear energies magnitude

millions to billions of kJ/mol

Chemical bond energies magnitude

100s to 1000s of kJ/mol

Intermolecular forces magnitude

10s of kJ/mol

Types of radioactive decay to be responsible for

alpha decay, beta decay and gamma decay

Fusion technological challenges

Technological challenges have slowed progress on the development of fusion reactors.

a decay

Loss of 4/2He

฿ decay

Neutron converted to proton ejecting e-

y decay

Ejection of photon

ß+ decay

Proton converted to neutron ejecting positron and electron neutrino

Conservation of mass rule

The mass numbers on the left and right sides should add to the same number, and the protons on the left and right sides should add to the same number.