Nuclear Chemistry

A Short Study

A Review

• Element – Chemical substance that cannot be divided by chemical means

– All atoms of the same element have the same atomic number

• Atom – A small piece of matter made of a nucleus and electron cloud(s)

– Nucleus contains protons and neutrons– Neutral atoms have equal numbers of

protons and electrons

Review Continued

• Atomic Number – the number of protons in the nucleus.

• Mass Number – The total number of protons and neutrons in the nucleus

• Ion – an atom that has lost or gained electrons

• Isotopes – atoms of the same element that have different numbers of neutrons

The New Stuff

1. Radiation – energy that is emitted from a source and travels through space

• Measured with a Geiger Counter

Have You Ever Been Exposed to Radiation?Is all radiation harmful?

More Terms

2. Non-Ionizing Radiation – radiation that does not have enough energy to ionize matter

3. Ionizing Radiation – High-energy radiation which is capable of knocking electrons out of atoms

4. Nuclear Radiation – radiation produced from the nucleus of an atom

5. Radioactive – unstable nucleus which spontaneously emits ionizing radiation

Types of Nuclear Radiation

Alpha Particle – (α) helium ions that have no electrons and are positively charged

Beta Particle – (β) electrons emitted at very high speed

Gamma Ray – (γ) high energy radiation which has no mass or charge

Positron – same mass as an electron but with a positive charge

Gamma Ray

Nuclear Decay

• Spontaneous• Starts as a parent• Becomes a daughter• Gives off heat (energy)• May continue as a series until a

stable atom is formed• Mass Number and electric charge

must be conserved during a nuclear change

Band of Stability

Types of Decay1. Alpha Emission

– Helium Nucleus is given off

2. Beta Emission– Electron (β-) or Positron (β+) is given

off

Decay Terms

• Half-life – the time it takes for one-half of the parent to decay

– Will the material ever be gone?

– What do we do with it?

– Some Examples of half-life

– Radioactive dating?

Fission

Nuclear PowerUses fission to generate electricity

Fission = The splitting of a large nucleus to produce smaller ones and energyBombardment with neutronsNeed critical mass that will sustain a chain

reactionControlled in a reactorUncontrolled in an explosion

Fusion = The combining of small nuclei to form larger ones releasing energy

Fission Reactor

Fusion Reactor

Synthetic Elements

• Transmutation – changing one element into another

– Carried out in1. Nuclear Reactors2. Nuclear Explosions3. Accelerators

• Transuranium – synthetic elements with an atomic number greater than 92