Nuclear Chemistry

•Marie Curie discovered that there was something going on inside the Uranium atom that created the rays, she named this effect “radioactivity”

Nuclear Symbols

2 3 59 2U

Element symbol

Mass number (p+ + no)

Atomic number (number of p+)

Radioactive Decay Radioactivity◦when a nucleus spontaneously decomposes, forming a different nucleus and producing one or more particles.

Nuclear Equation◦Both the atomic number and the mass number must be conserved.◦ That is the sums of both on each side must be equal.

Radioactive ParticlesParticle Type Symbol Mass Penetrating

Power

Alpha Particle 4 Low Blocked by paper or clothing

Beta Particle 0 Moderate Blocked by metal foils

Gamma Ray 0 High Incomplete shielding by lead and concrete.

Types of Radioactive DecayType Definition End Result

Alpha-particle Production

Decay of the nucleus of a large atom that results in the formation of an alpha particle

Atomic mass reduced by 4 and atomic number is reduced by 2

Beta-particle Production

The net effect of beta-particle production is to change a neutron to a proton. Releases a beta-particle.

No change in mass number, but an increase in one of the atomic number

Positron Production

Positron has the same mass as an electron, but opposite charge. Not common.

No change in mass. But a decrease in one of the atomic number.

Electron Capture

A process in which one of the inner-orbital electrons is captured by the nucleus

Atomic number decreases by one, but the mass remains the same.

Gamma Rays Gamma rays are photons of electromagnetic radiation with high frequency and energy. Gamma rays are given off during other types of radioactive decay.

Half-life The time required for half of the original sample of nuclei to decay.

Half-life Concept

Decay Series A decay series will

occur until a stable

nuclide is formed.

Nuclear Fission http://www.teachersdomain.org/asset/phy03_vid_fission/

The process of splitting an atom. Releases an enormous amount of energy.◦1 mol of uranium-238 can produce about 26 million times as much energy as 1 mol of methane.

Nuclear FusionThe process of combining two light nuclei.

◦Produces more energy than fission.

http://www.teachersdomain.org/asset/phy03_vid_fusiontest/

Radiation may be absorbed by the medium it passes through.

Radiation can kill living cells or change the nature of living cells.

Effects of Radiation on Living Organisms

Making Use of Radioactivity Humans have the ability to harness and manipulate radioactivity for:◦National defense and weaponry◦Medical diagnosis and treatments◦Energy production◦Radioactive Dating

Radiation Detection

Approximate amounts of radiation can be detected by the following devices:•Film badge•Geiger-Muller counter•Scintillation counter

Radiation Detection

The film badge is worn on a lapel, the wrist, or finger, and detects the approximate accumulated dose of radiation over time.

People who work with radiation, such as x-ray technicians, will wear such a device.

Radiation Detection

The Geiger-Muller counter detects the approximate radiation present at any given time by counting electric pulses carried by gas ionized by radiation.

The Geiger-Muller counter would be used to detect an approximate radiation dose that a person has been exposed to, such as when the Fukushima nuclear power plant leaked radiation.

The scintillation counter can detect ionizing radiation. Some substances absorb. e

A scintillation counter would be used in border security, homeland security, and nuclear plant safety, among other things.

Radiation Detection

The scintillation counter can detect ionizing radiation. Some substances absorb ionizing radiation and emit visible light, or scintillate.