Nuclear Chemistry Unit

Nuclear Chemistry Unit

Introduction to Radiation

Certain types of atoms are unstable or “radioactive” and decay into other atoms by emitting parts of their nuclei. The speed with which they decay and release radioactive particles or energy is described by the “half-life”. The “half-life” is defined as the time necessary for half of the atoms in a sample to undergo radioactive decay and change to another atom by releasing particles. This “half-life” is not affected by temperature, pressure, or concentration.

Prelab Questions:

What are the three types of radioactive particles? Give both the name and the symbol for each.

Nuclear equations can be balanced in a manner similar to chemical equations. In chemical equations, each side of the equation must have the same number of each type of atom. In nuclear equations, each side of the equation must have the same mass and the same nuclear charge. In nuclear equations, you don't need to worry about electrons—after all, electrons are located outside the nucleus. We balance nuclear equations by summing the mass number and the nuclear charge. Recall that an atomic symbol is written as shown below.

Using this information, balance the following equations. Remember, two requirements must be met:

1)The sum of mass numbers must be the same on each side of the equation.

2)The sum of nuclear charges must be the same on each side of the equation.

(a)

(b)

(c)

(d)

(e)

You will be using radiation sources that produce alpha, beta, or gamma rays in their decay process. Write a balanced the equations below for each of these reactions below.

a)The production of alpha particles by the decay of Polonium-210.

b)The production of beta particles by the decay of Strontium-90.

c)The production of gamma rays and beta particles by the decay of Co-60.

What are some ways that you can think of to reduce exposure to radiation?

Radiation Information Sheet

Radioactivity in Our Lives

Smoke detectors: Smoke detectors contain the radioactive element Americium. In a fire, smoke particles shield the radiation from hitting a detector which causes the alarm to sound.
Nuclear energy: The energy produced by the decay of 1 gram of a radioactive substance is over a million time greater than the energy obtained by burning 1 gram of coal.
Carbon dating: The age of ancient relics can be estimated by measuring the amount of radioactive carbon in the relics.
Food Irradiation: "Zapping" or food with radiation (basically giving the food a powerful X-ray) kills dangerous viruses and bacteria (such as the e-coli virus). This is being considered as a method to make foods safer.
X-rays: X-ray energy is shielded better by bone than by tissue. By putting a piece of x-ray sensitive film behind a person, an image of a persons bones can be produced.
Medical Diagnostics: For certain medical procedures, people are fed (or injected with) a "radioactive cocktail." The cocktail can be designed to target a specific organ and help doctors diagnose medical problems.
Scientific investigation: Radiation is one of many tools that astronomers, biologists, biochemists, chemists, geologists, and physicists use to advancing scientific discoveries.
Weapons: Nuclear weapons along with chemical weapons (a.k.a. nerve gases) are probably the most destructive and nondiscriminate weapons available today.

Human Exposure to Radiation

(from M. S. Silberberg. Chemistry: The Molecular Nature of Matter and Change, McGraw Hill: Boston, 2000, p. 1062.)

Natural Sources / Exposure (mrem/year) / Artificial Sources / Exposure (per Dose)
The Sun / 30-50 / Diagnostic X-rays
The Earth / Lung / 0.04-.2 mrad/film
ground (clay/soil) / 25-170 / Kidney / 1.5-3 rad/film
wooden houses / 10-20 / Dental / <1 rad
brick houses / 60-70 / Therapeutic Radiation / locally  10,000 rad
concrete houses / 60-160 / Other Sources
Air (mainly radon) / Jet flight (4 hrs) / 1 mrem
outdoor / 20 / nuclear testing / <4 mrem/yr
in wooden houses / 70 / nuclear power industry / <1 mrem/yr
in brick houses / 130 / Total Average Value / 100-200 mrem/yr
in concrete houses / 260
Food and water / 40

Effects of Radiation on Adults

(from M. S. Silberberg. Chemistry: The Molecular Nature of Matter and Change, McGraw Hill: Boston, 2000, p. 1063.)

Dose (rem) / Effect / Lethal Dose
5-20 / Possible damage to chromosomes / non lethal
20-100 / Temporary reduction in white blood cell count / non lethal
50+ / Temporary sterility in men / non lethal
100-200 / Vomiting, diarrhea, tiredness / non lethal
300+ / Permanent sterility in women / non lethal
500 / Bone marrow and intestine destruction / lethal to 50-70% pop. (30 days)
400-1000 / Acute illness, early deaths / lethal to 60-95 % pop. (30 days)
3000+ / Acute illness / lethal to 100% pop. (2 days)

Exps. 35 Page