Barrons SAT Subject Test Chemistry, 13th Edition

1. Ejection reduces the atomic number by 2, the atomic weight by 4 amu.


2. High energy, relative velocity


3. Range: about 5 cm in air.


4. Shielding needed: stopped by the thickness of a sheet of paper, skin.


5. Interactions: produces about 100,000 ionizations per centimeter; repelled by the positively charged
   nucleus; attracts electrons, but does not capture them until its speed is much reduced.


6. An example: Thorium-230 has an unstable nucleus and undergoes radioactive decay through alpha
   emission. The nuclear equation that describes this reaction is:

In a decay reaction like this, the initial element (thorium-230) is called the parent nuclide and the

resulting element (radium-226) is called the daughter nuclide.

Beta Particle

(fast electron) Negatively charged, 1-

1. Ejected when a neutron decays into a proton and an electron.


2. High velocity, low energy.


3. Range: about 12 m.


4. Shielding needed: stopped by 1 cm of aluminum or thickness of average book.


5. Interactions: weak because of high velocity, but produces about 100 ionizations per centimeter.


6. An example: Protactinium-234 is a radioactive nuclide that undergoes beta emission. The nuclear
   equation is:

Gamma

Radiation

(electromagnetic radiation identical with light; high energy) No

charge

1. Beta particles and gamma rays are usually emitted together; after a beta is emitted, a gamma ray
   follows.


2. Arrangement in nucleus is unknown. Same velocity as visible light.


3. Range: no specific range.


4. Shielding needed: about 13 cm of lead.


5. Interactions: weak of itself; gives energy to electrons, which then perform the ionization.

METHODS OF DETECTION OF ALPHA, BETA, AND

GAMMA RAYS