Chemistry Chapter 16 Nuclear Chemistry

radioactivity

the spontaneous emission of radiation energy and/or high energy particles from the nucleus of an atom

radioactive decay

involves the emission of a particle and/or energy as one atom changes into another (in most instances, the atom changes its identity to become a new element)

radioisotope

an isotope of am element that emits radiation

4 types of radiation

1. Alpha decay

2. Beta decay

3. Positron decay

4. Gamma radiation

alpha decay

gives off alpha particles, low energy, made of high speed Helium nuclei (2 neutrons + 2 protons) which has a positive charge; usually accompanied by the release of gamma rays; most elements undergo this decay

4/2 He or a

alpha decay symbol

beta decay

involves the transformation of a neutron in the nucleus to a proton and an electron; the electron (beta particle with 1 charge) is then ejected from the nucleus; the atomic number increases by one, while the atomic weight stays the same; often accompanied by gamma radiation

0/-1 e or B

beta decay symbol

gamma radiation

high energy rays that penetrate most substances easily (no charge'; the rays may be released by itself or with other forms of decay; a form of electromagnetic radiation that, when released, tend to make the nucleus more stable

y

gamma radiation symbol

positron

a positive electron (a form of antimatter); often designated by B+ (positive Beta decay)

positron emission

a rare type of emission occurs when a proton is converted to a neutron and a positron in the nucleus (positive charge); it is ejected and the atomic number will decrease by one while the atomic weight does not change

0/+1 B or e

positron emission symbol

what exposure to ration can cause

1. cancer

2. nausea, weakness, skin burns, internal tissue damage

targeted radiation

used in medicine to damage cancer cells so they cannot reproduce

penetrating ability

different for each type of emission

alpha particles

don't penetrate matter well as they are the largest and slowest; stopped by paper, metal foil, skin, clothing

beta particles

faster and smaller than alpha particles; they can be stopped by a piece of aluminum foil

gamma rays

the most penetrating of all and can be stopped by thick lead

positrons

dissolve when they collide with electrons producing gamma rays

atomic mass and atomic number

must add to the same number on the reactant and product side when determining nuclear reactions

half-life

the period of time needed for one-half of a given quantity of a substance to undergo a change

the emission of radiation

results in a change in atomic number and/or mass number; this results in transmutation

transmutation

one element changes into another element

product of radioactive decay

often unstable so additional transmutations will occur

stable (non-radioactive) nucleus

the final product of a series of radioactive transmutation

uranium decay chain

undergoes alpha and beta decay and releases gamma rays until it turns into stable lead

decay curve

shows the decay of radioactive atoms and the remaining radioactive sample