electrons
part of atom most a part of chemical reactions
nucleus
part of atom most a part of nuclear reactions
strong nuclear force
a powerful force of attraction that acts on the neutrons and protons in the nucleus, holding them together
Henri Becquerel
discovered radioactivity accidentally from the effect of uranium salts on photographic plates
Marie and Pierre Curie
discovered the elements polonium and radium and described the process of radioactivity
Ernest Rutherford (nature of radioactivity)
discovered alpha, beta and gamma radiation
alpha particle
a type of nuclear radiation consisting of two protons and two neutrons; has a positive charge
beta particle
a high-speed electron emitted in the decay of a radioactive isotope
gamma radiation
a type of nuclear radiation made of high-energy waves
nuclear decay
spontaneous change in the nucleus of an atom that emits nuclear radiation
stability of atoms
most atoms are incredibly stable (have been around "since the beginning")
unstable isotopes
radioactive isotopes that emit energetic particles, alpha and beta waves; the energy from atomic fragments is called radiation
what makes an isotope unstable?
having too many or too few neutrons compared to the number of electrons
it increases
what happens to the neutron to proton ratio as elements get larger?
alpha particle (properties)
identity = helium nuclei; composition 2 protons and 2 neutrons; charge 2+; penetration ability = low; mass = 4
atomic number = 2
beta particle (properties)
identity = high speed electron; charge = -1; penetrating ability = moderate; mass = 0; atomic number = -1
Np-237
what will Am-241 become if it undergoes alpha decay?
N-14
What will C-14 become if it undergoes beta decay?
fission (definition)
When one larger nucleus splits into two lighter nuclei. Process releases energy.
nuclear reactor or nuclear bomb
where does fission take place?
fusion (definition)
combining small nuclei to make a larger nucleus
-but high temperatures needed to overcome repulsion of the positive nuclei
sun and stars or hydrogen bomb
where does fusion take place
half-life
the time it takes for half of a radioactive sample to decay
4 half-lives decays to what percentage of the original?
1/2 x 1/2 x 1/2 x 1/2 = 6.25%