radioactivity Flashcards
radioactivity
The spontaneous breaking up of an
unstable nucleus with the emission of one
or more types of radiation
who discovered radioactivity
Henri Becquerel
Nonionizing radioactivity
Ultraviolet, visible, infrared, microwaves, radio & TV, power
transmission
Ionizing – More Dangerous
Radiation capable for producing ions [bonds broken] when
interacting with matter – x-rays, alpha, beta, gamma, cosmic rays
Which Elements Are Radioactive?
Most elements have radioactive isotopes BUT
any element with an atomic number greater
than 83 consists entirely of radioactive
isotopes
what is the heaviest naturally occurring
element
Uranium is the heaviest naturally occurring
element – most elements above 92 are artificially
created in nuclear research facilities
what did Pierre and Marie Curie do
–Purified pitchblende
–Discovered two new elements
* Polonium [after Poland] and
* Radium [giver of rays]
Define alpha particles
Alpha particles are composite particles consisting of two protons and two neutrons tightly bound together. They are Thrown out by unstable radioactive nuclei until they become stable
what is the charge of alpha particles
positive because they are attracted to negative charge
what is Americium 241 used for
Americium 241 is used in smoke alarms
what are alpha particles stopped by
Stopped by a few
cm of air or a sheet of paper
what charge do beta particles have
negative because they are attracted to the positive plate
define beta particles
high energy electrons Formed when a neutron is changed to form a proton plus an electron. Electron is then ejected from the nucleus.
what can beta particles pass through
pass through paper
and up to about 5mm of Aluminium
what does carbon-14 emit
beta particles
give an example of an element that emits beta particles
carbon-14
define gamma rays
High energy electromagnetic radiation. Pass straight through electric and magnetic fields so not charged.
what stops gamma rays
only stopped by thick layer of lead
What can gamma rays be used for
- Very dangerous carcinogenic
- Can also be used to cure cancer.
- Sterilising surgical instruments
- Cobalt-60 is a source.
define Nuclear Reactions
Radiation is emitted from the nucleus
Difference between nuclear reaction and chemical reaction
- Chemical reactions only involve electrons
– no new elements involved
– atoms only rearranged - Nuclear reactions form a new element
– what the alchemists tried to do.
Transmutation
The changing of one element to another
Isotopes
are atoms of an element
which have the same atomic
number [number of protons] but
different mass numbers due to
different numbers of neutrons
Radio-isotopes
are isotopes which
are unstable and give out
radiation
