Isotopes and Atomic Mass Flashcards
what is the atomic number
the number of protons
what does the mass number equal?
protons + neutrons
what are isotopes?
atoms with the same number of protons but different numbers of neutrons
what is a mass spectrometer?
a thingy used to identify isotopes and their respoective abondances
What do you need to calculate the average atomic mass?
- the number of isotopes
- the masses of each isotope
- the % abundance of each isotope
what is radiation?
the emission of energy in the form of waves or fact moving particles. The energy carried by radiation can be transferred to matter. commond type: electromagnetiv waves
what is ionizing radiation?
it consists of waves/particles that carry enough energy to remove an electron from an atom/molecule turning it into a positive ion (x-rays and microwaves, can harm tissue)
is nuclear radiation?
ionizing radiation emitted from the nucleus
Describe nuclear radiation.
an unstable nucleus sonpatenously emits particles and eletromagnetic radiation
- can transform one type of atom into a different one
what is radioactivity? and what is the process called?
radioactivity is nuclear radiation that can trasnform one type of atom into a different one, it is called radioactive (nuclear) decay
What is a radioactive substance?
a radioisotope -> one that emits nuclear radiation
When is a nucleus unstable?
if it has too many or too few neutrons. If a nucleus has more than 83 protons, no number of neutrons can hold it together forever
Usually radioactive nuclei go through a series of decays before becoming stable
What are the three more common types of nuclear radiation?
- alpha particles
- beta particles
-gamma rays
What are alpha particles?
stream of fast moving helium nuclei -> a helium nucleus, which is a cluster of 2 protons and 2 neutrons
what are beta particles?
stream of fast-moving electrons
What are gamma rays?
high frequency electromagnetic radiation, that are often emitted along with alpha and beta radiation
What is beta radiation?
a nuclear decay process that ejects a high speed electron from an unstable nucleus.
In beta radiation how is an electron formed in the nucleus?
by a breakdown of a neutron into a proton an electron and an antineutrino
When does gamma emission primarily occur?
after the emission of a decay particle
Describe gamma radiation?
- a form a high energy electromagnetic radiation
- will not change the isotope or the element
wavelength of the emitted gamma radiation will be unique to each isotope - a significant health risk
- no mass
- no charge
What are the speeds of the different kinds of decay?
alpha - slow
beta - fast
gamma - very fast (speed of light)
What are the penetrating powers of the different kinds of decay?
alpha - low
beta - medium
gamma - high
What can an alpha particle be stopped by?
paper
what can a beta particle be stopped by?
aluminum
what can a gamma ray be stopped by?
lead
what is nuclear fusion?
two smaller nuclei come together to make a larger nuclei
where does nuclear fusion happen naturally?
in centre of stars
What produces more energy - nuclear fusion or fission?
fusion - it requires high heat to get reaction going
What is nuclear fission?
a heavy nucleus splits into lighter nuclei
- Nuclear fission usually needs to bombard the heavier nucleus with neutrons
- a tremendous amount of enery released
- any given nucleus ongoing fission may split into a number of different ways
What is carbon dating?
using half-life to date the age of organic objects
what does carbon-14 become during beta decay?
nitrogen-14.
- at time of death, organism stop absorbing carbon-14 -> since half-life in constant, the ratio of carbon-14 to nitrogen-14 provides a measurement of the age of the sample
what is half-life?
the time required for half of the nuclei in a given sample of a radioactive isotope to decay. Can rage from a fraction of a second to billions of years
what does rate of decay depend on?
identity of substance
What are the differences between nuclear reactions and chemical reactions?
nuclear: different isotopes of an element behave differently
chemical: different isotopes of an element behave the same
nuclear: reactions are not affected by chemical state
chemical: reactions depend on chemical state
nuclear: energy changes are very large
chemical: energy changes are comparatively small
