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p6 (atom basics (consist of a nucleus made up of protons and neutrons…
p6
atom basics
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protons = positively charged, neutrons = neutral, so nucleus has an overall positive charge
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isotopes have same number of protons but different number of neutrons, so different nuclear mass but same nuclear charge
most isotopes tend to be unstable and radioactive, so they give out nuclear radiation and may decay into other elements
energy levels
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an inner electron can move up one or more energy levels if it absorbs EM radiation with the right amount of energy
when it moves up, it moves to a partially full or empty shell and is excited
the electron falls back to its original energu level and loses the same amount of energy it absorbed, the energy is carried away by EM radiation
the part of the EM radiation is from depends on its energy (which depends on the energy levels the electron moves between), a higher energy means a higher frequency of EM radiation
radiation
when radiation travels through a material it collides with the material's atoms, slows or stops the radiation
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alpha doesn't go far, beta quite far, gammer has the longest range
count rate
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further the radiation has the travel, higher the chance it will be asborbed by the material it is travelling through
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alpha blocked by paper, beta blocked by thin aluminium, gamma blocked by thick lead
flourescent tubes
contain mercury vapour, electrons accelerated through the vapour, ionises some mercury atoms, produces more free electrons
free electrons collides with electrons in other mercury atoms, electrons in mercury atoms are excited to higher energy levels
excited electrons return to original energy levels, emit radiation in the ultraviolent range of the EM spectrum
phosphorus coating on the inside of the tube absorbs the radiation, exciting its electrons to higher energy levels, them go down energy levels, emits many different frequencies of radiation, all inthe visible part of the electromagnetic spectrum
alpha decay
two neutrons and two protons, like a helium nucleus
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beta decay
an electron, with virtually no mass
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for every beta particle emitted, a neutron becomes a proton in the nucleus
gamma decay
after getting rid of an alpha or beta particle, the nucleus may need to get rid of extra energy
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no mass or charge, just energy, doesn't charge the element of the nucleus that emits them
ionisation
if an outer electron absorbs radiation with enough energy, it can move so far that it leaves the atom
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the atom is now a positive ion, more protons than electrons
nuclear radiation
alpha, beta and gamma radiation can ionise atoms, so can also be called ionising radiation
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alpha particles are most, can't travel far through a substance without hitting an atom and ionising it, gamma particles are the least
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alpha
mass number decreased by 4, atomic number decreased by 2
beta
mass number doesn't change as it has lost a proton but gained a neutron, atomic number increases by 1
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