the nuclear model of an atom Flashcards
(24 cards)
define the term ion
an electrically charged atom of group of atoms formed by the loss or gain of electrons
how do negative and positive ions form
negative = by gaining an electron - more electrons than protons
positive= losing an electrons
Define nuclear fusion
when two light nuclei join to form a heavier nucleus and release energy
what does nuclear fusion require
requires extremely high temperatures to maintain
is there a small of large amount of energy released in nuclear fusion
huge amount of energy is released
which releases more energy, nuclear fission or nuclear fusion?
nuclear fusion
why is nuclear fusion not currently a viable way to produce energy on earth?
with current equipment and techniques, the energy required in greater than the energy produced, resulting in a net energy loss
explain why the difficulty of generating energy through nuclear fusion
fusion requires very high temperatures which in itself requires large quantities of energy and also requires casing that can withstand them
what is nuclear fission?
the splitting of large, unstable nuclei to form smaller more stable nuclei
and the emission of spare neutrons
give an example of a fissionable isotope
uranium - 235
what usually needs to happen to induce fission?
the unstable nuclei must absorb a neutron
spontaneous fission ( where no neutron absorption occurs) is rare
along with two smaller nuclei what else is emitted in fission reactions?
two or three neutrons
gamma rays
energy
what form of energy do all fission products have?
Kinetic energy
what takes place during a chain reaction in a nuclear reactor?
an unstable nucleus absorbs a neutron
the nucleus undergoes fission and releases 2 or 3 further neutrons
these induce more fission which results in a chain reaction
what is the consequence of an uncontrolled chain reaction?
the rate of fission events becomes to high and results in the production of too much energy
this can lead to a nuclear explosion
how is the chain reaction in fission reactor kept under control?
control rods are positioned in between the fuels rods
the rate of fission is controlled by moving these rods up and down
the lower the rods are inserted, the slower the rate of fission
Nuclear fission advantages
-no polluting gases
-doesn’t use fossil fuels
-low fuel cost
-power stations have long lifetimes
what are the three main components of the core of a nuclear reactor and their roles
moderator - To slow down the released neutrons
controls rods - To absorb some of the released neutrons to slow down the reaction
fuel rods
nuclear fission disadvantages
-dangerous waste is hard and expensive to dispose of
-thermal pollution affects marine life
-accidents are rare but catastrophic
-bad public perception
-safety is expensive
Nuclear fusion disadvantages
needs plasma to be held at 100000000 K, and it cannot be held by gravity.
needs extremely high temps to stop atoms repelling each other
Expensive Construction Costs
Nuclear fusion advantages
-unlimited fuel
-barely any waste
-no greenhouse gases
Describe the process of fission for a uranium isotope in a nuclear power station
- a neutron is fired into a uranium nucleus to make it more unstable
- the uranium nucleus splits into two smaller nuclei, two or three more neutrons, and releases energy
- the new neutrons collide with more uranium nuclei, continuing the reaction
Why is a nuclear reactor lined with thick lead and concrete?
To absorb any radiation the isotopes emit and protect nearby people
Nuclear fusion takes place in…
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