A single neutron drifts into a lump of uranium-235. One nucleus absorbs it. An instant later that nucleus has split into two smaller nuclei, a large amount of energy has been released, and three fresh neutrons are flying outward.
In the last topic you saw what makes a change nuclear: the protons and neutrons of the nucleus itself are rearranged. You have also just seen that nuclear changes release around a million times more energy than chemical changes, kilogram for kilogram. This lesson describes the first of those changes up close: the heaviest nuclei can split.
A heavy nucleus can split into two smaller nuclei.
Usually the split starts when the heavy nucleus absorbs a neutron.
The split releases two or three fresh neutrons.
The split also releases a large amount of energy.
Uranium-235 absorbs a neutron and splits into a barium nucleus and a krypton nucleus, plus three neutrons.
Each of the two smaller nuclei has fewer protons than uranium has, so each is a different element.
What those two or three fresh neutrons can start is the next lesson's story.
A uranium-235 nucleus absorbs a slow neutron and splits. Name everything the fission releases.
The nucleus splits into two smaller nuclei; for uranium-235 the register case is a barium nucleus and a krypton nucleus.
The split releases fresh neutrons, two or three of them; here, three.
The split also releases a large amount of energy.
The fission releases two smaller nuclei (barium and krypton), three fresh neutrons, and a large amount of energy.
A heavy nucleus splits into two smaller pieces. Each piece has fewer protons than the original nucleus had. Is each piece the same element as the original?
The proton count alone fixes the element.
Each piece's proton count has changed from the original's.
A changed proton count makes a different element.
No. Each piece is a different element from the original nucleus.
During nuclear fission, what happens to the heavy nucleus?
Besides the two smaller nuclei and the released energy, what else does a fission release?
Nikau says: 'A fission usually starts when the heavy nucleus absorbs a neutron.' Is Nikau correct?
A uranium-235 nucleus absorbs a slow neutron. Usually, what happens next?
Uranium-235 has 92 protons. It absorbs a neutron and splits into a barium nucleus and a krypton nucleus. Which statement about the two product nuclei is correct?
A heavy nucleus splits into two smaller nuclei, releasing neutrons and energy. What is this nuclear change called?