7.3 Nuclear rxns

Nuclear fission: the splitting of a more massive nucleus into two less massive nuclei, subatomic particles, and energy.   These reactions are often produced thanks to humans (it’s called an induced nuclear reaction)

These reactions often include the use of a proton These reactions often include the use of a proton. Remember that they type of atom you have is based on its number of protons, so there are 2 symbols used for this:   11p or 11H such as 24He + 714N  817O + 11H

These reactions usually begin by bombarding a nucleus with a neutron These reactions usually begin by bombarding a nucleus with a neutron. The symbol for neutron is:   01n

Here is how it works: a neutron collides with the nucleus of another atom (often uranium-235) adding to its mass and making the new nucleus very unstable.   The unstable nucleus splits into 2 smaller nuclei and also releases 3 neutrons and energy. It is this release of energy that humans use for their own means.

Because this reaction releases 3 neutrons, each of those neutrons can cause another reaction with 3 nearby nuclei. So one neutron frees up 3, those 3 each free up 3 more (grand total is now 9) each of those frees up 3 more (grand total is now 27)… This is called a chain reaction

Here is an example of a fission reaction  Here is an example of a fission reaction. How can you tell this process is fission? -it starts with just 1 neutron -there are 2 “new” elements formed on the product side -most of your examples start with uranium -there are 3 neutrons released on your product side 01n + 92235U  3792Rb + 55143Cs + 301n + energy

Nuclear Fusion: the process in which two low mass nuclei joining together to make a more massive nucleus.   This is a process that takes place in our sun (and suns throughout the universe). This process needs incredibly high temperatures and pressures. This is why we can’t harness its energy producing power (yet…)

The most basic version of this involves fusing together two hydrogen atoms to create helium. This is our sun’s main source of fuel. Most hydrogen atoms have 1 proton and 1 neutron. There are a very small percentage of hydrogen atoms that have 2 neutrons. Here are our nuclear symbols for hydrogen atoms:   12H or 13H

Here is the equation:   12H + 13H  24He + 01n + energy This particular reaction has a lot of potential for humans because it does not create any left over radioactive waste (like fission does). The problem is that so far it is very difficult to deal with the ridiculously high pressures and temperature needed for the reaction to take place.