Originally posted by SNGX1275
Here you go guys: (for those interested)
Well its hard to write atomic weight and atomic mass without doing it in a math program. So here is what I'm going to do. if I right 1:1H that means 1 proton and 1 neutron. 13:7C means 7 protons 6 neutrons.
So 1st we started with hydrogen and helium like I said in that previous post but here is how helium forms:
*1:1H + 1:1H +1:1H +1:1H ----> 4:2He
*This process is called
electron capture. It converts a proton to a neutron when it captures the electron.
*He production results in densification of core of stars which leads to a temperature increase.
*At about 100Million degrees Kelvin He fusion occurs:
4:2He + 4:2He + 4:2He ----> 12:6C with Intermediate Li, B, Be
*Carbon atoms form a catylist for further reactions
*CNO cycle (carbon nitrogen oxygen)
* 12:6C + 1:1H ----> 13:7N + gamma
* 13:7N ----> 13:6C + a Beta particle (positron)
* 13:6C + 1:1H ----> 14:7N + gamma
* 14:7N + 1:1H ----> 15:8O + gamma
* 15:8O ----> 15:7N + Beta
* 15:7N + 1:1H ---->
12:6C + 4:2He which is the catylist for the CNO cycle - its recycled. the 4:2He is an alpha particle when stripped of electrons.
* Alpha Particle Fusion
* 12:6C + 4:2He ----> 16:8O
* 16:8O + 4:2He ----> 20:10Ne
* 20:10Ne + 4:2He ----> 24:12Mg
* there are 9 more steps to this which continue all the way up through formation of 56:28Ni, that is the last of alpha particle fusion. I don't think I need to continue the pattern as it should seem obvious after 3 examples. (the nickel formed is radioactive, it decays to a stable Iron)
*
NOW 1 OF 2 THINGS CAN HAPPEN
1. Reaction continues until all of the He is used up, then the star fizzles out and forms a "White Dwarf" which has a cool dark Iron Core and the other elements that formed (smaller than Fe). Note: Our sun will take this path.
2.
This is the cool one
Neutron Capture occurs in Red Giant Stars
* 62:28Ni + 1:0n ----> 63:28Ni + gamma
Note: I must have temporarly fallen asleep during this class because I don't have in my notes how we got from that alpha fusion to 62:28Ni....
* 63:28Ni + 1:0n ----> 63:29Cu
* This is the process that formed all further elements
Now you might be subconsiously wondering why we have heavier elements than Iron on Earth, espically since our Sun is taking the wrong path. Well it simply means that our solar system is a result of at least 1 supernova explosion (red giants can do the whole supernova thing).
While I'm rambling on (you guys don't have to read the rest) I'll include some observations about elements in our Solar System.
1. As atomic # increases abundance generally decreases.
2. Oddo-Harkins Rule:
- Elements with even atomic #s are more stable than odd.
- Number of neutrons also has an effect on nuclear stability:
Proton_____Neutrons_____Mass_____# Of Stable Isotopes
Even_______Even________Even___________168
Even_______Odd_________Odd___________57
Odd________Even_______Odd______________50
Odd________Odd_________Even____________4 (Li, Be)
I'm tired of trying to get the spacing to line up, you'll just have to imagine they line up
.