Carbon dating tree
These include nitrogen (78 percent), oxygen (21 percent), argon (0.9 percent), carbon dioxide (0.03 percent), varying amounts of water vapor, and trace amounts of hydrogen, ozone, methane, carbon monoxide, helium, neon, krypton, and xenon.
Cosmic rays, which contain even higher levels of energy than ultraviolet light, cause some of the atoms in the upper atmosphere to fly apart into pieces.
So in this reaction, a neutron is captured by the nitrogen atom and a proton is released.
Thus in the nitrogen atom, a proton is effectively converted into a neutron, which allows a Carbon to be produced.
The fact that it has seven protons is what makes it nitrogen.
Notice that the farther away the Mass Number gets from 12-13, the faster they break down (The blue numbers indicate half-lives, the time it takes for one half of the atoms in a sample to break down.).
So the farther the carbon is from the norm, the more unstable it is. They have too many neutrons so they breakdown, releasing a beta particle which effectively converts a neutron into a proton.
Since protons and neutrons weigh about the same, the atomic mass of ordinary carbon is 6 6 = 12.
It is called "Carbon-12," which is abbreviated "C." The fact that the atom has six protons is what makes it carbon.