electron/positron annihalation?

Question

I have a test coming up and I just want to make sure Im clear on something:

Beta particles emit a positive B (positron) and a negative B (similar to the electron in the shells but this one comes from the nucleus) +B decay is proton rich so it turns a proton into a neutron which decreases the atomic number by 1, but the mass remains the same. -B decay is neutron rich so it turns it into a proton thus raising the atomic number by 1, while the mass remains the same. Both are types of isoberic decay and result in the formation of a more stable and different element than that of the parent.

Electron/positron annihalation occurs when an electron and positron collide resulting in 2 gamma rays that travel in opposite direction with 511kev each. this opposite direction is due to the conservation of momentum.

does this seem correct? and should i add anthing else..thanks!:)

i forgot to ask...where does electron capture fit into all this?

in my notes is says that "positron vs electron capture" are competing forms of decay. what exactly does that mean

Answer 1

hi,
Yup this is correct!!

Answer 2

Sounds good to me. Do you understand it? The only thing I would caution about is that some beta particle emissions escape the nucleus and go out into the world.