# Homework Help: Elementary particle

1. Mar 13, 2008

### rojasharma

Sketch a diagram of the atom H-2, using the appropriate quarks and leptons. Label the particles in your diagram. I don;t knoq how to do this because my book does not have any example of this...:(

Last edited: Mar 13, 2008
2. Mar 13, 2008

### lavalamp

OK, protons and neutrons have three quarks each, up, up, down for the proton and down, down, up for the neutron. Up quarks have charge +2/3 and down quarks have charge -1/3.

H-2 has a proton and a neutron in the nucleus, and one electron in it's first shell, so you just need to represent the six quarks in the nucleus and the one electron in orbit.

Last edited: Mar 13, 2008
3. Mar 13, 2008

### rojasharma

sorry its He-2....even though i don;t have any idea how to do this....i am guessing...u and d are the quarks....(3 on top and 2 on the bottom of He). so there are 2 protons and 1 neutron...each proton will have 2 u and 1 d , neutron will have 1 u and 2 d. and lepton is electron which is 2 ...

4. Mar 13, 2008

### lavalamp

Helium-2 will have two protons and no neutrons then, and as I said, a proton has two up quarks and 1 down quark, also refered to as u and d yes.

The electron is a lepton yes, but does ont consist of any quarks, it is an elementary particle.

Edit: are you sure the question asks for Helium-2 though? He-2 has a very very short half life, only 3*10^-27 seconds.

5. Mar 13, 2008

### rojasharma

yes its written as 3 on top and 2 at the bottom of He....so this makes it He-2 right?

6. Mar 13, 2008

### lavalamp

No, that makes it He-3. The number of nucleons is 3, the atomic number is 2 (which is true for all isotopes of Helium). Helium-3 consists of two protons and one neutron, plus two electrons in orbit since it is an electrically neutral atom (as opposed to an ion).

7. Mar 13, 2008

### rojasharma

:)thanks

8. Mar 13, 2008

### lavalamp

Happy to help.