# Electron charge question

1. Jan 3, 2010

### 2203312

Hi,
Sorry this is a Newbie question.
What is the electron charge of He-3 and He-4?

I am new to physics so Sorry.

Many thanks

2. Jan 3, 2010

### Staff: Mentor

He-3 and He-4 are isotopes of Helium. All isotopes of Helium have the same number of protons and thus electrons.

3. Jan 3, 2010

### 2203312

Ok, they are Isotopes of helium.
But do they have different charges or is the charge the same as helium?
and

What is the charge is it -2.1x10^-21

4. Jan 3, 2010

### ZapperZ

Staff Emeritus
These isotopes are neutral atoms! They have no net charge!

Zz.

5. Jan 3, 2010

### Staff: Mentor

As I said, all helium isotopes have the same number of protons & electrons, thus the same electron charge. (The most abundant helium isotope is He-4; that's what is usually meant when you just say 'helium'.)
Where does this number come from?

Edit: I assume by 'electron charge' that you mean the total charge of the electrons in the helium atom. But realize, as ZapperZ points out, that the net charge of the helium atom is zero--the number of protons equals the number of electrons.

Last edited: Jan 3, 2010
6. Jan 3, 2010

### 2203312

Ok,
Thanks anyway.

Since I don't know what I am talking about I give up.

7. Jan 3, 2010

### arunma

Is the number $-2.1\times10^{-21}$ supposed to be in Coulombs? Because that's about 1/100th the charge on an electron. Since the electronic charge, $1.6\times10^{-19}C$ is the fundamental charge, you can't have a number less than that.

(Yes I know, quarks come in 1/3 and 2/3 charges, but they're always found in pairs or triplets because of QCD restrictions.)