[methlover]

This is my first question regarding to gen chem, and I've been going over "1001 questions in MCAT: chemistry" by exam krackers.  So here's my first question of the day.

"The charge on one mole of electrons is given by Faraday's constant(F=96,500C/mol.) What's the total charge of all the electrons in 2 grams of He?"

I am familiar with this sort of question, and to solve this problem we need to know the total number of electrons in He.  But I don't understand how you can find the total number of electrons just by looking at the atomic number(# of protons) and the atomic weight(# of neutrons+protons.) 

Here is the book's explanation for this problem:  Each mole of helium has 2 electrons, since helium has atomic number 2 and numbers of electrons and protons are equal in a neutral atom.  I really don't understand this sentence at all.  So are they saying if it's a neutral atom(approximately same number of proton and neutron, then the number of electron per mole is going to be the atomic number? Could someone try to explain this better for me?  This seems like an easy question yet i find it a bit tricky on that finding total # of electrons.

[enahs]

You seem to be mixing up the electron and neutron.

Every element has a distinct number of protons. The neutral element has the same number of electrons as protons.
Protons have a +1 charge. Electrons have a -1 charge. Equal mixture of each has a charge of 0.

Neutrons have no charge, and are thus neutral (hence the word NEUTRon).

[methlover]

thanks. that helped