specific charge

[wupwup]

hi guys. not sure if this is the right place but im having some trouble revising AS level physics. i need to know how to work out specific charge.

specific charge = actual charge / actual mass.

it asked to work it out for a Cs atom with mass number 133 and atomic number 55. i know the mass is 133X1.675X10to the -27.

but im not sure how to work out the charge.

i know it must be something to do with the difference between the number of protons and electrons. but i thought it must have 55 of both is the atomic number is 55? thanks for any help. josh

[Sphere]

You are correct, the number protons is equal to the number of electrons if you are assuming the atom to have a neutral charge. The atom could have more or less than 55 electrons but then it would be an ion, which should have been mentioned in the problem statement.

[wupwup]

ook thats what i thought. thanks.