Using electric force to calculate number of protons

[dizzydani]

[SOLVED] using electric force to calculate number of protons

Homework Statement

a hydrogen nucleus and a nucleus of an unknown atom are stationary, 5.0x10^-10m apart, the electric charge on the hydrogen nucleus is 1.6x10^-19C.
express the charge you have calculated for the unknown nucleus as a whole number multiple of the charge on the hydrogen nucleus, you may assume this number is the atomic number of the unknown nucleus, ie the number of protons

Homework Equations

I used Fe= -ke Q1 Q2 / r^2

The Attempt at a Solution

my calculation gave me the charge on the unknown nucleus to be -2.39x10^-19C
however, when i try to turn this into some whole number compared to 1.6x10^-19, i either get 1.5 or 0.6, neither of which are whole numbers.
please help with this part of the question, even if its just a nudge as to what on Earth is actually being asked...
neither integers nor any similar work appears in my coursebook and my tutor isn't returning my emails.
please help

 

[Shooting Star]

my calculation gave me the charge on the unknown nucleus to be -2.39x10^-19C

How? Data seems to be missing here.

 

[dizzydani]

full equation

okay, so using Fe = -Ke Q1 Q2 / r^2

Fe = 5.5x10^-9 N
-Ke = -9.0x10^9 Nm^2C^-2
Q1 = 1.6x10^-19C
r^2 = 6.25x10^-20m^2

Q2 = 5.5x10^-9 x 6.25x10^-20 / -9.0x10^9 x 1.6x10^-19

Q2 = -2.39x10^-19C

but the main part of the problem is the part where i have to use the 2 number for Q to tell how many protons Q2 nucleus has... i just arent sure where to start with that part

 

[Shooting Star]

Fe = 5.5x10^-9 N

This was not previously mentioned.

r^2 = 6.25x10^-20m^2

How, with the given value of r=5.0x10^-10m?

 

[dizzydani]

ah-haa!

that was it, that was what was causing all my problems. i thought that because it said they were 5.0x10^-10m apart i thought that was the diameter, and that i wanted the square of the radius... i just calculated it all again and i get it now... its carbon...

thanks muchly

big hugs in cyberspace