Sorry !

Sorry guyss i forgot to tell you how to calculate the number of neutrons and atomic weight.
Well here's a little trick i use.
For elements with their atomic number even (i.e. divisible by two) just double it to get the atomic weight.
For elements with odd atomic number just double it and add one.
WARNING! THIS TRICK DOES NOT WORK WITH HYDROGEN, BERYLLIUM, NITROGEN AND ARGON!
Also to calculate the number of neutrons take the atomic weight and subtract the atomic number.
A+N=Z
Where A is the atomic number, N is the number of neutrons and Z is the atomic weight.
Hydrogen's atomic weight 1
Beryllium 9
Nitrogen 14
Argon 40.