Question

It all adds up worksheet

Answer 1

Atomic number and the number of protons are the same...
Neutrons = Mass number - number of protons
Electrons are same # unless there is a charge 
The whole number you see on the periodic table is the atomic number of the element which is also same as the number of protons

1) carbon - 14  ;  Mass number = 14 , Protons = 6 , Neutrons = 14 - 6 = 8 
                                Electrons = 6 

2) Lead - 208  ; Mass # = 208 , Protons = 82 , Neutrons = 208 - 82 = 126
                          Electrons = 82

3) Uranium - 239 ; Mass # = 239  , Protons  =  92,Neutrons = 239 - 92 = 147
                                 Electrons =  92

4) Uranium - 238  ; Mass # = 238 , Protons = 92 , Neutrons = 238 - 92 = 146
                                   Electrons = 92 

5) Tin - 118  ; Mass # = 118 , Protons = 50 , Neutrons = 118 - 50 = 68
                         Electrons = 50