# Subtraction Word Problem

1) Here Is a Picture of the Three Isotopes of Carbon. Find Their Number of Neutrons.

The number of neutrons in the C-12 atom is
12 – 6 = 6

The number of neutrons in the C-13 atom is
13 – 6 = 7

The number of neutrons in the C-13 atom is
14 – 6 = 8

2) Nickel (Z = 28, a = 58) Has 30 Isotopes That Have the Same Atomic
Number. But Their Atomic Masses Range From a = 48 to a = 78. a) How Many Neutrons Does the Lightest Isotope of Nickel Have?
b) How Many Neutrons Does the Heaviest Isotope of Nickel Have?

1. The lightest isotope of nickel has A = 48.
so, the number of neutrons = 48 – 28 = 20
2. The heaviest isotope of nickel has A = 78
So, the number of neutrons = 48 – 78 = 30

3) Here Is a List of Isotopes of Plutonium. Find Their Number of Neutrons.

Isotopes Number of neutrons (N)
228Pu94
229Pu94
232Pu94
233Pu94
234Pu94
240Pu94
241Pu94
242Pu94
243Pu94
244Pu94
245Pu94
246Pu94
247Pu94

Isotopes Number of neutrons (N)
228Pu94 N = 228 – 94 = 134
229Pu94 N = 229 – 94 = 135
232Pu94 N = 232 – 94 = 138
233Pu94 N = 233 – 94 = 139
234Pu94 N = 234 – 94 = 140
240Pu94 N = 240 – 94 = 146
241Pu94 N = 241 – 94 = 147
242Pu94 N = 242 – 94 = 148
243Pu94 N = 243 – 94 = 149
244Pu94 N = 244 – 94 = 150
245Pu94 N = 245 – 94 = 151
246Pu94 N = 246 – 94 = 152
247Pu94 N = 247 – 94 = 153

4) Here Is a List of Elements With Their Atomic Mass And Atomic Numbers. Find the Number of Neutrons of the Elements.

Elements Number of Neutrons
98Tc43 N =
145Pm61 N =
209Po84 N =
210At85 N =
222Pn86 N =
227Ac89 N =
237Np93 N =
243Am95 N =
247Cm96 N =
247Bk97 N =
251Cf98 N =
257Fm100 N =
252Es99 N =
258Md101 N =
261Rf104 N =
259Tc102 N =
277Hs108 N =
266Sg106 N =

Elements Number of Neutrons
98Tc43 N = 98 – 43 = 55
145Pm61 N = 145 – 61 = 84
209Po84 N = 209 – 84 = 121
210At85 N = 210 – 85 = 125
222Pn86 N = 222 – 86 = 132
227Ac89 N = 227 – 89 = 138
237Np93 N = 237 – 93 = 144
243Am95 N = 243 – 95 = 148
247Cm96 N = 247 – 96 = 151
247Bk97 N = 247 – 97 = 150
251Cf98 N = 251 – 98 = 153
257Fm100 N = 257 – 100 = 157
252Es99 N = 252 – 99 = 153
258Md101 N = 258 – 101 = 157
261Rf104 N = 261 – 104 = 157
259Tc102 N = 259 – 102 = 157
277Hs108 N = 277 – 108 = 169
266Sg106 N = 266 – 106 = 160