Question

The table below gives the numbers of protons, electrons, and neutrons in four atoms.

Atom Number of protons Number of electrons Number of neutrons
1 39 39 52
2 40 40 50
3 39 39 54
4 40 40 51

Based on the information that is given, which atom in the table has the highest mass?
1
2
3
4

Answer 1

Atom 3.

Mass ≈ protons + neutrons. A1 = 39+52 = 91, A2 = 40+50 = 90, A3 = 39+54 = 93, A4 = 40+51 = 91. Atom 3 has the largest mass number (93).