Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?
A) Atom 1: nucleus with 6 protons and 8 neutrons, surrounded by 6 electrons;
Atom 2: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons.
B) Atom 1: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons;
Atom 2: nucleus with 7 protons and 7 neutrons, surrounded by 7 electrons.
C) Atom 1: nucleus with 8 protons and 8 neutrons, surrounded by 8 electrons;
Atom 2: nucleus with 8 protons and 8 neutrons, surrounded by 7 electrons.
D) Atom 1: nucleus with 4 protons and 5 neutrons, surrounded by 4 electrons;
Atom 2: nucleus with 5 protons and 5 neutrons, surrounded by 4 electrons.
Answer: B