Bromine is the only nonmetal that is a liquid at room temperature. Consider the isotope bromine-81, . Select the combination which lists the correct atomic number, neutron number, and mass number, respectively.
A) 35, 46, 81
B) 35, 81, 46
C) 81, 46, 35
D) 46, 81, 35
E) 35, 81, 116

Question

Bromine is the only nonmetal that is a liquid at room temperature. Consider the isotope bromine-81,  . Select the combination which lists the correct atomic number, neutron number, and mass number, respectively.
A) 35, 46, 81 
B) 35, 81, 46 
C) 81, 46, 35 
D) 46, 81, 35 
E) 35, 81, 116

Quizplus · Accepted Answer

The atomic number represents the number of protons in an atom, and since bromine-81 is still an atom of bromine, it must have 35 protons (because bromine's atomic number is 35).

The mass number is simply the total number of particles in the nucleus, so this includes both protons and neutrons. We know that bromine-81 isotope contains 81 particles in the nucleus, so we subtract the atomic number (35) from 81 to find the number of neutrons:

81 - 35 = 46

Therefore, the correct combination is A) 35, 46, 81.

Bromine Is the Only Nonmetal That Is a Liquid at Room