Multiple Choice
Given the following atoms and their atomic masses: Hydrogen (1.008 u), Carbon (12.01 u), Oxygen (16.00 u), and Iron (55.85 u), which atom has the highest atomic mass?
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2. Atoms & Elements
Atomic Mass
Multiple Choice
What is the mass number of an ion that has 105 electrons, 157 neutrons, and a +1 charge?
A
263
B
261
C
105
D
262
Verified step by step guidance1
Recall that the mass number (A) of an atom or ion is the sum of the number of protons (Z) and neutrons (N): \(A = Z + N\).
Understand that the number of electrons is related to the number of protons and the charge of the ion. For an ion with charge +1, the number of electrons is one less than the number of protons: \(\text{electrons} = Z - 1\).
Use the given number of electrons (105) and the charge (+1) to find the number of protons: \(Z = \text{electrons} + 1 = 105 + 1\).
Use the given number of neutrons (157) and the calculated number of protons to find the mass number: \(A = Z + N = (105 + 1) + 157\).
Sum the values to express the mass number, which represents the total number of protons and neutrons in the ion.
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