Multiple Choice
Which of the following is closest to the atomic mass of oxygen (O) as listed on the periodic table?
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2. Atoms & Elements
Atomic Mass
Multiple Choice
Which of the following best describes the difference between atomic number and mass number?
A
Atomic number is the number of protons in an atom, while mass number is the total number of protons and neutrons.
B
Atomic number is the average mass of an atom, while mass number is the number of protons.
C
Atomic number is the total number of neutrons and electrons, while mass number is the number of protons.
D
Atomic number is the sum of protons and electrons, while mass number is the number of neutrons.
Verified step by step guidance1
Step 1: Understand that the atomic number of an atom is defined as the number of protons present in its nucleus. This number uniquely identifies an element.
Step 2: Recognize that the mass number of an atom is the total count of protons and neutrons in the nucleus, which together contribute most of the atom's mass.
Step 3: Note that electrons have negligible mass compared to protons and neutrons, so they are not included in the mass number.
Step 4: Differentiate between atomic number and mass number by remembering that atomic number = number of protons, while mass number = number of protons + number of neutrons.
Step 5: Use this understanding to evaluate the given options and identify the correct description of the difference between atomic number and mass number.
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