Multiple Choice
How many protons are present in the nucleus of a sodium (Na) atom?
2. Atoms & Elements
The Atom
Multiple Choice
Which of the following best describes the atomic number of an atom?
A
The number of protons in the nucleus
B
The number of electrons in the outermost shell
C
The total number of neutrons and protons in the nucleus
D
The mass of the atom expressed in atomic mass units
Verified step by step guidance1
Understand that the atomic number is a fundamental property of an element that uniquely identifies it.
Recall that the atomic number corresponds to the number of protons in the nucleus of an atom.
Recognize that the number of electrons in the outermost shell can vary due to bonding and ionization, so it does not define the atomic number.
Note that the total number of neutrons and protons in the nucleus is called the mass number, not the atomic number.
Remember that the mass of the atom expressed in atomic mass units refers to atomic mass, which is different from the atomic number.
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