Multiple Choice
Calcium has an atomic number of 20 and an atomic mass of 40. Therefore, a neutral calcium atom must have:
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2. Atoms & Elements
The Atom
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
The reactivity of an atom arises primarily from:
A
the total number of protons in its nucleus
B
the number of neutrons in its nucleus
C
the number of electrons in its outermost shell
D
the mass number of the atom
Verified step by step guidance1
Understand that the reactivity of an atom is mainly determined by how it interacts with other atoms, which depends on the electrons involved in bonding.
Recall that protons and neutrons are located in the nucleus and affect the identity and mass of the atom, but do not directly influence chemical reactivity.
Focus on the electrons, especially those in the outermost shell (valence electrons), because these electrons participate in chemical bonds and reactions.
Recognize that the number of valence electrons determines how an atom will gain, lose, or share electrons to achieve a stable electron configuration.
Conclude that the reactivity of an atom arises primarily from the number of electrons in its outermost shell, as these electrons control chemical behavior.
