Multiple Choice
In an atom, which part is primarily responsible for chemical bonding (and thus chemical reactivity)?
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9. Electrons in Atoms and the Periodic Table
Valence Electrons of Elements (Simplified)
Multiple Choice
Which element has two valence electrons?
A
Aluminum (Al)
B
Magnesium (Mg)
C
Sodium (Na)
D
Chlorine (Cl)
Verified step by step guidance1
Understand that valence electrons are the electrons in the outermost shell of an atom, which determine the chemical properties and reactivity of the element.
Recall that elements in the same group (vertical column) of the periodic table have the same number of valence electrons.
Identify the group number of each element: Aluminum (Al) is in group 13, Magnesium (Mg) is in group 2, Sodium (Na) is in group 1, and Chlorine (Cl) is in group 17.
Recognize that group 2 elements have two valence electrons, so Magnesium (Mg), being in group 2, has two valence electrons.
Confirm that the other elements have different numbers of valence electrons: Aluminum has 3, Sodium has 1, and Chlorine has 7 valence electrons.
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