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Multiple Choice
Which of the following sets of elements all have exactly one valence electron (simplified main-group rule)?
A
, , ,
B
, , ,
C
, , ,
D
, , ,
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1
Recall that valence electrons are the electrons in the outermost shell of an atom and determine its chemical properties.
Identify the group number of each element in the periodic table, since elements in the same group have the same number of valence electrons.
Look for elements in Group 1 (alkali metals) and hydrogen, as these elements have exactly one valence electron according to the simplified main-group rule.
Check each set of elements given: the first set (F, Cl, Br, I) are halogens with 7 valence electrons; the second set (H, Li, Na, K) are in Group 1 with 1 valence electron; the third set (Be, Mg, Ca, Sr) are alkaline earth metals with 2 valence electrons; the fourth set (C, Si, Ge, Sn) have 4 valence electrons.
Conclude that the set containing H, Li, Na, and K all have exactly one valence electron.