Based on the information in the table, which two elements are most likely in the same group, and why? Facts about Four Elements Element Atomic mass amu Total electrons Valence electrons Year isolated Bismuth Bi 209 83 5 1753 Nitrogen cap n 14 7 5 1772 Oxygen cap o 16 8 6 1772 Sodium Na 23 11 1 1807 Thallium Tl 204 81 3 1861
Answer
A
bismuth and thallium, because their atomic masses are very similar
B
nitrogen and oxygen, because they were both first isolated in the same year
C
sodium and thallium, because their names both end in the same suffix: -ium
D
bismuth and nitrogen, because they have the same number of valence electrons
Explanation
Elements in the same group of the periodic table have the same number of valence electrons. Bismuth and nitrogen each have 5 valence electrons, so they are most likely in the same group. Similar atomic masses, matching name endings, or the year an element was isolated do not determine its group.
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