Textbook Question
Give the symbol of the element that has the (4.7)b. largest atomic size in Period 4
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9. Electrons in Atoms and the Periodic Table
Periodic Trend: Atomic Radius (Simplified)
Multiple Choice
Based on periodic trends in atomic radius, which atom is expected to have the smallest atomic radius?
A
Ar
B
Na
C
Mg
D
Cl
Verified step by step guidance1
Identify the elements given: Sodium (Na), Magnesium (Mg), Chlorine (Cl), and Argon (Ar).
Recall that atomic radius generally decreases from left to right across a period in the periodic table because the number of protons increases, pulling electrons closer to the nucleus.
Note that all these elements are in the same period (Period 3), so the trend applies directly to them.
Understand that Argon (Ar) is a noble gas at the far right of Period 3, so it has the highest effective nuclear charge and thus the smallest atomic radius among these elements.
Conclude that based on the periodic trend of decreasing atomic radius across a period, Argon (Ar) is expected to have the smallest atomic radius.
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