Chemistry · Periodicity in Elements
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Which one of the following is larger in size than the oxygen atom?
- A
Fluorine
- B
Nitrogen
- C
Carbon
- D
Hydrogen
Atomic size generally decreases across a period from left to right due to increasing nuclear charge. Oxygen is to the right of carbon in the periodic table, so it is smaller. Therefore, carbon, being to the left of oxygen, is larger in size.
Fluorine has a smaller atomic size than oxygen because it is to the right of oxygen in the periodic table. As you move across a period from left to right, the nuclear charge increases, pulling the electrons closer to the nucleus and reducing the atomic radius. Fluorine has an atomic radius of 42 pm, which is smaller than oxygen’s 48 pm, making it an incorrect option.
Nitrogen is incorrect because, although it is larger than oxygen, it is not the only correct answer. Carbon is also larger than oxygen, and based on general periodic trends, carbon is even larger than nitrogen.
Carbon is even further to the left of oxygen in the periodic table, meaning it has a lower nuclear charge and a weaker attraction between the nucleus and the outermost electrons. This results in a larger atomic radius of 70 pm, which is significantly larger than oxygen’s 48 pm. Carbon is a correct option.
Hydrogen (H) is in the first period and has only one electron, making it one of the smallest atoms in the periodic table, much smaller than the oxygen atom, which has two electron shells.
Tagged under Chemistry · Periodicity in Elements · 2021