Is a water molecule 3 times the size of a Hydrogen & Oxygen atoms?
A picometer (pm) = one trillionth of a meter = 10-12 m.
A hydrogen atom is larger than a helium atom!
A hydrogen atom has a radius of about 53 pm whereas a helium around 31 pm, because helium's two protons exert a stronger positive pull, drawing its electrons closer to the nucleus, making it the smallest element.
What about the size of a water molecule compared to a Calcium or Potassium atom?
In conclusion, an atom could be physically bigger in size than a molecule!
