Explanation: If children were running around with balloons filled with hydrogen gas, then they would catch fire. So the answer to your question is, its simply dangerous.
Atomic radius is the distance from the nucleus of an atom the outermost energy shell or energy level.
The atomic radii of metals are greater than the ionic radii since metals form ions by losing electrons.
Calcium atom has a larger atomic radius compared to magnesium atom because it has more energy levels. Calcium atoms have four energy levels while magnesium atoms have three energy levels.
