The atomic radius of hydrogen is calculated by measuring the internuclear distance between two hydrogen atoms in a hydrogen molecule (H2) and then dividing that distance by two.
Understanding Atomic Radius
The atomic radius of an element is a measure of the size of its atoms, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding cloud of electrons.
Measurement Units
- Atomic radii are typically measured in picometers (pm).
- One picometer is equal to 10-12 meters.
Calculating the Atomic Radius of Hydrogen
The calculation involves a straightforward approach based on experimental measurements:
- Measure the Internuclear Distance: The distance between the nuclei of two hydrogen atoms bonded together in an H2 molecule is measured. This distance is known as the internuclear distance.
- Divide by Two: Since the internuclear distance represents the distance between the centers of two atoms, dividing this distance by two gives the radius of one atom.
Example Calculation
- Measured Internuclear Distance: The internuclear distance in a hydrogen molecule (H2) is found to be approximately 74 pm.
- Calculation: To find the atomic radius, divide the internuclear distance by 2.
- Atomic Radius = 74 pm / 2 = 37 pm
Summary Table
| Measurement | Value (pm) |
|---|---|
| Internuclear Distance | 74 |
| Atomic Radius | 37 |
Practical Insights
- Experimental Basis: The atomic radius is determined through experimental methods, such as X-ray diffraction, which can measure distances between atoms in molecules.
- Hydrogen Molecule: The simplest diatomic molecule, H2, serves as a fundamental example for measuring atomic radii.
- Bonding Influence: The measured atomic radius can be influenced by the type of chemical bond the atom is involved in. For example, the radius might differ slightly in different bonding environments.
