Answer:
In atomic physics, the Bohr model or Rutherford–Bohr model, presented by Niels Bohr and Ernest Rutherford in 1913, is a system consisting of a small, dense nucleus surrounded by orbiting electrons—similar to the structure of the Solar System, but with attraction provided by electrostatic forces in place of gravity.
Explanation:
The molecules of solids are shrinked in there normal state . but as a heat energy is produced , the molecules starts curating fast and fast as temperature goes up . since they vibrate , they hit and collide each other breaking the bondings this increases the surface of area of the solid , and molecules consumes that space and they expand .
Divide that my the molar mass which is 23 so 1.4087 g