solid: a regular in space and constant in time collection of nucleuses and electrons
hydrogen atom
2 non-interacting hydrogen atoms
H2
optional 12nn – 10nnn
d = 0 if no pauli exclusion is taken into account
Other than your definition for a solid, the other answers agree with what was said in the video, you even added on the distance. For the definition of a solid, the quantum part has to be added.