Hydrogen is in the first column of the periodic table. At STP it is a diatomic gas. When cooled and/or under pressure it forms a crystalline solid of di-hydrogen molecules. Calculations indicate that under high enough pressure it may form a monatomic basis metallic crystal, and scientists are actively looking to find evidence of this. Results so far seem inconclusive.

However, lithium is also a first column element. But its solid is a monoatomic basis metal and NOT a dilithium crystal as we would expect based on hydrogen. Why not?

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  • $\begingroup$ Happy to! Any advice on what is not specific? I expect solid lithium to look like solid hydrogen. Solid hydrogen is a lattice of diatomic molecules, but lithium is a metal with a single atom basis. Does this wording work better? $\endgroup$
    – Paul Young
    Commented Jan 3, 2019 at 18:04
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    $\begingroup$ @PaulYoung No because all the links suggested do answer the question. $\endgroup$ Commented Jan 3, 2019 at 18:21
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    $\begingroup$ As far as molecular structure goes H2 is better compared with halides - single bond completes el. shell. $\endgroup$
    – Mithoron
    Commented Jan 3, 2019 at 18:37
  • $\begingroup$ I do think Mithoron's second link answer the Q, as well as his comment $\endgroup$
    – Paul Young
    Commented Jan 3, 2019 at 18:43


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