Question

Question #36a13

Answer 1

Because as an ion, it exhibits +1 valency, similar to alkali metals.

Explanation:

In many cases, on ionisation, hydrogen forms `H^+` ion, which, due to a similar valency as that of alkali metals, exhibits metallic character in chemical reactions.

This is why it is often placed along with the metals.

As you observed, Hydrogen is actually is a non-metal and is capable of forming `H^-` ion too, which would have halogen-like behaviour. As a result, this position of Hydrogen is not completely accurate and is under debate.
Sometimes, in recent versions of the Periodic Table, Hydrogen is placed in the centre at the top of the table, owing to its unique properties.