binary hydrides contain hydrogen bonded to one other element, examples include $\ce{LiH}$ and $\ce{HCl}$. the properties of the hydrides varies greatly. $\ce{HCl}$ dissolves in water to form hydrocholic acid whereas $\ce{LiH}$ forms an alkali solution.
when a hydride contains an electropositive element (Li) we can say that the hydrogen is hydridic, with an oxidation state of -1. any group 1 or 2 hydride is hydridic and ionic
protic hydrides are formed when hydrogen forms a binary compound with an electro negative group like chlorine. hydrogen has an oxidation state of +1 in these compounds
the ionization of hydrogen is very high because the electron is so tightly bound to the nucleus and so it doesn’t like to form positive ions. for this reason, protic hydrides are covalent and hydridic are ionic. partial positive and negative charges are also found on hydrogens.
$$ \ce{MH} $$
$$ \ce{2Na + H2 -> 2NaH} $$
these compounds are ionic an take the NaCl structure in their crystal lattice. they dissolve in molten alkali halides and can be electrolysed to produce hydrogen and the most reactive metal present
if the cations of hydridic hydrides have a high charge density then they can easily polarise the h-x bond. an trend of increased reactivity down the group 1 hydrides is created by increased ionic radius and decreased electronegativity of the metal ion, creating a lower enthalpy bond.
$$ \ce{MH2} $$
$$ \ce{Mg +H2->MgH2}
$$
beryllium is a bit of an outlyer in group 2 hydrides. it requires different processed for synthesis and has a different structure, forming a covalent structure of multiple chains held together by hydrogen bonds. in this structure, hydrogens bridge between 2 Be atoms with 3-centre, 2 electron bonding
upon solvation, group 2 hydrides (apart from $\ce{BeH2}$) form hydrogen gas an alklai solution of their respective hydroxide.