This question is from an introductory chemistry course:

What is the oxidation state of $\ce{H}$ in $\ce{NaH, HCl}$, and $\ce{LaNi5H}$?

I've looked in the textbook to no avail.

Google doesn't help me much either. It does tell me that $\ce{LaNi5H}$ is an "intermetallic" compound.

The best I've found is this:

Allen electronegativities also yield zero for the oxidation state of all such η² hydrogen atoms.

What is the justification? Preferably, is there an "intro to chem" level explanation for this?

This question is from an introductory chemistry course:

What is the oxidation state of $\ce{H}$ in $\ce{NaH}$, $\ce{HCl}$, and $\ce{LaNi5H}$?

I've looked in the textbook to no avail.

Google doesn't help me much either. It does tell me that $\ce{LaNi5H}$ is an "intermetallic" compound.

The best I've found is this:

Allen electronegativities also yield zero for the oxidation state of all such $\eta^2$ hydrogen atoms.

What is the justification? Preferably, is there an "intro to chem" level explanation for this?

This question is from an introductory chemistry course: what is the oxidation state of H in NaH, HCl, and LaNi5H?

I've looked in the textbook to no avail.

Google doesn't help me much either. It does tell me that LaNi5H is an "intermetallic" compound.

The best I've found is this:

Allen electronegativities also yield zero for the oxidation state of all such η2 hydrogen atoms.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4506524/

What is the justification? Preferably, is there an "intro to chem" level explanation for this?

This question is from an introductory chemistry course:

What is the oxidation state of $\ce{H}$ in $\ce{NaH, HCl}$, and $\ce{LaNi5H}$?

I've looked in the textbook to no avail.

Google doesn't help me much either. It does tell me that $\ce{LaNi5H}$ is an "intermetallic" compound.

The best I've found is this:

Allen electronegativities also yield zero for the oxidation state of all such η² hydrogen atoms.

What is the justification? Preferably, is there an "intro to chem" level explanation for this?