# A new element has the symbol Y and seven valence electrons. What is the maximum number of hydrogen atoms that can bond to it?

A hydrogen atom has 1 outer electron, $1 {s}^{1}$. That means that it needs one electron to complete the s orbital (it's outer shell).
Since $Y$ has 7 valence electrons, this means that it can complete the outer shell of 7 hydrogen atoms. So a maximum of $7$ hydrogen atoms can bond to $Y$