So i have to say the techdroider render of the Pixel XL is likely wrong, considering it has essentially 0 bezel, I assumed some minor bezel when I synced up the sizes. But given the data available, and assuming the screen sizes are correct (Pixel 5.0, Pixel XL 5.5) then this should be pretty close.
Valency, the combining capacity of an element, is equal to the number of electrons needed, or required to be removed from the outermost shell of the atom of that element, to have a complete 'octet'. The helium atom has only the 1s orbital in its only shell, and it is completely filled with 2 electrons. Its electronic configuration is 1s2. Therefore, helium and the other inert gases with complete octets normally do not take part in chemical reactions. They are considered as zero-valent elements.
Each orbital has only two electrons, because no two electrons can have the same quantum energy.. So, for the valence shell of an atom with two shells, one S orbital and three P orbitals. Two electrons an orbital adds to...8. Hydogen, on the other hand, only has one shell. So, to fill it's valence shell, it only needs two electrons.