Question

why gallium have 18 in third shell and titanium have 10 in third shell?​

Answer 1

Answer:

Due to differences in their atomic number

Answer 2

Gallium have 18 in third sell7

Each shell can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. ... For an explanation of why electrons exist in these shells see electron configuration.

For Titanium

For the fourth period/row, all of these electrons build the third shell to a maximum of 18 electrons. ... It adds its next electron to the third shell, not the outermost fourth shell. With a configuration of 2-8-10-2, titanium is out in the world and ready to bond with other elements.