If the element have 39 protons, that means that his atomic number is 39, being Yttrium the element. And, the number of protons is the same of the number of electrons, so, 39 electrons.
Since the element is neutral and has 39 protons s the atomic number of the element must be 39. Yttrium is the only element in the periodic table with atomic number 39.
Atomic number of an element is equal to the number of protons which is equal to the number of electrons. Since the element is neutral, the number of electrons in Yttrium is also 39.
