now the attractive force between electrons and the nucleus is influenced by shell number and the quantity of electrons. Now we can say here that as you increase the shell number of an atom, you're going to increase the distance between electrons and nucleus. Because remember the more shells you add, the further and further away they are from the nucleus and the further the electron is away from the nucleus than the lower the attractive force between them. Now, we can also say that as you increase the quantity of electrons within the same shell or sub shell, this would actually increase the attractive force because you're adding more electrons. But the distance the electrons are from the center from the nucleus is not increasing. So there's a building and more attraction between the electrons and the nucleus. Now in general, the periodic trend for effective nuclear charge is that it increases as you're moving from left to right across a period and up and going up a group. So as we're heading to the top right corner of the periodic table, we expect our effective nuclear charge to increase. So just remember that general pattern for effective nuclear charge.