Electron Repulsion and Trends

[Sophia Diaz - Dis 1B]

When describing a lot of trends I notice that the idea of electron repulsion comes up a lot, but I don't understand how it really relates to everything. How does electron repulsion in different atoms affect trends?

For example, how does electron repulsion cause the size of the atom to be smaller? Does this mean there are more or fewer electrons?

[kendallbottrell]

The more electrons there are, the stronger the electron repulsion. A larger cloud and more electrons would mean that the electron repulsion is high and for those atoms, it would be easier to lose the electrons, especially in the outer shells. This means that the elements with larger atomic radii also have lower ionization energy because it takes less energy to remove electrons from the outer shells.

Electron repulsion would make the size of the atom larger and there would be more electrons. When there are less electrons, there is less repulsion and the atom would be smaller.