Periodic trends

AR decreases going across a period which means the atom is getting smaller. This occurs because there are more protons pulling the electron cloud closer to the nucleus

AR increases going down a group which means the atom is getting bigger. This happens because there are more energy levels and the electron cloud is getting larger

Ionization energy increases across a period which means it will take more energy to remove an electron. This happens because there are more protons pulling on the electrons

Ionization energy decreases down a group which means it will take less energy to remove an electron. This happens due to the increase in energy levels which increases the distance between protons and valence electrons and increases shielding from inner electrons

Electronegativity increases across a period which means the atom is more able to attract (hog) the electrons This happens because there are more protons pulling on the electrons

Electronegativity decreases down a group which means the atom is less able to attract (hog) the electrons. This happens due to the increase in energy levels which increases the distance between protons and valence electrons and increases shielding from inner electrons