Ionization nrg: energy when an atom in the gas state loses ions. Electron affiniy: nrg released when an atom in the gas state gains an electron. 1rst ioniation nrg: closer the electron to the nucleus, the stronger the attraction to the nucleus, so it"s harder to remove em, so ionization nrg will be higher. Successive ionization nrgies: nrgs to remove the 2nd, 3rd, etc electrons. Tells us when we start a new row: we start when we get a dramatic drop in i. e which suggests that electrons are further form the nucleus. The difference b/w the ionization nrgs are a lot smaller in the transition metals that other elements (like non-metals) Lanthanide elements have ie"s very close to each other and their chemical properties are even more similar than transition metals. As we go across the row, the atoms get smaller and heavier. # of protons as we go across increases, so the protons hold the e- tightly.