Explain the discontinuities in the trend of increasing first ionization energy across a period with reference to the energy of the electron removed. Explain how these discontinuities provide evidence for the existence of energy sublevels.
Recall that transition elements have incomplete d-sublevels. Recognize their key properties, including: variable oxidation state, high melting points, magnetic properties, catalytic properties, formation of colored compounds, and formation of complex ions with ligands.
Explain the formation of variable oxidation states in transition elements. Deduce the electron configurations of ions of the first-row transition elements.
Explain why transition element complexes are colored. Apply the color wheel to deduce the wavelengths and frequencies of light absorbed and/or observed.