CHEM 11200 Lecture Notes - Lecture 10: Valence Electron

• School: University of Chicago
• Department: Chemistry
• Course: CHEM 11200
• Professor: Kozmin

Document Summary

Transition metals always lose s electrons before d electrons. Only groups 1, 2, 7, and 8 and the transition metals are pertinent. The phenomenon where the filled shells between the nucleus and the valence shell prevent the valence electrons from feeling the full positive effect of the protons in the nucleus. Decreases across a period: no new shell so electrons feel the effect and are attracted to the nucleus. Increase down a group: new valence shells added and shielding occurs. Energy it takes to remove a valence electron from an atom. Decreases down a group: due to shielding having less of an attractive effect. Increases across a period: higher attraction to the nucleus. Energy associated with the addition of an electron to an atom. Negative: energy is released when electron is added. Positive: energy is required when electron is added.