CH 101 1st Edition Lecture 8 Outline of Last Lecture I Reviewing Quantum Numbers II Atomic Structure and Properties A Core Electrons B Valence Electrons III Effective Nuclear Charge IV Trends on the Periodic Table Outline of Current Lecture I Review of Periodic Trends II Ionization Energy III Electronegativity Current Lecture I Review of Periodic Trends The trend for electronegativity is it increases as you move up and right across the periodic table As the atomic radius decreases electronegativity increases because the electron becomes closer to the nucleus as the radius decreases making the charge stronger REMEMBER to not include noble gases in this trend noble gases are neutral The trend for Ionization energy is the same as the trend for electronegativity up and to the right This is because as the radius of the atom gets smaller is becomes increasingly harder for an electron to leave the atom and form an ion Noble gases are also excluded from this trend These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II III The trend for effective energy is to the right and down the periodic table This trend correlates with the atomic number of the atom as the atomic number increases the effective energy increases due to the increase in electrons The trend for the radius of an atom increases as you move down and to the left of the periodic table Ionization Energy To determine which atom has a higher lower ionization level when shown an electron configuration chart you use the circle method This method works by circling the electron that is farthest from the nucleus or in other words on the highest energy level After circling the electrons compare the electron configuration charts and the atom with the highest ionization energy will have an electron circled that is closer to the nucleus In this chart A has the highest ionization energy and C has the lowest Electronegativity Use the box method to determine the highest and lowest electronegativity when comparing electron configuration charts Put a box square in the orbital where the next electron would go if that atom were to gain an electron The square closest to the nucleus has the highest electronegativity In this chart the atom that has the highest electronegativity is B and the lowest is A