CHEM1011 Lecture Notes - Lecture 11: Metallic Bonding, Nonmetal, Chemical Polarity

ChemActivity 90 Electron Arrangement (Where are the electrons?) Information: lonization Energy Electrons are attracted to the nucleus due its opposite charge. Therefore, energy must be supplied to pull an electron away from the leaving a positively charged species (cation) and a free electron. The ionization energy (IE) is the minimum energy required to remove an electron from an atom. Ionization energies are usually obtained experimenta y Critical Thinking Questions: 1. How many electrons does lithium have? 2. If electrons are distributed around the nucleus at various distances: a. Is the ionization energy for all of them the same? Un b. If not, which electron would have the lowest ionization energy: the electron closest to the nucleus or the electron that is farthest from nucleus? it rs lawest for the electron fart 3. a. As the atomic number increases, does the charge in the nucleus get stronger or mucwuS weaker? the cha in the nucuus %ts Stronger b. Would it require more or less energy to remove an electron as the charge changes? 4. Work as a team to predict the relationship between E and atomic number by making a rough graph of IE vs. atomic number. Do not proceed until you have finished your graph. Atomic Number

6) Calculate the effective nuclear charge for oxygen. (2) 7) True or False (9) Effective nuclear charge is the positive charge experienced by the electron from the nucleus and it increases from left to right across the period a. b. Effective nuclear charge slightly decreases going down a family. c. Atomic radius tends to decrease moving from left to right within a period due to the increasing principal quantum number. Anions are larger than their parent atoms because electrons are added to the valence shell increasing the electron-electron repulsion. d. e. The Zett for chlorine is larger than that of magnesium. f. Mg2* is smaller than Na because Mg2 has an extra electron. g. The ionization energy of Na* is significantly higher Na2 because it takes more energy to remove the inner shell core electrons. Ca, Cr, and Ni are metallic elements because they are on the right side of the periodic table. Sb, Al, and Ar are metalloids (semi-metals) because their properties fall between those of metals and those of non-metals. h. i. Calculate the electronegativity difference (ED) and then classify the bonding as either non-polar covalent (NPC), polar covalent (PC) or ionic (1). Use the electronegativity values from the power point in class. (10) 8) (NPC , PC,I) (NPC , PC,I) (NPC , PC,リ NPC , PC, I) (NPC , PC,I) ED ED a. C-H c. Na-C ED d. F-0 ED ED e. N-C