To Do… OWL Lectures Discussion Chapter 11 (Part 2) due Wednesday, April 11 Chapter 12 (Part 1) due Friday, April 13 Lectures Continue reading Chapter 12 Discussion Chapter 12 text homework

Atomic Radius (Size) Increases down a group Hydrogen Francium Orbitals are getting larger and electrons fill further and further from the nucleus at higher energy levels

Atomic Radius (Size) Decreases across a row (period) – outer electrons in the same energy level Hydrogen Fluorine DECREASES! More protons in each element as you move across the row. More protons will create a stronger positive force, thus attracting the electrons more strongly, pulling them in and shrinking the size.

Figure 11. 36 Relative atomic sizes for selected atoms Figure 11.36 Relative atomic sizes for selected atoms. Note that atomic size increases down a group and decreases across a period. Figure 11-36 p265

Clicker Question Which of the following elements has the largest atomic radius? A) Ca B) Al C) N D) Sr E) F

p263

Ionization Energy Decreases down a group Hydrogen Francium Orbitals are getting larger and electrons fill further and further from the nucleus at higher energy levels. Electrons are not as tightly bound by the nucleus at higher energy levels so it takes less energy to remove an outer electron.

Ionization Energy Increases across a row (period) – outer electrons in the same energy level Hydrogen Fluorine INCREASES! More protons in each element as you move across the row. More protons will create a stronger positive force, thus attracting the electrons more strongly and pulling them in closer to the nucleus, requiring MORE energy to remove an outer electron.

Clicker Question Which of the following elements has the largest ionization energy? A) P B) Al C) Cl D) Ba E) K

Overall goal: Atomic Structure Chemical Bonding 3D Molecular Structure Molecular Properties

Overall goal: Atomic Structure Chemical Bonding 3D Molecular Structure Molecular Properties

Chemical Bond Force that holds groups of two or more atoms together and makes them function as a unit. Atoms will bond if the molecule is more stable than the two separated atoms (lower energy state).

Ionic Bonding

Na → Na+ + e–

Cl + e– → Cl–

Forming H2

Covalent Bonding

Clicker Question Imagine the bond formed in the carbon monoxide molecule (C-O). Which atom would you expect to have a greater attraction for the electrons in the bond? a) carbon b) oxygen c) They have the same attraction (both have n=2 as highest energy level with an electron). d) I do not know.

Polar Covalent Bonding

Figure 12.4 The three possible types of bonds. Figure 12-4 p271

Clicker Question How do lithium, fluorine, and cesium compare with regard to attraction for an electron in a shared bond? a) Li>Cs>F b) F>Cs>Li c) F>Li>Cs d) Li>Cs>F e) Cs>F>Li

Electronegativity

Table 12-1 p271

From the Periodic Table… Electron configurations Charges for ions in compounds (and thus formulas for compounds) Trends Atomic radius Ionization energy Electronegativity Polarity of Bonds