Notes: Lewis Dot Structures Part 2 Chemistry Boon Date: 09/10 & 09/07 2012 Notes: Lewis Dot Structures Part 2

Catalyst: Mystery Molecules Write the name of the molecule described: This molecule consists of three atoms. Two of the atoms are of the same element. The molecule has two covalent bonds. This molecule makes up about 60% of a person’s body weight. It also covers about 70% of the earth. This molecule consists of 24 atoms. This molecule is made of atoms of 3 elements. It is the product of photosynthesis and the reactant of cellular respiration.

Catalyst Answer 1 Water! H2O

Catalyst Answer 2 Glucose C6H12O6

Biology rewind: macromolecules All organisms (living things) are made of macromolecules. Macromolecules are covalent compounds. The atoms in proteins, carbohydrates, nucleic acids, and lipids are all connected by covalent bonds.

Objectives I can draw Lewis structures of molecules with single, double, or triple bonds. I know that most biological compounds are formed by covalent bonds. I can state that one mole is 6.02 x 1023 particles.

Agenda Catalyst HW Review Lewis Dot Structures of Molecules Part 2 Carbon Monoxide Reading Activity Covalent Bonds Exit Slip Demonstration: Intro to the Mole Electron Configuration Practice

HW: Drawing Molecules WS An electron in the outermost energy level of an atom that can participate in bonding is called a valence electron. A structure in which atomic symbols represent nuclei and inner-shell electrons and in which dots are used to represent valence electrons is called a Lewis structure. A possible Lewis structure of a molecule for which more than one Lewis structure can be written is called a resonance structure.

HW: Drawing Molecules WS A covalent bond in which two atoms share two pairs of electrons is called a double bond. A covalent bond in which two atoms share three pairs of electrons is called a triple bond. A bond in which two atoms share one pair of electrons is called a single bond. A nonbonding pair of electrons in the valence shell of an atom is called an unshared pair.

HW: Drawing Molecules WS 8. Methanol CH3OH 9. Propane C3H8

HW: Drawing Molecules WS 10. Water H2O 11. carbon monoxide CO

HW: Drawing Molecules WS 12. Nitryl fluoride NO2F 13. SO32-

HW Vocabulary Crossword Down Proton Halogen 4. Cation Anion Isotope Electron configuration Noble gas Electronegativity Valence electron Mass number Across Atomic mass Atomic number Ion Period 13. Orbital 16. Nucleus 17. Crystal lattice Octet rule Alkali metal Group

Notes: Lewis Dot Structures part 2 Chemistry Date: 09/10 & 09/11 2012 Notes: Lewis Dot Structures part 2

Lewis Dot Structures: Part 2 In a covalent bond, atoms share electrons.

Lewis Dot Structures: Part 2 A covalent bond in which two atoms share two pairs of electrons is called a double bond.

Lewis Dot Structures: Part 2 A covalent bond in which two atoms share three pairs of electrons is called a triple bond.

Rules for covalent bonding Each bond is made up of 2 electrons Each atom wants to reach the same configuration as the noble gases Duet rule: Hydrogen wants 2 valence electrons Octet rule: All other atoms want 8 valence electrons Atoms will share electrons with other atoms so that both get a full valence shell

Drawing Lewis Dots for Compounds CH4 Steps: 1. Draw Lewis Dot structures for the individual atoms Double check your numbers of valence e- 2. Put central atom in the center 3. Put other atoms around 4. Draw 2 dots between each pair 5. Fill in other dots up to 8 (except for H) – if the atoms do not have enough valence electrons to reach 8, a double or triple bond is necessary. 6. Replace all bonded pairs with lines Central atom H H C H H

Double and Triple Bonds What happens when the total electrons do not match up with the Lewis structure? Example: O2 Draw the Lewis dot structure: Total valence electrons: O O O2 = 2 x 6 = 12 Single bonded structure uses too many electrons!

Double Bonds If the structure has too many dots, remove lone pairs from two atoms and replace with a double bond In a double bond, the atoms share 4 electrons Replace the bonded pairs with 2 lines Lone pairs O O

Double Bonds C O Some atoms can have more than one double bond Example: CO2 Total valence electrons: C = 4 O2 = 2 x 6 = 12 C O 16

Practice Carbon dioxide: CO2 Carbon monoxide: CO Sulfur dioxide: SO2 Nitrogen gas: N2 Dibromoethene: C2H2Br2 Ethylene: C2H4

Agenda Catalyst HW Review Lewis Dot Structures of Molecules Part 2 Carbon Monoxide Reading Activity Covalent Bonds Exit Slip Demonstration: Intro to the Mole Electron Configuration Practice

Carbon Monoxide Reading Carbon monoxide is a very dangerous gas. This article provides vital information about this deadly gas. Instructions: After each paragraph, ask yourself, “what did I just read?” and “why is this important?” If you cannot answer these questions, go back and reread the paragraph. After reading, answer the questions at the bottom of the page.

Agenda Catalyst HW Review Lewis Dot Structures of Molecules Part 2 Carbon Monoxide Reading Activity Covalent Bonds Exit Slip Demonstration: Intro to the Mole Electron Configuration Practice

Agenda Catalyst HW Review Lewis Dot Structures of Molecules Part 2 Carbon Monoxide Reading Activity Covalent Bonds Exit Slip Demonstration: Intro to the Mole Electron Configuration Practice

Mole Demonstration… Substance Name Observations Water H2O Sodium Chloride NaCl Sucrose C12H24O12 Oleic Acid C18H34O2 Potassium Chloride KCl The mole is a number we use to make counting atoms, ions, and molecules much easier. One mole is the number of carbon atoms in 12 grams of carbon-12. One mole is 6.022 x 1023 particles.

Homework Read textbook pp. 224-229 Due Wednesday 09.12: Read textbook pp. 224-229 Do problems: pp. 233 #1, 2, 4, 5, 6(a), 8(a) Due Thursday or Friday 09.13 or 09.14: Valence electron and ions review WS