9. Apply the rules for naming and writing formulas for binary molecular compounds.

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1 Chemistry: Hood River Valley High School Unit 5 Note Pack and Goals Name: Period: Unit 5 Bonding, Chemical Names, and Formulas Unit Goals- As you work through this unit, you should be able to: 1. Understand the difference in properties between ionic compounds and covalent compounds. 2. Use electron dot structure to show the formation of single, double, and triple bonds and draw their structural formula. 3. Use VSEPR theory to predict the shapes of simple covalently bonded molecules. 4. Use electronegativity values to classify a bond as nonpolar covalent, polar covalent, or ionic. 5. Name and describe the weak attractive forces that hold groups of molecules together. 6. Distinguish between ionic and molecular compounds. 7. Relate cations and anions to metals and nonmetals. READ: 8. Distinguish between chemical formulas, molecular formulas, and formula units. Chapter 8, Apply the rules for naming and writing formulas for binary molecular compounds. Assignments: Activities, Labs & Test Description A1 A2 Covalent Bonding WS VSEPR Geometry WS Chemical formulas modelling activity Molecular Geometry PHET computer lab A3 A4 Bond Types and Intermolecular Forces WS Molecular Compounds Naming WS Molecular Geometry Modeling Intermolecular Forces lab Chemical Names and Formulas Unit 4 Test Late Lab Stamp Key Terms: non-metals, electronegativity,molecule, molecular compounds, chemical formula, molecular formula, polyatomic ions, single covalent bond, structural formula, unshared pairs, double covalent bond, triple covalent bond, VSEPR theory, non-polar covalent bond, polar covalent bond, dipole, van der Waals forces, dispersion forces, dipole interactions, hydrogen bonds Demo s: Boiling/Melting salt, sugar, coconut oil, ethanol, water, acetone, methanol, propanal, hexanol, vegetable oil, Intermolecular attractive forces with posters.

2 Chapter 8: Covalent Bonding Molecules and Molecular Compounds: a. What type of bond exists between the atoms in a molecule? i. The prefix co- means. Valence means, so means to b. Define molecule c. What type of elements are chemically bonded together in a molecule? d. Create a list of physical properties that molecules share: Page 225 top paragraph e. are the only elements that exist in nature as atoms. These are called, which means they exist as atom. f. There are also seven common elements that exist in nature as two atoms bonded into as a. They make a seven on the periodic table, they are: g. Molecules are electrically. 8.2 The Nature of Covalent Bonding Using Lewis Dot Structures to draw covalent bond. 1. Show the covalent bond(s) in a Fluorine molecule, F 2, 2. Show the covalent bond(s) in an ammonia molecule, NH 3, 3. Show the covalent bond(s) in an Methane molecule, CH 4 A. Define Single covalent bonds: atoms held together by one of shared electrons. B. Define double covalent bonds: atoms held together by two of shared electrons. C. Define triple covalent bonds: atoms held together by three of shared electrons. D. Define an Unshared Pair: A pair of electrons that is shared between atoms.

3 4. Show the covalent bond(s) in an oxygen molecule, O 2 5. Show the covalent bond(s) in a nitrogen molecule, N 2, 6. Show the covalent bond(s) in a silicon dioxide molecule, SiO 2, 7. Show the covalent bond(s) in a dinitrogen dihydrogen molecule, N 2 H 2, E. Define coordinate covalent Bond: One atom contributes bonding electrons: Try carbon monoxide, CO F. Define Polyatomic ion: a tightly bound group of atoms that collectively carry a. 8. Hydroxide ion, OH -1 (remember to add or remove electrons as needed) 9. Show the covalent bond(s) Sulfate ion, SO 4-2

4 10. Show the covalent bond(s) Sulfite ion, SO Show the covalent bond(s) Ammonium ion, NH Bonding Theories 1. VSEPR Theory. dimensional models of molecules depend on a. The of covalent bond on the central atom b. The types (,, ) of bonds c. The number of electrons on the atom. d. and bonds act like bond areas each. e. Some molecules have multiple atoms. Pick and choose from there. Shapes of Molecules # of Central Bond areas unshared pairs of electrons on central atom? Diagram Example Polar or Non- Polar? Tetrahedral Trigonal Planer

5 Linear Triatomic Pyramidal Bent Linear Diatomic 8.4 Polar Bonds a. Non-Polar Covalent: The elements have very electronegativity so they share. Look at H 2 b. Non Polar Covalent: Any perfectly molecule is also because there is not possibility of having a region of one vs a region of the opposite. Try CO 2 Copy Figure 8.4 (pg. 238) Electronegativity Differences and Bond Types Electronegativity Difference Range Most probably type of bond Example

6 c. Polar-Covalent: The elements in the bond have electronegative differences between. HCl H 2 O 1. Dipole = a molecule with poles, or opposite is called 8.4 Intermolecular attractions and Polarity A. Intermolecular Forces: Forces that hold together. These determine,, and states. 1. : forces between molecules. A. Forces: Weakest, caused by motion. More electrons = More = More A. : Polar molecules in which attract. 1. : Dipole forces that are strong b/c Hydrogen is bonded to very electronegative atoms (,,or ) Show the intermolecular attractive forces between NH 3, H 2 O, HF. What types of intermolecular attractive forces do these molecules have between eachother?

7 When determining the strongest type of intermolecular attractive forces between molecules. 1 st : Look at the molecular 2 nd : Look up & label the values 3 rd : Look for symmetry or asymmetry to see if there is a possible region of and another region of. Think North and South. Try these: C 2 H 5 OH SiO 2 BI 3 SeF 2

8 9.3 Naming Molecular Compounds 1. We use prefixes when naming binary molecular compounds: Refer to Table 6.5 and fill in the following: Prefix Number Prefix Number a. How do we name binary molecular compound?? b. Say the name of the first element, say the name of the second element, ending in IDE, and put the appropriate prefix in to indicate how many of each element there are in the formula: **If the prefix for the first element in a binary molecular compound is, it may be dropped. However, it must be said if it is for the second element. **Don t reduce the subscripts (like you did for binary ionic compounds) Name these binary molecular compounds Write formulas for the following molecules a. H 2 O b. N 2 Cl 4 c. SeCl 5 d. CO e. C 3 F 8 a. dinitrogen tetrafluoride b. sulfur hexachloride c. trinitrogen octoxide d. dihydrogen dioxide e. nonanitrogen pentasulfide f. S 6 O 9