Chemical Bonding & Molecules Key

Name: _____________________ Per:_____ Outline Unit 4 – Chemical Bonding & Molecules Vocabulary Ionic bond Lewis dot structure VSEPR Theory melting point Covalent bond Electronegativity lone pair electrons HONC rule Metallic bond valence electron hydrogen Bond Polar ion & polyatomic ion intermolecular force single, double, & triple bond non-polar Crystal lattice intramolecular force octet rule Electrostatic attraction conductivity solubility nucleic acid, nucleotide, polynucleotide starch, polysaccharide, carbohydrate, monosaccharide polymers monomers Proteins, amino acids, polypeptide Lipids , triglycerides, glycerol & fatty acids 1. Compare an Ionic bond to a covalent bond to a metallic bond: Between what types of elements? What happens to the electrons? Ionic metal and a nonmetal Covalent Between 2 nonmetals Metallic between two metal atoms a transfer of electrons from one atom to another causing cations and anions Electrons are shared between atoms. Can be polar or nonpolar Electrons clouds overlap and for a “sea of electrons” melting point (high/low)? Soluble in H2O? Conducts electricity? Shapes it can form? High Yes Yes, but only when dissolved in water Crystal lattice Low Yes No VSEPR Shapes (tetrahedral, bent, etc.) High No yes Lots, it’s malleable and can form lots of shapes. 2. Elements to bond Bond Type How do you know? S & O Cl & Cl Mg & O Na & F Ag & Au Covalent (polar) Covalent (non-polar) 2 non-metals Ionic Ionic Metallic Metal and a Metal and a 2 metals non-metal non-metal 3. How does the electronegativity of the two elements bonding influence the bond type? (ex: 2 strongly electronegative elements bond vs. 1 strong & 1 weak). 2 non-metals electronegativity is an atom’s ability to pull electrons off of other atoms. Fluorine is “strongest” and any atom near fluorine is also highly electronegative. Generally, metals are less electronegative than non-metals . a metal (weak) is bonded to a non-metal (strong), the non-metal is usually able to pull the electrons away from the metal (ionic bond). When they are close to being equal in strength, they must share the electrons (covalent bond). 4. a. Draw the ionic structure of a NaCl as it would appear on the molecular level attraction (aka electromagnetic) keep these ionic compounds together? b. How does electrostatic a. Crystals are formed from ionic compounds. There is a repeating pattern of positive and negative ions holds it together. b. cations and anions (+ and – charges) are attracted to each other. We call that electrostatic attraction (sometimes known as electromagnetic attraction). It’s what holds ionic compounds together. 5. a. Indicate the bond type for each compound PI3 = covalent b. Draw a Lewis dot structure for each of the following: NaBr = Ionic N2= covalent 6. a. How many electrons are shared in a single bond, double bond and triple bond? Single bond – 2 Double Bond – 4 Triple Bond - 6 b. What type of bond do they occur between (ionic, covalent, metallic)? Covalent c. Compare the bond energy & length between atoms bonded with single, double, & triple bonds. Atoms that are single bonded have the LARGEST bond length & therefore are the easies to break so they have a LOW bond energy. Atoms that are triple bonded are the closest together & thus have the SMALLEST bond length between atoms & are the most difficult to break apart (thus a HIGH bond energy) 7. a. H2O b. NBr3 c. SiO2 d. SiCl3Br a) Correct VSEPR 3-D drawing: b) Is the molecule polar or non-polar? c) Draw the arrows to show partial charges where needed Polar Polar Polar Name of shape? Bent Non-Polar Pyramidal Linear Tetrahedral 8. What is the HONC rule? How does it help make drawing structural formulas easier for large, organic molecules? HONC 1234 is the rule that says Hydrogen will want to make 1 bond (has 1 valence and needs 1 more to get to 2) , Oxygen wants to make 2 (it has 6 valence electrons and needs 2 more to get to the octet rule), Nitrogen wants to make 3 bonds (it has 5 valence electrons and wants to get 3 more to get to the octet rule), and carbon wants to make 4 bonds (has 4 valence electrons and needs 4 more). - It helps in drawing structural formulas because you don’t have to draw all the Lewis dot structures to see how they will bond, you always know HONC 1234. 9. Explain why shape is important in terms of how your body functions. Shape is important because it can partially explain how molecules are sensed by your body’s sensory receptors. Examples of this include taste, smell, and how your brain communicates to your body using neurotransmitters. 10. a. Compare a Polar covalent bond to a Non-polar covalent bond. a. b. b. Give an example of each. In both cases electrons are shared, but in a polar covalent bond there is a “pull” to one side of the molecule causing a slight negative and positive end o water molecules are examples of polar Non- polar is when the electrons are shared equally. o O2 is an example of a non-polar molecule Polar= H2O Nonpolar= O2 11. a. How do 2 polar molecules interact with each other (attracted or not)? Attracted c. 1 polar & 1 non polar? Not attracted b. 2 nonpolar molecules? not attracted d. 1 polar & one ionic? attracted 12. Water has many unique properties due to the fact that hydrogen bonds occur between water molecules. a. Draw a picture of hydrogen bonds between 3 water molecules. b. Explain why hydrogen bonds are formed. Because water is polar (has charged ends), one water molecule is weakly attracted to charged ends of other water molecules. c. How does this affect the behavior of water molecules? Water sticks to other water molecules and any other polar or ionic substances (charges always attract) 13. Classify the following as being either a intermolecular or intramolecular force & explain why: hydrogen bond= metallic bond= covalent bond= ionic bond= Inter Intra Intra Intra 14. a. Why is the carbon atom the backbone to so many large, complex biological molecules (proteins, carbohydrates, lipids, and nucleic acids)? It’s so versatile because it has 4 bonding sites and can make all sorts of combinations with itself and other atoms. 15. Class Polymer Mononmer 2 common exs: a. Carbohydrates Polysaccharide monosaccharide b. Nucleic Acids c. Protein Poly- nucleotide Poly- Peptide Nucleotide Amino Acid Tri-glyceride Glycerol & fatty acids Starches & Cellulose/Fiber DNA & RNA Hair, skin, enzymes, meat, dairy….. etc. Saturated/ Unsaturated, Cholesterol, phospholipid bilayer d. Lipids