Presentation on theme: "VSEPR Theory, Polarity, and using Electronegativity"— Presentation transcript:
1VSEPR Theory, Polarity, and using Electronegativity Ch. 16 Covalent BondingVSEPR Theory, Polarity, and using Electronegativity
2Covalent Bonds F F F F F F A. Types of Covalent Bonds Forms when 2 atoms share a pair of valence e-A. Types of Covalent Bonds1. Single Covalent Bond – two atoms share one pair of electronsEx: F2Unshared pair – e- not shared between atoms●●●●●●●●●●●●FFFF●●●●●●FF●●●●●●●●or●●●●●●●●●●●●●●What makes this bonding work?Atoms have 8 e- in their outer level to make them stable
3Covalent Bonds (cont.) H H H H H H Ex: H2 ●HHH●●or●Why does H2 only need 2 e- to be stable?first energy level only contains 2 e-
4Covalent Bonds (cont.) O O O O O O 2. Double Covalent Bond – 2 pairs of electrons are shared between atomsEx: O2●●●●●●●●OOOOOO●●●●●●or●●●●●●●●●●
5Covalent Bonds (cont.) N N N N N N 3. Triple Covalent Bond – 3 pairs of electrons are shared between atomsEx: N2●●●●NNN●●NNN●●●●●●●●●●or●●●●●●●●
6Covalent Lewis Dot Structures 1. Determine the # of valence e- in each atom in the molecule(# valence e- = roman numeral for group A atoms)2. The central atom is often the first atom written & is usually the atom with the least # of e-. (Exception – H can’t be the central atom). This is going to be the atom that needs to share the most electrons.
7Lewis Dot Structures for Compounds 3. Place the electrons around the atoms so each is stable (8 around it, except H – only 2)Examples:1. Br2●●●●●●●BrBrBrBr●●●●●●●●●●●●●●●●●●
8N N H H H H H H O C O C O O 2. NH3 3. CO2 ● ● ● ● ● ● ● ● ● ● ● ● ● ●
9C C Cl Cl Cl Cl Cl Cl Cl Cl H H O O H H 4. CCl4 5. H2O ● ● ● ● ● ● ● ●
10Covalent Bond Practice Problems: 1. CH OF22. H CHI33. PH CO2
11VSEPR Theory Explains the shapes of molecules. The VSEPR theory states: b/c electrons repel each other, molecules adjust their shapes so that the valence e- pairs are as far apart from each other as possible.
12Shape Formula Bond Angle Electrons Linear AX2 180o 4 shared 0 unshared Bent105o2 shared2 unsharedTrigonal PyramidalAX3107o3 shared1 unsharedTetrahedralAX4109.5oTrigonal Planar120oContains a double bond
13Bond PolarityPolar Covalent Bond – when 2 atoms are joined by a covalent bond and the bonding electrons are not shared equally
14Bond Polarity (cont.)Nonpolar Covalent Bond – when 2 atoms are joined by a covalent bond and the bonding electrons are shared equally
15Differences between polar, nonpolar, and ionic bonds
16How do you determine if a bond is polar, nonpolar, or ionic? Subtract the electronegativities of the bonding atoms (p. 405 in textbook)
17Electronegativity Differences & Bond Type Type of BondElectronegativity Difference RangeNonpolar Covalent Bond0.0 – 0.4Polar Covalent Bond0.5 – 2.0Ionic Bondgreater than 2.0
183. Potassium and Chlorine 4. Fluorine and Fluorine Tell if the bonds between the following atoms are polar, nonpolar, or ionic:1. Hydrogen and Carbon2. Oxygen and Carbon3. Potassium and Chlorine4. Fluorine and Fluorine5. Nitrogen and OxygenH 2.1C 2.50.4 NonpolarO 3.5C 2.51.0 PolarK 0.8Cl 3.02.2 IonicF 4.00.0 NonpolarN 3.0O 3.50.5 Polar
19Polarity of MoleculePolar Molecule – a molecule with a positive and negative end. Polar bonds must be present.
20Polarity of Molecule (cont.) It is possible to have polar bonds but not a polar molecule!Carbon dioxide has 2 polar bonds and is linear.Bond polarities cancel out b/c they are in opposite directions.CarbonOxygenOxygen
21Practice:Write the dot structure of the following molecules – then predict the shape and polarityI2PCl3H2SCHI3SiO2CH2O