Rapid Learning Center Presenting. Teach Yourself High School Chemistry in 24 Hours.

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1 Rapid Learning Center Chemistry :: Biology :: Physics :: Math Rapid Learning Center Presenting Teach Yourself igh School Chemistry in 24 ours 1/30 Chemical Bonding Rapid Learning Core Tutorial Series Wayne uang, PhD Kelly Deters, MA Russell Dahl, PhD Rapid Learning Center Rapid Learning Inc. All rights reserved. Rapid Learning Inc. All rights reserved. 1

2 Objectives By viewing this tutorial you will learn 4 types of bonding and the properties associated with those bond types Bond Polarity Valence Bond Theory 3/30 Chemical Bonding Concept Map Previous Previous content content New New content content Ionic Ionic Covalent Chemistry Chemistry Studies Polar Polar Covalent Metallic 4 types of bonding Matter Matter One type is Compounds Valance Bond Bond Theory Theory Most simple bonding theory 4/30 Rapid Learning Inc. All rights reserved. 2

3 Types of Chemical Bonds 5/30 Definition: Ionic Bond Ionic Bond Formed from the electrostatic attraction between positive and negatively charged ions due to transfer of electrons - contains both metals and non-metals. Na+ + Cl- - 6/30 Rapid Learning Inc. All rights reserved. 3

4 Definition: Covalent Bond Covalent bond Two non-metals share electrons. CC 7/30 Definition: Polar Covalent Bond Polar Covalent Bond two non-metals share electrons unevenly - electrons are closer to one atom than the other. CC NN 8/30 Rapid Learning Inc. All rights reserved. 4

5 Definition: Metallic Bond Metallic Bond Metal atoms join together and pool their electrons in a large network. Cu Cu Cu Cu Cu 9/30 4 Types of Bonds The different bond types have different properties. Ionic appens between Metals & Nonmetals Electrons are Transferred from one atom to another to create ions Characteristics igh melting points, brittle, often dissolve in water, conduct electricity when aqueous Covalent Non-metals Shared between 2 atoms Low melting points, do not often dissolve in water, do not conduct when aqueous Polar Covalent Non-Metals Shared unevenly between 2 atoms Medium melting points, sometimes dissolve in water, do not conduct electricity when aqueous 10/30 Metallic Metals Shared in a large pool with all the atoms Soft, Conductors of heat and electricity, do not dissolve in water Rapid Learning Inc. All rights reserved. 5

6 Bond Polarity 11/30 Definition: Polar Bond Polar Bond uneven sharing of electrons due to differences in electronegativity. The pull an atom has for electrons it s sharing in a bond Oxygen is more electronegative than Carbon. The Oxygen will pull on the electrons harder. The electrons will move closer to the Oxygen δ- δ+ OO CC O O δ- This will leave the carbon with a partial positive charge and Oxygen with a partial negative charge 12/30 Rapid Learning Inc. All rights reserved. 6

7 Electronegativity Trends In general, electronegativity: Increases Decreases 13/30 Common Element Electronegativities ere are 8 common elements & their electronegativities. Element Electronegativity 2.1 C 2.5 N 3.0 O 3.5 F 4.0 S 2.5 Cl 3.0 Br /30 Rapid Learning Inc. All rights reserved. 7

8 Determining a Polar Bond Look up the electronegativities for the two atoms. Determine the (absolute value) difference in electronegativity. Differences of: = Non-polar covalent bond = polar covalent bond > 1.4 = ionic bond If there is a polar bond, indicate it with an arrow being drawn toward the more electronegative element with a cross on the tail. 15/30 Example: Determine if each is a polar bond. C C = 2.5 = 2.1 Difference = 0.4 Non-polar C N C = 2.5 N = 3.0 Difference = 0.5 Polar Definition: Polar Molecules Polar Molecule Polar bonds do not cancel out and the molecule overall has partially positive and partially negative areas. δ- OO C C O O O O δ+ 16/30 Polar bonds, but non-polar molecule Polar bonds, polar molecule Rapid Learning Inc. All rights reserved. 8

9 Polar Molecules and Bond Geometry The manner in which we draw a molecule could affect our determination of polarity. δ- OO Drawing water in this way makes it appear to be a non-polar molecule. OO δ+ owever, water actually is shaped like this, and it is a polar molecule. 17/30 It is important to know the actual 3D arrangement to determine polarity of a molecule. This will be covered in the next tutorial. Determining Bond Types 18/30 Rapid Learning Inc. All rights reserved. 9

10 Bond Type Flow Chart Compound contains Metal & Non-metal Non-metals only Metals only Ionic bonding Electronegativity difference Electronegativity difference Metallic bonding Covalent bonding Polar Covalent bonding 19/30 Determining Bond Type Example Example: Determine the bond type of each: K O C O Metal & non-metal Ionic Bonding Non-metals C = 2.5 O = 3.5 Difference = 1.0 Polar Covalent C S Non-metals C = 2.5 S = 2.5 Difference = 0 Covalent 20/30 Rapid Learning Inc. All rights reserved. 10

11 Valence Bond Theory 21/30 Definition: Valence Bond Theory Valence Bond Theory Bonds are formed by the orbitals of atoms overlapping. Valence Bond s-orbital 22/30 Rapid Learning Inc. All rights reserved. 11

12 Sigma & Pi Bonds 23/30 Definition: Sigma Bond - 1 Sigma Bond (σ bond) A bond in which one pair of electrons is shared. Formed from the overlap of 2 s-orbitals. s-orbital 2 hydrogen atoms each have 1 electron in an s-orbital 24/30 Rapid Learning Inc. All rights reserved. 12

13 Definition: Sigma Bond - 2 Sigma Bond (σ bond) A bond in which one pair of electrons is shared. Formed from the overlap of 2 s-orbitals. sigma bond 25/30 2 hydrogen atoms each have 1 electron in an s-orbital As the atoms move together, their s-orbitals overlap and form a sigma bond Definition: Pi Bond - 1 Pi Bond 2 nd or 3 rd bond between two atoms. Formed from parallel p-orbitals. p-orbital O s-orbital O Only the orbitals and electrons involved in this bond will be shown 26/30 Rapid Learning Inc. All rights reserved. 13

14 Definition: Pi Bond - 2 Pi Bond 2 nd or 3 rd bond between two atoms. Formed from parallel p-orbitals. pi bond O O O O sigma bond 27/30 Determining Types of Bonds ow many sigma and pi bonds are in a molecule? σ π Each first bond between 2 atoms is a sigma bond All 2 nd and 3 rd bonds between 2 atoms is a pi bond Example: Count the sigma and pi bonds in the following molecule: C C C N σ π /30 Rapid Learning Inc. All rights reserved. 14

15 Diatomic and Polyatomic Compounds The Valence Bond Theory works well for diatomic compounds ( 2, O 2, etc.). But what about polyatomic compounds, such as C 4? More complex theories, such as ybridization and Molecular Orbital Theory are introduced in more advanced chemistry courses. 29/30 Tutorial Summary The type of of bond can be determined from the atoms involved, and each type has common properties 30/30 The Valence Bond Theory uses the overlap of atomic orbitals for diatomic compounds. The first bond between two atoms is a sigma bond, each addition bond is a pi bond Rapid Learning Inc. All rights reserved. 15

16 Rapid Learning Printable Tutorial - 15 Congratulations You have successfully completed the tutorial Chemical Bonding Rapid Learning Center Rapid Learning Center Chemistry :: Biology :: Physics :: Math What s Next Step 1: Concepts Core Tutorial (Just Completed) Æ Step 2: Practice Interactive Problem Drill Step 3: Recap Super Review Cheat Sheet Go for it! 32/30 Rapid Learning Inc. All rights reserved. 16