Rapid Learning Center Chemistry :: Biology :: Physics :: Math Rapid Learning Center Presenting Teach Yourself igh School Chemistry in 24 ours 1/30 http://www.rapidlearningcenter.com Chemical Bonding Rapid Learning Core Tutorial Series Wayne uang, PhD Kelly Deters, MA Russell Dahl, PhD Rapid Learning Center www.rapidlearningcenter.com/ Rapid Learning Inc. All rights reserved. Rapid Learning Inc. All rights reserved. 1
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
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
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
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
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
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 2.8 14/30 Rapid Learning Inc. All rights reserved. 7
Determining a Polar Bond 1 2 3 Look up the electronegativities for the two atoms. Determine the (absolute value) difference in electronegativity. Differences of: 0 0.4 = Non-polar covalent bond 0.5 1.4 = 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
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
Bond Type Flow Chart Compound contains Metal & Non-metal Non-metals only Metals only Ionic bonding Electronegativity difference 0-0.4 Electronegativity difference 0.5 1.4 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
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
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
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
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 123456 123 28/30 Rapid Learning Inc. All rights reserved. 14
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
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. http://www.rapidlearningcenter.com 16