1. Molecules & Chemical Bonds
Packet #4
Chapter #2
Sunday, November 18, 2018

2. Introduction Compound Molecule Chemical Bonds
A substance consisting of two or more elements in a fixed ratio
Molecule
Two or more atoms held together by covalent bonds.
Chemical Bonds
Forces by which atoms are able to bond together.
An attraction between two atoms
Results from the sharing of electrons.
Results from the presence of opposite charges.
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3. Molecules
Chemical Formulas
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4. Introduction II Molecular Formulas Structural Formula
Says what the molecule is made of and how many they are
Structural Formula
Shows how the molecule is orientated in space
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5. Formulas in Biology II
Sunday, November 18, 2018

6. Types of Chemical Bonds
Covalent Bond
Ionic Bond
Hydrogen Bond
Polar Bond
Non-polar Bond
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7. Types of Chemical Bonds
Covalent Bonds
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8. Covalent Bonds I A bond in which electrons are shared.
Resulting in an compound more stable than the individual atoms
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9. Types of Covalent Bonds
Single Bond
A covalent bond in which a single pair of electron is shared between bonded atoms.
Two electrons are shared
Provides an angle of 109.5˚
Double Bond
Two pairs of electrons shared between two atoms
Four electrons are shared
Provides an angle of 120˚
Triple Bond
Three pairs of electrons shared between two atoms
Six electrons are shared
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10. Types of Covalent Bonds II
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11. Types of Covalent Bonds III
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12. Types of Chemical Bonds IV Saturated vs. Unsaturated Molecules
Indicates that there are ONLY single bonds
Unsaturated Molecules
Indicates that double, or triple bonds, are present.
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13. Saturated vs. Unsaturated
Unsaturated molecules allow the formation of kinks.
Kinks prevent fat molecules from sticking together.
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14. Types of Chemical Bonds
Ionic Bonds
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15. Ionic Bond
A bond that is formed by the attraction of two ions (cation & anion) of opposite charge
Cation
Positive charge
Anion
Negative charge
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16. Ionic Bonds II
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17. Types of Chemical Bonds
Polar Bond
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18. Polar Bond
A polar bond is formed because one atom, of the compound, being more electronegative grabs more electron density from another atom.
The electronegative atom attempts to steal electrons.
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19. Types of Chemical Bonds
Non-Polar Bonds
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20. Non-Polar Bond Joining of atoms with the same electronegativity
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21. Further Insight Into Electronegativity & Chemical Bonds
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22. Introduction
Electrons, of atoms such as oxygen and nitrogen, surrounding the nucleus of an atom, do not evenly distribute themselves evenly but tend to collect in one position.
As a result, the region where electrons are “collected” will be more negative than the rest of the atom.
Atoms with this uneven distribution of charge is said to be polarized.
This allows atoms to be considered electronegative.
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23. Bond Polarity & Chemical Bonds
Bond Polarity is due to differences in electro-negativity
Bond polarity can predict the polarity of a bond
∆EN < 0.4 = non-polar covalent
∆EN between 0.4 and 2.0 = polar covalent
∆EN > 2.0 = ionic
δ used to indicate partial charges
Dipole movement is the measure of a molecule’s overall polarity
μ = Q (charge) * r (distance)
More details to come in Organic Chemistry

24. Pauling Electronegativity Scale

25. Types of Chemical Bonds
Hydrogen Bonds
Sunday, November 18, 2018

26. Hydrogen Bonds
A strong non-bonding interaction that causes a quick, weak “chemical bond.”
Occurs when a hydrogen atom, attached to a highly electronegative atom, interacts with a lone electron from a nearby electronegative atom.
These bonds are broken almost immediately
Depends on temperature.
Sunday, November 18, 2018

27. Hydrogen Bond
Although hydrogen bonds are weak, the vast number of them in large molecules makes them collectively significant
The formation of water in various forms.
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28. Phases of Matter Liquid Solid Gas
Elements and molecules can exist in all three phases
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29. Phases of Matter II
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30. Van der Waals Forces

31. Isomers
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32. Isomers
Isomer
One of two, or more compounds, with the same chemical formula but different structural formula
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33. Isomers II Stereoisomer
Atoms are connected in the same order but have different 3D arrangements
Enantiomer
Stereoisomer that have a mirror-image relationship
Diastereoisomer
Stereoisomer that is not a mirror image.
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34. Isomers III
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35. Isomers IV
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36. Importance of Recognizing Isomers
Sugars
There are different isomers of sugars used in different steps during cell respiration and photosynthesis.
Macromolecule Packets
Hormones & Steroids
Different isomers of hormones, and steroids, are critical to proper development and sexual development.
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37. Isomers of Glucose

38. Isomers of Hormones
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39. Isomers of Hormones II
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