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

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. Sunday, November 18, 2018

Molecules Chemical Formulas Sunday, November 18, 2018

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 11/18/2018 4:50:15 PM

Formulas in Biology II Sunday, November 18, 2018

Types of Chemical Bonds Covalent Bond Ionic Bond Hydrogen Bond Polar Bond Non-polar Bond 11/18/2018 4:50:15 PM

Types of Chemical Bonds Covalent Bonds Sunday, November 18, 2018

Covalent Bonds I A bond in which electrons are shared. Resulting in an compound more stable than the individual atoms Sunday, November 18, 2018

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 Sunday, November 18, 2018

Types of Covalent Bonds II Sunday, November 18, 2018

Types of Covalent Bonds III Sunday, November 18, 2018

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. Sunday, November 18, 2018

Saturated vs. Unsaturated Unsaturated molecules allow the formation of kinks. Kinks prevent fat molecules from sticking together. Sunday, November 18, 2018

Types of Chemical Bonds Ionic Bonds Sunday, November 18, 2018

Ionic Bond A bond that is formed by the attraction of two ions (cation & anion) of opposite charge Cation Positive charge Anion Negative charge Sunday, November 18, 2018

Ionic Bonds II Sunday, November 18, 2018

Types of Chemical Bonds Polar Bond Sunday, November 18, 2018

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. Sunday, November 18, 2018

Types of Chemical Bonds Non-Polar Bonds Sunday, November 18, 2018

Non-Polar Bond Joining of atoms with the same electronegativity Sunday, November 18, 2018

Further Insight Into Electronegativity & Chemical Bonds Sunday, November 18, 2018

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. 11/18/2018 4:50:15 PM

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

Pauling Electronegativity Scale

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

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

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. 11/18/2018 4:50:16 PM

Phases of Matter Liquid Solid Gas Elements and molecules can exist in all three phases Sunday, November 18, 2018

Phases of Matter II Sunday, November 18, 2018

Van der Waals Forces

Isomers Sunday, November 18, 2018

Isomers Isomer One of two, or more compounds, with the same chemical formula but different structural formula Sunday, November 18, 2018

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. Sunday, November 18, 2018

Isomers III Sunday, November 18, 2018

Isomers IV Sunday, November 18, 2018

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. 11/18/2018 4:50:16 PM

Isomers of Glucose

Isomers of Hormones Sunday, November 18, 2018

Isomers of Hormones II Sunday, November 18, 2018