Bonding and Forces

Chemical Bonds What is a chemical bond? An attraction between 2 or more atoms that allows us to create new substances 2 types of chemical bonds Ionic Covalent

Ionic Bonds Ionic bond A force that holds ions together in an ionic compound One element takes electrons from another element Can be broken easily by water Form crystalline solids Solids that have a pattern in which the ions are arranged

Covalent Bonds Covalent Bond A physical bond made when 2 or more elements share electrons with each other Each line drawn represents 2 electrons H---H (the hydrogens are sharing 2 electrons) Different amounts of lines represent different types of bonds 1 line Sharing 2 electrons A single bond 2 lines Sharing 4 electrons A double bond 3 lines Sharing 6 electrons A triple bond

Covalent Bonds 2 types of covalent bonds Polar covalent bonds When the sharing of the electrons is unequal Nonpolar covalent bonds When the sharing of the electrons is equal

Polar Covalent Nonpolar Covalent Examples H2O NH3 CO Acids HCl HI HBr Examples N---N F---F H---H O---C---O CH4

How Do We Know What Bond Forms? Based on electronegativity The ability of an element to attract electrons when the atom is in a compound The Rules of Predicting the Bonds If the difference in electronegativity is 0-0.5 Nonpolar covalent If the difference in electronegativity is 0.6-1.5 Polar covalent If the difference in electronegativity is 1.6-higher Ionic bond In general Increase from top to bottom in a group Increase from left to right across a period

You Try NaBr CO2 NH3 HI Cl2 C6H6 MgS

Forces and Bonding are Related 4 types of forces London dispersion Weakest force found in ALL compounds/molecules ALWAYS PRESENT NO MATTER THE MOLECULE Dipole-Dipole Where a slight charge of a molecule is attracted to another slight charge of a different molecule Present in polar covalent bonds that do not have Hydrogen with Fluorine, Oxygen, or Nitrogen Hydrogen Bonding Present in polar covalent bonds Only when there is hydrogen with fluorine, oxygen, or nitrogen Ionic Forces Just ionic bonds

You Try H2O C2H6 HF Cu2O CH3F CH3OH Br2