Covalent Bonding Electron Sharing

Covalent bonds result from the sharing of e- Ionic bonds result from the transfer of e-

Properties of Covalent Compounds Made of 2 nonmetals Low melting points Low boiling points Soft and squishy More flammable than ionic compounds Do not conduct electricity in water Are not usually very soluble in water

Molecular Orbitals Shared space electrons move in Created when 2 atomic orbitals overlap

Energy Atoms want the lowest potential energy possible because it is more stable As 2 atoms come together their potential energy decreases When energy at lowest point bond forms Attractive and repulsive forces are balanced

Bond Length Bond length is the average distance between the nuclei of the atoms at lowest potential energy Its like the atoms are held together by a slinky The atoms are constantly vibrating so the distance actually changes slightly

Bond Energy The amount of energy required to break the bonds in 1 mol of a chemical compound Higher bond energy means stronger bonds Higher bond energy means shorter bond length

Kinds of Covalent Bonds 2 types: Polar covalent -the electrons are not shared equally Nonpolar covalent- electrons are shared equally Polar have more ionic character than nonpolar

What kind of Bond? 0-0.5 make nonpolar covalent bonds The difference in electronegativity of the 2 elements determines kind of bond Differences of: 0-0.5 make nonpolar covalent bonds 0.6-2.1 make polar covalent 2.2-3.3 make ionic bonds Electronegativity difference is not the only way to determine the type of bond, you must also look at the properties of the compound

nonPOLAR Covalent Bonds Electrons equally shared between the atoms No ionic character

Polar Covalent Bonds Ends that have partial + and – charges Electrons spend more time around the atom with the larger electronegativity Called dipole molecules Not ionic because electrons still being shared Larger polarity (larger difference in electronegativity) means stronger bond (higher bond energy) and shorter bond length More polar has more ionic character Bonds

Metallic Bonding Valence electrons attracted to all the other atoms in the sample Electrons move freely throughout the sample Allows the conduction of electricity “sea of electrons”