Chemical Bonding Chp 7.1-7.2, 7.3, 8.1

A chemical bond is a force that holds two atoms together. Bonding Basics A chemical bond is a force that holds two atoms together. Valence electrons are involved in the formation of chemical bonds between two atoms. Octet Rule-atoms are stable with eight valence electrons in the outer energy level. (except H and He) Elements tend to react to acquire the stable electron configuration of an unreactive noble gas: ns2p6

ionic covalent metallic Starts with a metal atom Ends with a nonmetal atom Starts with a nonmetal atom You have a metal from the periodic table

Ionic Bonding Review: Electronegativity is the ability to attract and pull on electrons. A metal atom with very low electronegativity comes in contact with a nonmetal atom that has a very high electronegativity. Therefore the nonmetal will pull the electron away from the metal. A cation forms when metal atom loses one or more valence electrons to attain a noble gas configuration. Groups 1 and 2 metals are the most reactive because it is easy to lose 1 or 2 valence electrons. A anion forms when a nonmetal atom gains one or more valence electrons to attain a noble gas configuration. Group 6 and 6 are the most reactive because it is easy to gain 1 or 2 valence electrons. Electrostatic force bonds the ions together

Covalent Bonding Sharing is Caring! Nonmetal atoms of similar electronegativity combine to form a covalent bond: “sharing” of electrons. If the sharing of the electrons in the bond is “equal” then a nonpolar covalent bond forms. Diatomic elements! Electrons are equally shared. Both atoms have the same pull on the electrons. 7 Diatomic Elements: H2, N2, O2, F2, Cl2, Br2, I2 If the sharing of the electrons in the bond is “unequal” then a polar covalent bond forms. Two different nonmetals! Electrons are unequally shared. One atom has a greater pull on the electrons. everages

In a covalent bond, the net attraction between positive nucleus and negative electrons is greater than the net repulsion between 2 electrons or 2 nuclei.

Metallic Bonding For metal atoms, the electrons are not tied to a specific nucleus so they are free to move creating a model that looks like an array of positive nuclei surrounded in a sea of electrons. It is important to understand that we use the term metallic bonding and not metallic bond. The bonding in metals is collective and not a single bond between one metal atom and another metal atom. A metallic bonding is the attraction of metal cations for delocalized electrons. https://www.youtube.com/watch?v=6AQHO1Y5Gdo