Chemical Bonding
Chemical Bonding chemical bond - force holding atoms together in a compound or molecule. Atoms form bonds to gain stability. A “stable” atom has ______ valence electrons (octet rule). Exemptions: H & He (2) and B Atoms will gain, lose, or share electrons to achieve a full octet.
Chemical Bonding Bonded atoms form compounds Chemists use chemical formulas to represent the combination of elements that make up a compound. Examples: NaCl, H2O, C6H12O6 Electron Dot Diagrams can be used to represent how bonding works
Chemical Bonding Three types of bonding: ionic, covalent, and metallic Type depends on what types of elements are being bonded: Metal to metal – metallic Metal to nonmetal – ionic Nonmetal to nonmetal – covalent
Ionic bonding Ionic bonds occur due to a transfer of electrons between atoms Ions result from ionic bonding – cations (+, same name as element) and anions (-, element name with suffix “-ide”) Ionic bonds form ionic compounds The chemical formula for compounds give the simplest ratio of the cations and anions Examples: NaCl, MgBr2, CaO, Mg3N2
Ionic Bonding Electron Dot Diagrams Br Na Cl Mg Br
Covalent Bonding Covalent bonds occur as a result of a sharing of electrons between atoms Since the atoms are sharing the electrons, no ions are formed Covalent bonds form molecular compounds (molecules)
Covalent Bonding Atoms can share more than one pair resulting, so covalent bonds can be single, double, triple or quadruple bonds Chemical formula of molecular compounds gives actual structure of molecule Examples: H2O, CO2, NH3
Covalent Bonding Electron Dot Diagrams H O O C O H
Metallic Bonding Metallic bonding results from nuclei of metal atoms existing in an area of free-flowing, delocalized electrons (often called a “sea of electrons”)
Metallic Bonding The sea of electrons produce some of the properties of metals Conduction of electricity (electrons can flow) Malleability Ductile Alloy – mixture of metals Alloys often have superior properties to those of the metals that make them up