Transcript Chapter 4.2
Chapter 4.2 Molecular Compounds Naming/Formula Writing Definitions Molecule – two or more elements held together by a covalent bond Covalent bond-a bond between two non-metals that SHARE electrons Covalent bond Properties Soft If they dissolve in water, the solution doesn’t conduct electricity Low melting point Molecular Elements Two or more atoms of the same element are joined together by a covalent bond Ex. S8 Most molecular elements are Diatomic(a molecule made from two atoms) -there are 7 elements that are naturally diatomic: H2, N2, O2, F2, Cl2, Br2, I2 “Hockey stick and puck” of the periodic table These elements simply use the name from the periodic table Rules – Molecular compounds are always NON-METAL + NON-METAL A prefix is always used to indicate the number of atoms of each element in a molecular compound. **Exception: monois never used for the first element Number Prefix 1 Mono 2 Di 3 Tri 4 Tetra 5 penta 6 Hexa 7 Hepta 8 Octa 9 Nona 10 Deca 1. Rules – Molecular compounds are always NON-METAL + NON-METAL 2. Use a prefix then give the name of the first non-metal (except mono) 3. Use a prefix then give the name of the second non-metal and change its ending to -ide Examples – Name the following compounds SO3 P4S10 NF3 CO P2 O 5 Writing the formula of an Ionic compound Rules 1. Follow the name, it will tell you how many atoms of each element you have! Example of formula writing Disulfur pentafluoride Phosphorus trichloride Nitrogen monoxide Common Names Ammonia NH3 Water H2O Ozone O3 Methane CH4 Hydrogen peroxide H2O2 Homework Worksheet “Molecular compounds Naming and Formula Writing”