22.3 Notes Continued Part C

Objectives Write formulas and names for covalent compounds

Covalent compounds Made of just nonmetals Share electrons Smallest piece is a molecule Can’t be held together because of opposite charges Can’t use charges to figure out how many of each atom

Covalent/Molecular compounds Ionic compounds use charges to determine how many of each element. Molecular compounds name tells you the number of atoms. Uses prefixes to tell you the number

Naming Covalent Compounds Prefix element name Prefix element name-ide The last vowel of the prefix is dropped when the second element begins with a vowel as in pentoxide No double vowels when writing names (oa oo) Often the prefix mono- is omitted from the first element when naming Many times it is also omitted from 2nd element, though it is used for emphasis in some cases

Examples Carbon dioxide – CO2 Dihydrogen monoxide – H2O Dinitrogren pentasulfide – N2S5 Tricarbon tetrafluoride – C3F4

Name These N2O NO2 Cl4O7 NBr3 BaCl5

Writing formulas for Covalent Compounds Simply write the chemical symbol Subscript is derived from the prefix Mono = 1, di = 2, tri = 3, ect

Write formulas for these diphosphorus pentoxide tetraiodide nonoxide sulfur hexaflouride Carbon tetrahydride phosphorus trifluoride

Hydrates An ionic compound that has water chemically attached to its ions and written into its chemical formula Some ionic compounds have water molecules as part of their structure

Hydrates pg. 708 These same prefixes are used when naming the hydrates previously discussed. The main ionic compound is named the regular way, but the number of water molecules in the hydrate is indicated by the Greek prefix. Chemical formula • # H2O

In-Class Assignment/Homework Finish naming Molecular Compounds WKT 22.3 Reinforcement WKT