1. Covalent Compounds, Formulas and Naming

2. Covalent Compounds Covalent compounds are compounds formed from 2 or more nonmetals. Examples: H 2 0 (water) CO 2 (carbon dioxide) C 6 H 12 O 6 (glucose) When two nonmetals react, they usually share electrons so that all atoms involved end up with 8 valence electrons (Exception: Hydrogen only needs 2) – it requires less energy for them to share than to donate/receive – because they are only sharing electrons, they do not end up with a charge

3. A covalent bond is a bond that is formed when electrons are shared between atoms – Because this type of bond does not depend on attraction between different charges, covalent bonds are much stronger than ionic bonds Single bond – one pair of electrons shared Double bond – two pairs of electrons shared Triple bond – three pairs of electrons shared Covalent Bonds

4. The names of covalent compounds have prefixes that tell us the number of atoms of each element in the compound: Naming Covalent Compounds Number atoms Prefix 1 2 3 4 5 6 7 8 9 10 mono di tri tetra penta hexa hepta octa nona deca When there is a prefix that ends in an “a” or “o” before oxygen, the “a” or “o” is usually dropped i.e. tetroxide, pentoxide, monoxide

5. Naming Covalent Compounds 1)First you need to identify that the compound is a covalent compound! Compound formed by 2 or more nonmetals Be careful with polyatomic ions! They are covalently bonded, however they have an overall charge so they form ionic compounds!

6. Naming Covalent Compounds 2. If there is more than one atom of the first element, write the appropriate prefix first. If there is only one of the first element, we do not write a prefix 3. Write the name of the first element in the formula using its full name directly after the prefix (they combine to form one word). 4. Write the appropriate prefix for the second element. 5. Write the base name of the second element and change the ending to –ide (like we did for anions in ionic compounds). mono- 1 di- 2 tri- 3 tetra- 4 penta- 5 hexa- 6 hepta- 7 octa- 8 nona- 9 deca- 10 prefix name of 1st element Base name of 2 nd element + “ide” ending

7. Naming Covalent Compounds Practice 1)CO 2 2)N 2 O 3)CCl 4 4)BCl 3 5)SF 6 6)N 2 O 4 carbon dioxide dinitrogen monoxide carbon tetrachloride boron trichloride sulfur hexafluoride dinitrogen tetroxide

8. Writing Formulas for Covalent Compounds 1.Identify that a covalent bond is present 2.Use the prefixes to determine the subscript after each element. DO NOT criss-cross DO NOT reduce the subscripts X subscript

9. Writing Covalent Formulas Practice 1)carbon monoxide 2)disulfur tetrafluoride 3)dichlorine monoxide 4)diiodine pentoxide 5)boron tribromide CO S2F4S2F4 Cl 2 O I2O5I2O5 BBr 3