Naming Molecules and Writing Molecular Formulas
Dec 13, 2015
Naming Molecules and Writing Molecular Formulas
Naming Binary Molecular Compounds
prefixes tell how many atoms of each element are present
still end with -ide
vowel of the prefix is often dropped
omit prefix mono- for the first element
Greek numerical prefixes.
Number Prefix1 -mono2 -di3 -tri4 -tetra5 -penta6 -hexa7 -hepta8 -octa9 -nona
10 -deca
First to name covalent compounds we need to know some Greek numerical prefixes. It'd be a good idea to memorize these since they will be useful in many other classes.
Writing formulas for binary molecular compounds
write the symbol and use prefixes of each element in order write subscripts for that element
carbon monoxide → CO
nitrogen triiodide → NI3
Naming and Writing Formulas for Acids
acids produce hydrogen ions (H+) when dissolved in water
naming
1. ends in –ide → acid begins with hydro- and ends with –ic
H2S would normally be dihydrogen sulfide
→ acid name is hydrosulfuric acid
2. ends in –ite → only say the anion and it ends in –ous
HNO2 would normally be hydrogen nitrate
→ acid name is nitric acid
3. ends in –ate → only say the anion and it ends in –ic
HMnO4 would normally be hydrogen permanganate
→ acid name is permanganic acid
Writing formulas for acids
reverse the rules for writing names of acids (remember, acids start with hydrogen even if not in the name)
hydrobromic acid → must be hydrogen ion (H1+) and a bromide ion (Br1-). Therefore, is HBr
phosphorous acid → must be hydrogen (H) and phosphite (PO3)3-. Therefore, is H3PO3
Naming and Writing Formulas for Bases an ionic compound that produces hydroxide
ions (OH-) when dissolved in water
Naming
bases are ionic compounds so name like any other ionic compound– just say it!
NaOH is sodium hydroxide
KOH is potassium hydroxide
Formulas
find ionic charges and criss-cross them
aluminum hydroxide contains the ions Al3+ and OH1- and therefore Al(OH)3