Writing and Naming Chemical Formulas Six Rules Are The Key……..

Rule 1 The positive ion is always written first in a chemical formula. The positive ion is always written first in a chemical formula. Remember it is the metals on the left side of the periodic table that like to be positive when they become ions. Remember it is the metals on the left side of the periodic table that like to be positive when they become ions. Example: Sodium chloride NaCl Example: Sodium chloride NaCl Example: Calcium chloride CaCl 2 Example: Calcium chloride CaCl 2

Rule 2 The negative ion is written in the second “half” of the formula. The negative ion is written in the second “half” of the formula. Non-metals that have become negative ions change their name to ending with (–ide.) Non-metals that have become negative ions change their name to ending with (–ide.) Example: Sodium chloride NaCl Example: Sodium chloride NaCl Example: magnesium oxide MgO Example: magnesium oxide MgO

Rule 3 Subscripts are used to indicate how many of each ion are needed in the formula to create a neutral compound. Subscripts are used to indicate how many of each ion are needed in the formula to create a neutral compound. Reminder neutral means having no charge value. Reminder neutral means having no charge value. Example: sodium chloride NaCl Example: sodium chloride NaCl Example: calcium flouride CaF 2 Example: calcium flouride CaF 2 Example: aluminum sulfide Al 2 S 3 Example: aluminum sulfide Al 2 S 3

Rule 4 Transition metals are located in the short columns of the Periodic Table. Transition metals are located in the short columns of the Periodic Table. Because these metals often can have more than one possible charge Roman Numerals are used to indicate the charge on the metal. Because these metals often can have more than one possible charge Roman Numerals are used to indicate the charge on the metal. Example: tin IV chloride SnCl 4 Example: tin IV chloride SnCl 4 Example: Chromium VI sulfide CrS 3 Example: Chromium VI sulfide CrS 3

Rule 5 Polyatomic ions are located in an alphabetized list on the back of the Periodic Table. Polyatomic ions are located in an alphabetized list on the back of the Periodic Table. The endings -ate and –ite “mean” mixed with oxygen! The endings -ate and –ite “mean” mixed with oxygen! If a polyatomic ion needs a subscript, the ion must be put in parentheses. If a polyatomic ion needs a subscript, the ion must be put in parentheses. Example: Aluminum hydroxide Al(OH) 3 Example: Aluminum hydroxide Al(OH) 3 Example: Calcium acetate Ca(C 2 H 3 O 2 ) 2 Example: Calcium acetate Ca(C 2 H 3 O 2 ) 2

Rule 6 Two non-metals will sometimes bond covalently. Two non-metals will sometimes bond covalently. Because the charges make “no sense” Latin prefixes are used to indicate how many of each substance are found in the compound. Because the charges make “no sense” Latin prefixes are used to indicate how many of each substance are found in the compound. Example: N 2 O 4 Dinitrogen tetroxide Example: N 2 O 4 Dinitrogen tetroxide Example: triphosphorus hexa- chloride PCl 6 Example: triphosphorus hexa- chloride P 3 Cl 6

Lets Practice! Slide 13 Please write out the following formulas. Please write out the following formulas. Check charges you may need to use subscripts! Check charges you may need to use subscripts! Example: Potassium nitride Example: Potassium nitride Example: Calcium phosphate Example: Calcium phosphate Example: Ammonium oxide Example: Ammonium oxide Example: Gold III chloride Example: Gold III chloride

Lets Practice! Slide 14 Please correctly name the following compounds. Please correctly name the following compounds. Don’t worry these formulas all correctly written with correct subscripts etc…. Don’t worry these formulas all correctly written with correct subscripts etc…. Example: SrCO 3 Example: SrCO 3 Example: Ca(NO 3 ) 2 Example: Ca(NO 3 ) 2 Example: CrO 3 Example: CrO 3 Example: N 2 Cl 4 Example: N 2 Cl 4

More practice………slide 15 Example: MnCl 6 Example: MnCl 6 Example:CCl 4 Example:CCl 4 Example: (NH 4 ) 2 S Example: (NH 4 ) 2 S Example: K 2 CrO 4 Example: K 2 CrO 4 Example: Cr Br 6 Example: Cr Br 6 Example: MgC 2 O 4 Example: MgC 2 O 4

More practice…………slide 16 Example: CO 2 Example: CO 2 Example: CaCO 3 Example: CaCO 3 Example: K 2 SO 4 Example: K 2 SO 4 Example: TiS Example: TiS Example: Li 2 SO 3 Example: Li 2 SO 3 Example: Sr 2 C Example: Sr 2 C

Answers Slide 13 KNO 3 KNO 3 Ca 3 (PO 4 ) 2 Ca 3 (PO 4 ) 2 (NH 4 ) 2 O (NH 4 ) 2 O AuCl 3 AuCl 3

Answers Slide 14 SO 5 SO 5 V 2 S 5 V 2 S 5 Na 2 SO 4 Na 2 SO 4 Fe 2 O 3 Fe 2 O 3 N 3 S 6 N 3 S 6 AlBr 3 AlBr 3

Answers Slide 15 Manganese VI chloride Manganese VI chloride Monocarbon tetrachloride Monocarbon tetrachloride Ammonium sulfide Ammonium sulfide Potassium chromate Potassium chromate Chromium VI bromide Chromium VI bromide Magnesium oxalate Magnesium oxalate

Answers Slide 16 Monocarbon dioxide Monocarbon dioxide Calcium carbonate Calcium carbonate Potassium sulfate Potassium sulfate Titanium II sulfide Titanium II sulfide Lithium sulfite Lithium sulfite Strontium carbide Strontium carbide