Naming Chemical Compounds

1. Naming Chemical Compounds

2. Review What is a chemical formula? • shorthand representation of the composition of a substance using atomic symbols and numerical subscripts • can represent a molecule (covalent bonded structure) or a formula unit (ionic bonded structure)

3. Review Significance of a chemical formula • formula tells number and type of atoms in a molecule or formula unit (one atom difference can cause change in properties) • Examples: Ag, NaCl, HCl, Al2(SO4)3, CaSO4 5 H2O, etc.

4. Naming Ionic Compounds Binary ionic compounds • Metal named first • Name of non-metal has –ide added • If metal has more than one possible charge use stock system (Roman numerals) or common name Ex: NaCl, KI, FeF2, FeF3

5. Naming Ionic Compounds Compounds with polyatomic ions • Cation is named first (using stock or common name) • Anion is named second (using name of polyatomic ion) Al2(CO3)3, BaSO4, CaSO3, Fe(NO3)2, NH4Cl (DO NOT change endings of polyatomic ions!!!)

6. Naming Ionic Compounds Hydrates • ionic compounds that absorb water into their structures • named like regular ionic compounds, add numeric prefix and hydrate at the end

7. Naming Ionic Compounds Prefixes: 1: mono- 2: di- 3: tri- 4: tetra- 5: penta- 6: hexa- 7: hepta- 8: octa- 9: nona- 10: deca-

8. Naming Ionic Compounds Hydrates • ionic compounds that absorb water into their structures • named like regular ionic compounds, add numeric prefix and hydrate at the end MgSO4 7 H2O, CuSO4 5 H2O

9. Naming Molecular Compounds Binary molecular compounds • Element from left-most part of table is named first • Name of second element has –ide added • Use Greek prefixes to indicate number of atoms

10. Naming Molecular Compounds Prefixes: 1: *mono- (*only with second element) 2: di- 3: tri- 4: tetra- 5: penta- 6: hexa- 7: hepta- 8: octa- 9: nona- 10: deca-

11. Naming Molecular Compounds Binary molecular compounds • Element from left-most part of table is named first • Name of second element has –ide added • Use Greek prefixes to indicate number of atoms CO, CCl4, N2O, N2O3

12. Naming Molecular Compounds Acids • when in water, produce H+ ions, name usually from characteristic anion • Hydro acids: hydro + name of halogen + -ic + acid HCl, HF, HBr • Oxoacids: polyatomic ion + acid (use –ous and –ic as needed, -ic goes with > # O atoms) H2SO4, HNO2, HNO3

13. Naming Chemical Compounds Given: Chemical Formula Wanted: Name of Compound • Need to ask questions to determine which naming rules to use • Here is one set of questions you could use…

14. Yes No Has a metal? No Yes No Yes Yes No Yes No

15. Writing Formulas • Use the criss-cross method – the charges (superscripts) go to the bottom (as subscripts) and switch from right to left

16. Writing Formulas Examples: • Fe3+ + Cl1- becomes • Al3+ + O2- becomes • Sn2+ + O2- becomes • Mg2+ + (OH)1- becomes • NH41+ + SO42- becomes • FeCl3 • Al2O3 • SnO • Mg(OH)2 • (NH4)2SO4

17. Writing Formulas • Remember: you are looking for the smallest whole-number ratio of ions that will give an overall charge of 0 – that’s why the 3rd example has no subscripts (2+ +2- = 0)