Naming Chemical Compounds

ReviewWhat is a chemical formula?

• shorthand representation of the composition of a substance using atomic symbols and numerical subscripts

ReviewWhat 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)

ReviewSignificance 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)

ReviewSignificance 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.

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

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

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)

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!!!)

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

Naming Ionic Compounds

Prefixes:

1: mono-

2: di-

3: tri-

4: tetra-

5: penta-

6: hexa-

7: hepta-

8: octa-

9: nona-

10: deca-

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

Naming Ionic Compounds

Want more help? Try watching the video at https://youtu.be/TQKIbJIqLeA.

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

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-

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

Naming Molecular Compounds

Acids

• when in water, produce H+ ions, name usually from characteristic anion

• Hydro acids: hydro + name of halogen + -ic + acid

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

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)

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

Naming Molecular Compounds

Want more help? Try watching the video at https://youtu.be/VokWJy_jpAc.

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…

Has a metal?

No

NoNo

NoNo

Yes

YesYes

Yes

Yes

Has hydrogen in the formula? Has only two elements?

binary molecularcompound

Has oxygen?

hydroacid oxoacid

binary ioniccompound

Has H2O in theformula?

polyatomic ioniccompound

hydrate

Writing Formulas

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

Writing Formulas

Examples:• Fe3+ + Cl1- becomes

• Al3+ + O2- becomes

• Sn2+ + O2- becomes

• Mg2+ + (OH)1- becomes

• NH41+ + SO4

2- becomes

• FeCl3

• Al2O3

• SnO

• Mg(OH)2

• (NH4)2SO4

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)