chapters 4 & 5 – formation of compounds naming compounds and writing formulas
TRANSCRIPT
CompoundName of Metal cation(first element)
Name of non metal anion (second element)
Name of compound
Na2O Sodium ion Na1+ Oxide ion O2- Sodium oxide
KF
BaCl2
Al2S3
Ca3N2
LiBr
Naming Ionic Compounds
1. Name the metal first (cation)– The cation name simply is the name of the
element
2. Name the non-metal next (anion)– Anion name is non-metal name with –ide
suffix (oxygen oxide)
Writing Ionic Formulas
1. Write the symbol for the metal first with the charge
2. Write the symbol for the nonmetal next with the charge
3. Crisscross the number of the charge
4. All compounds are neutral, so the charges must add to ZERO
Naming when the metal forms more than one charge
Look at the Periodic Table – some elements have more than one charge – Transition Metals
Ex: Copper +1 or +2
• Roman Numerals are used to indicate the charge.
Copper (I) or Copper (II)
Cu+1 or Cu+2
Naming
• Determine the charge by working backwards
• Write the charge in roman numerals in the name
CuF2
• Copper is either +1 or +2 charge• In this case it is +2 since there are two Fluorine
atoms for every one copper (F is always -1 charge)• Copper (II) Fluoride
Metal + Polyatomic
• Polyatomic Ion – Groups of nonmetal atoms bonded together that carry a charge.
• Always include parenthesis around these ions
• End in –ate or –ite– Exceptions – Hydroxide, Cyanide, Ammonium
• Found on the back of your periodic table
Naming
• Metal bonded to a polyatomic ion Al2(SO4)3
– Name the metal– Name the polyatomic ion as it appears on the
back of your periodic table
Writing
• Write the symbol for the metal and charge
• Write the polyatomic ion in parenthesis and with charge
• Criss cross the charges
Naming Molecular Compounds
• Two non-metals bonded together; shared bond of electronsExample: CO2 = carbon dioxide
• Prefixes are used to express the number of each element
• The second nonmetal ends in –ide
• Never reduce
Prefixes
• (1) mono, (2) di, (3) tri, (4) tetra,
(5) penta, (6) hexa, (7) hepta,
(8) octa, (9) nona, (10) deca
• The prefix mono- is not used with the first named element
Use the back of your periodic table to help you