1. Writing & Naming Formulas of
Ionic & Covalent Compounds

2. Review of the Periodic Table Periods = number of e- energy levels.
Groups (families) = the number of valence electrons (A - groups) IA
VIIIA 1
IIA
IIIA IVA VA
VIA VIIA 2 3
Transition Metals 4 5 6 7

3. Metals Metalloids Nonmetals
Types of Compounds:
Ionic = Metal + Nonmetal
Covalent = 2 Nometals or Metalloid & Nonmetal
Metals Metalloids Nonmetals
IA VIIIA
IIA IIIA IVA VA VIA VIIA
Transition Metals 1 2 3 4 5 6 7 6 7

4. Eight valence electrons. Chemically stable.
Chemical Compounds
An atom consist of a positively charged nucleus (protons and neutrons) and orbiting electrons.
Very
Important!
Atoms of elements are not chemically stable until they have 8 valence electrons (octet rule).
Atoms gain, lose or share electrons with other atoms to be come chemically stable ( have 8 valence electrons ). -2
Six valence electrons.
Not chemically
Eight valence electrons. Chemically stable. 8+ 8+
stable.
Oxygen Atom
Oxide Ion

5. Two Types of Compounds
I o n i c - occurs when a metal loses all its valence electrons to a nonmetal. The metal becomes a cation (+ion), while the nonmetal becomes an anion (- ion).
C o v a l e n t - two nonmetals share electrons. Neither loses or gains electrons - they share electrons. Neither atom becomes an ion.

6. Ionic Compounds
Crystalline Lattice

7. + + Burning Magnesium 2Mg + O 2 → 2MgO
Opposite charges hold the compound together. +2 + -2 +
12+ 8+
12+ 8+
Magnesium Atom + Oxygen Atom ➝
Magnesium Ion
Oxide Ion +

8. + + 2Na + Cl 2 → 2NaCl Formation of Sodium Chloride -
Opposite charges hold the compound together. - + + +
11+
17+
11+
17+
Sodium Atom
Chlorine Atom
Sodium Ion
Chloride Ion + ➝ +

9. Ionic Compounds Contain a metal and a nonmetal.
The Metal loses e- and becomes a cation (+).
The Nonmetal gains e- and becomes an anion(-).
Metal is listed first, followed by nonmetal.
Change the name of the nonmetal to -ide.
Examples: nitride, sulfide, fluoride, oxide, bromide, iodide, chloride, phosphide.

10. Valence (Oxidation Number)
The valence of an elements is the charge an atom takes when it loses or gains electrons and becomes an ion.
Metal atoms lose 1, 2 or 3 electrons and become + ions (cations) Nonmetals gain 1,2 or 3 electrons and become - ions (anions)
+1 0
Transition Metals
Multiple valences

11. The 5 Steps for writing an ionic compound formula:
(1)Write the symbols of the two elements. (2)Write the valence of each as superscripts. (3)Drop the positive and negative signs. (4)Crisscross the superscripts so they
become subscripts.
(5)Reduce when possible.

12. Formula for boron oxide
1. Write the symbols of the two elements.
B O

13. Formula for boron oxide
2. Write the valence for each element.
B O

14. Formula for boron oxide
3. Drop the positive & negative sign. -2 3
B O

15. Formula for boron oxide
4. Crisscross the superscripts so they become subscripts.
3 2
B O

16. Formula for boron oxide
4. Crisscross the superscripts so they become subscripts.
B 2 O

17. Formula for boron oxide
5. Reduce subscripts when possible. (not possible here) B 2 O

18. S r 2O 2 Al 3 P3 Pb2O 4 Ba 3P 2 S r O AlP PbO2 Examples of Reduction
of Subscripts:
S r 2O Al P3 Pb2O Ba 3P
S r O AlP PbO2
Doesn’t Reduce
Reduces to
Reduces to
Reduces to
Reduces to 20

19. Mn+6 Fe+3 Cu+2 Fe+2 Cu+1 Most Transition metals have two valences.
Roman numerals are used in the name of the transition metal in the compound
to show the valence on the cation.
Period 4 Transition Metals Sc TI V Cr Mn Fe Co Ni Cu Zn +3 +4 +5 +6 +2 +1
Examples:
Mn+6 Fe+3 Cu+2
Manganese(VI) Iron(III) Copper(II)
Mn+4 Manganese(IV)
Fe+2
Iron(II)
Cu+1
Copper(I)
index 21

20. Examples of Transition Metals
Iron(II) Fe +2
Iron(III) Fe +3
Copper(I) Cu+1
Copper(II)Cu+2 Manganese(II) Mn+2 Manganese(IV)Mn+4
index

21. Naming binary compounds containing
a transition metal.
Silver(I) chloride Copper(II) phosphide
formula
Fe2 O3
ZnCl 2 AgCl Cu 3 P2
name
Iron(III) oxide
Zinc(II) chloride
PbS2 MnO2
Lead(IV) sulfide
Manganese(IV) oxide

22. Polyatomic Ions -1 hydroxide
Polyatomic (many atom) ions are covalent molecules with a charge. They behave as if they were a one-atom ion.

23. Polyatomic Ions NH +1 Ammonium Hydroxide NO 2 Nitrite NO 3 Nitrate
SO Sulfite SO4 Sulfate CO3 Carbonate
PO4 Phosphate -2 4 -1 -2 OH -1 -2 -1 -3
Note: Ammonium is the only polyatomic ion with a + charge. Treat polyatomic ions as you would any ion - crisscross to determine the formula. The only difference is that when you have more than one of a specific polyatomic ion in a formula you must encase it in parenthesis.

24. Writing Ternary Formulas
(Ternary compounds have 3 elements in them.)
Cation
Anion
Compound +2
NO -1 3
Ca(NO3)2
Mg +2
PO -3 4
Mg 3(PO4)2
Ba+2
OH -1
Ba(OH)2 -2
SO4
Ba SO4 Ca
As in all ionic compounds you must reduce subscripts, but you cannot change the formula of the polyatomic ion. You can only reduce subscripts outside the parenthesis.

25. Compounds with Polyatomic ions-2
Carbonate CO 3
Sodium carbonate Na2CO3 Calcium carbonate Ca CO 3 Aluminum carbonate Al2(CO 3)3
Phosphate PO4 -3
Sodium phosphate Na3PO4 Calcium phosphate Ca3(PO3 )2 Aluminum phosphate AlPO3

26. Covalent Compounds Water Molecule Hydrogen Atom Oxygen Atom

27. Covalent Compounds
Two nonmetals share electrons so both have 8 valence electrons. Exception: H
Neither takes on a charge - no valence. Do not crisscross to determine formula.
Must use prefixes in the name.
Name tells you the formula. Example: N2O4 is dinitrogen tetroxide.
You cannot reduce the formulas!!!

28. + 2H2 + O2 → 2H2O Reaction between hydrogen + oxygen 1+ 8+ 1+ 1+ 8+ 1+
1+ 1+ 8+ 1+
2 Hydrogen Atoms
Oxygen Atom
Water Molecule

29. A prefix tells you the number of atoms of that element
Covalent Prefixes
Mon - 1
Di - 2
Tri - 3
Tetra - 4
Pent - 5
Hex - 6
A prefix tells you the number of atoms of that element
in the compound.

30. N2O3 CH4 PO5 S2F3 Naming Covalent Compounds
Dinitrogen trioxide Carbon tetrahydride Phosphorus pentoxide disulfur trifluoride
N2O3 CH4 PO5 S2F3

31. Ionic and Covalent Structure
Ionic compounds form a crystalline lattice - a repeating pattern of ions.
Water
H atoms
O atom
Covalent compounds form individual molecules that are not connected to each other. +3
B ions
N-3
ions
Boron nitride

32. Naming Binary Compounds
Does the compound have a metal?
Yes No
Ionic
Covalent
(Two Nonmetals)
(Metal cation + Nonmetal anion)
Place metal first followed by nonmetal ending in -ide
Contain a Transition Metal?
Place the nonmetal furthest to the left on the periodic table first, then the other nonmetal ending in -ide.
Yes Use Roman No
Do not use Roman Numerals
Examples: sodium chloride magnesium nitride aluminum fluoride beryllium oxide
Use prefixes to tell the number of atoms in the compound
mon(o)-1, di-2, tri-3, tetr(a)-4, pent(a)-5, hex-6
Examples:
dinitrogen trioxide, nitrogen trichloride, phosphorus pentoxide, sulfur dioxide carbon tetrachloride, dihydrogen oxide
Numerals to tell the valence of the metal. Examples:
iron(III) oxide copper(II) chloride manganese(IV) oxide silver(I) chloride

33. CoF2 PCl3 Sr3N2 KOH NH3 Name these compounds: cobalt(II) fluoride
phorphorus trichloride
strontium nitride
potassium hydroxide nitrogen trihydride

34. Zn3N2 LiBr N2O5 MnS2 H2O Write formulas for these compounds:
zinc(II) nitride
lithium bromide
dinitrogen pentoxide
manganese(IV) sulfide dihydrogen oxide

35. Summing up: Ionic
Ionic bonding occurs between a metal and a nonmetal. Metals lose all their valence e- and become cations. Nonmetals gain enough e- to fill their valence level and become anions.
Always crisscross valences and reduce to determine the formulas of ionic compounds
Do not use prefixes in the names. Ions form a crystalline lattice.

36. Summing up: Covalent
Covalent bonding occurs when two nonmetals share electrons to fill their valence energy level.
Never use valence to determine the formula - there isn’t any valence. Since the two atoms share electrons, they do not take on a charge.
Always use prefixes in the names.
Atoms combine to form individual molecules.

37. Chemical Formulas Index
Types of Compounds
Ionic Compounds Covalent Compounds
Valence Covalent Prefixes
Transition Metals Steps in Writing
a Formula
Polyatomic Ions
Lattice & Molecules
Naming Flowchart Polar Molecules
Summing Up

38. Credits
© Douglas Gilliland The Physical Science Series