Compounds
Ionic Compounds
(Page 7 in notes….we skipped it intentionally last day)

All are solids at SATP (Standard Ambient
Temperature and Pressure) of 25oC and 100 kPa.

When they dissolve in water, they form aqueous
solutions that:
 are
colored or colorless
 conduct
electricity ie. they are electrolytes
(show examples)
Ionic Compounds

These compounds form after an electron
transfer:
 usually
from a metal to a nonmetal
 the
resulting ions (cations and anions) are
attracted to each other (since they are
oppositely charged) and they form ionic bonds
Start to draw Sodium chloride example on board. Stop before
writing compound
Ionic Compounds

Together all of the ions present form an ionic
crystal lattice in which the net charge is zero
Ionic Compounds

Eg: (1) in a sample of sodium chloride, NaCl, for
every Na+ ion there is one Cl- ion

Eg (2) in a sample of calclium chloride, CaCl2, for
every Ca2+ ion there are 2 Cl- ions
Formula Unit: an expression of the simplest whole
number ratio of cations to anions
Complete Examples on Board
(Sodium Chloride and Calcium Chloride) extra page?
Writing Empirical Formulas for Ionic
Compounds (Page 8)

Empirical formulas show the ratios of different ions
found in an ionic compound.
Example:
Compound: KCl (Potassium Chloride)
Ratio: one K+ : one ClEmperical Formula: K1Cl1 is the same as KCl
Even though a sample of potassium chloride has trillions
and trillions each ion, we write the formula as the smallest
possible ratio, which is 1:1
General Rules (of writing formulas)
Write each ion symbol with charge.
2. Determine # of +ve and –ve ions needed to create a
compound with a balanced charge.
Total positive charge = total negative charge.
1.
3.
Assign subscripts to each ion

4.
(subscript indicates the number of that ion present in
the formula).
Re-write the symbol of each ion with subscript. Do not
include ion charges in final formula.
Writing Empirical Formulas for Ionic
Compounds

Heed the Note section on the top of page 9
Examples:
Monatomic: Silver chloride and Aluminum Oxide
Polyatomic: Potassium carbonate and ammonium nitrate
Multivalent: Iron(II) sulfide and Lead(IV) oxide
Hydrate: Zinc chloride hexahydrate and
Copper(II)sulphate pentahydrate
Worksheets 8-11

Complete the first half of
each section before
completely finishing any
worksheet!

This is so you encounter a
variety of problems now
while I can help you.
Quiz #1