ION QUIZ
Today you will need your periodic table/ion sheet and your packet
Warmup (3 minutes)
1. What is a valence electron?2. Draw the Lewis dot structures of
magnesium and fluorine.3. What does the term “neutral” mean
(in terms of math and science)?
Is the red guy a cation or an anion?
Is the red guy a metal or a nonmetal?
Chemistry puts the "cation" in education. What's a cation afraid of?
A dogion!
Metal atoms lose e- to form positive ions called cations:
K+
Ca 2+
NH4+
Nonmetal atoms gain e- to form negative ions called anions:
Cl-
S2-
CO32-
Mg2+
Superscript written to the upper right shows the charge
F-
If the charge is +1 or -1, you don’t have to include the “1”
Called an “oxidation number”
Ion: An atom (or group of atoms) that has lost or gained e- to follow the Octet Rule and is now electrically charged
IonizationF + e- F-
Neutral but unstable fluorine atom, F
Write the (oxidation) equation showing how magnesium becomes an ion
Same # electrons as neon, but NOT an atom of neon!
Mg Mg2+ + 2e-
Same # e- as…which element?
Write the (reduction) equation showing how flourine becomes an ion
1A metals: +1 ions 2A metals: +2 ions
7A nonmetals: -1 ions 6A nonmetals: -2 ions
What patterns do you see? Are there any exceptions to
these patterns?
Special ions(refer to handout)
Some transition metals lose different numbers of electrons when they become ions
They can have different charges as a cation, and must be written with roman numerals representing their charge (exception: Al3+)
Examples?
Polyatomic ions: group of more than one atoms with a charge (+ or -)
Example: Why do chemists like nitrates so much?
They're cheaper than day rates.
Nonmetal atoms remove e- from metal atoms.
Ionic Bonds
The two atoms become oppositely charged ions that attract each other, resulting in an ionic bond. An ionic compound forms.
Na+
Cl-
Read through EX 1 on “Writing and Naming Ionic Compounds” Handout that shows the crisscross method.
EX 2: Write the formula for the ionic compound calcium oxideStep 1: Write each ion with the correct charge. Look at periodic table group or cheat sheet for help. Ca2+ O2-
Step 2: “Criss-cross” number associated with each charge (do not include the + or -) Ca2O2
Step 3: Remove any subscripts of 1. Eliminate both subscripts if they are the same. Write the formula.CaO
EX 3: Write the formula for the ionic compound aluminum carbonate
Al3+ CO32-
Al2CO33 ????
Al2(CO3)3
another example: iron(II)phosphateFe2+ PO4
3-
Fe2(PO4)3 NOOOOOOO!
Fe3(PO4)2
Fe 2+ PO43-
Fe 2+
Fe 2+
PO43-
Fe 2+
PO43-
Fe 2+
Fe 2+
PO43-
Fe 2+
PO43-
Fe 2+Fe 2+
PO43-
6+6-
Ionic compounds aren’t present as individual molecules, they exist as large crystals with many many of the same ions. The subscripts show the RATIOS of the two ions --- one formula unit of this compound has 3 iron(II)’s and 2 phosphates.
3:2 is simplified from 6:4
or 30,000:20,000
Name Formula
potassium nitride
copper (I) bromide
potassium phosphide
magnesium fluoride
K3N
CuBr
K3P
MgF2
Name these 2 compounds:CoSa.Figure out which ions
form the compound because the ion charge could be important.
Since S forms S2-, Co must be Co2+
b. Name the ions, cation first, then anion
c. Change ending to –ide if it’s a pure element.
cobalt (II)sulfide
d. Transition metals always get a roman numeral to indicate their charge!
Na2SO3
sodium sulfiteCommon mistakes:sodium(II)sulfitesodium(I)sulfitesodium sulfide/sulfate
Formula NameNa2O
CuS
LiBr
CuCl
Sodium Oxide
Copper (II) Sulfide
Lithium Bromide
Copper (I) Chloride
Name Formula
Ammonium Phosphate
Iron (II) Nitrate
Sodium Sulfate
Silver Acetate
(NH4)3PO4
Fe(NO3)2
Na2SO4
AgC2H3O2
Formula NameFe(OH)3
Mg(NO2)2
NiCO3
Cd(HCO3)2
Iron (III) Hydroxide
Magnesium Nitrite
Nickel (II) Carbonate
Cadmium (II) hydrogen carbonate
orCadmium (II) bicarbonate
Name FormulaSodium Dichromate
Tin (II) Chromate
Magnesium Permanganate
lead (IV) bisulfate
Na2Cr2O7
SnCrO4
Mg(MnO4)2
Pb(HSO4)4
Work on your packet!
Make sure you have the Precipitation Lab with you
next class!
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