chapter 5: ions and ionic compounds

Ion: an atom or group of atoms that has a charge as a result of losing or gaining one or more electrons

Ca+ion: positively charged ion

Formed from a metal atom losing electrons

Anion: negatively charged ion

Formed from a nonmetal atom gaining electrons

+1 0-1-2

-3+/- 4

+2

+3

Metals can have various charges, so you MUST specify which one you have!

The charge of a metal is indicated by a Roman Numeral.

Exceptions: Groups 1 & 2, Silver (Ag), and Zinc (Zn) have only one charge, so they do not get Roman numerals in their names!

Examples:1.) Copper (II) = Cu+2

2.) Iron (III) = Fe+2

Name the following transition metal ions:1.) Cr+2

2.) Cr+3

3.) Mn+2

4.) Mn+3

5.) Pt+2

6.) Pt+4

Name the following transition metal ions:1.) Cr+2 Chromium (II)2.) Cr+3 Chromium (III)3.) Mn+2 Manganese (II)4.) Mn+3 Manganese (III)5.) Pt+2 Platinum (II)6.) Pt+4 Platinum (IV)

Determine if the following ions are cations (metal) or anions (nonmetal):

1.) Calcium ion2.) Nitrogen ion3.) Potassium ion4.) Bromine ion5.) Oxygen ion6.) Lead (IV) ion

Determine if the following ions are cations or anions:

1.) Calcium ion: cation2.) Nitrogen ion: anion3.) Potassium ion: cation4.) Bromine ion: anion5.) Oxygen ion: anion6.) Lead (IV) ion: cation

Element Symbol and Charg

e

Metal or Nonmeta

l?

Anion or

Cation?

Sodium Na+1 Metal CationFluorine

Magnesium

Copper (II)

Element Symbol and Charg

e

Metal or Nonmeta

l?

Anion or

Cation?

Sodium Na+1 Metal CationFluorine F-1 Nonmetal Anion

Magnesium

Mg+2 Metal Cation

Copper (II) Cu+2 Metal Cation

Ion # of protons

# of electrons

S-2

Al+3

Fe+2

N-3

Ca+2

C-4

Ion # of protons

# of electrons

S-2 16 18Al+3 13 10Fe+2 26 24N-3 7 10

Ca+2 20 18C-4 6 10

Ion # of protons

# of electrons

Na+1

O-2

Zn+2

F-1

Mg+2

P-3

Ion # of protons

# of electrons

Na+1 11 10O-2 8 10

Zn+2 30 28F-1 9 10

Mg+2 12 10P-3 15 18

Octet Rule: Atoms lose or gain electrons to match the valence electron configuration of a noble gas.

Atoms gain or lose electrons because they want to be more stable.

Full valence shells = stable atoms

1.) Determine number of electrons2.) Write electron configuration

Example: Fluorine ion = F-1

Fluorine ion has 10 electronsElectron configuration is 1s22s22p6

Neon also has 10 electrons and has the same electron configuration, so F-1 and neon are isoelectronic.

Determine the electron configuration of the following ions and write which noble gas they are isoelectronic with.

1.) Lithium ion2.) Magnesium ion3.) Calcium ion

Determine the electron configuration of the following ions and write which noble gas they are isoelectronic with.

1.) Lithium ion (2 electrons): 1s2

isoelectronic with helium2.) Magnesium ion (10 electrons): 1s22s22p6

isoelectronic with neon3.) Calcium ion (18 electrons): 1s22s22p63s23p6

isoelectronic with argon

Transfer of electrons Metal + Nonmetal Ions come together due to electrostatic

attraction (opposites attract)

Determine if the following compounds are ionic:

NaCl : metal and nonmetal = ionic CO2 : metal and nonmetal = not ionic


1.) CO2.) MgCl23.) CaBr2

4.) H2O5.) LiF


1.) CO = nonmetal + nonmetal = not ionic2.) MgCl2 = metal + nonmetal = ionic3.) CaBr2 = metal + nonmetal = ionic4.) H2O = metal + metal = not ionic5.) LiF = metal + nonmental = ionic

http://www.visionlearning.com/library/module_viewer.php?mid=55

Na (1 valence e-) + Cl ( 7 valence e-) Na+ ion (8 valence e-) + Cl- ion (8 valence e-):

The result is a positively charged sodium ion (left) and a negatively chorline atom (right). Both have full outer shells!

Soidum (on the left) loses its one valence electron to chlorine (on the right)

Ionic compounds organize in characteristic crystal lattice of alternating positive and negative ions.

Unit Cell: The smallest portion of a crystal lattice that shows the three-dimensional pattern of the entire lattice.

Image from: http://www.docbrown.info/page04/4_72bond2.htm

When ionic bonds are formed, the energy that is released is called the lattice energy.

Alternatively, you can think of it as the amount of energy required to break the ionic bonds of a compound.

Sodium chloride (NaCl) dissolves in water: low lattice energy

Magnesium oxide (MgO) does not dissolve in water: high lattice energy

Solid at room temperature High boiling/melting points Dissolve in water Conduct electricity Hard (the crystal is able to resist a large

force applied to it) Brittle (applied force results in fracture, not

dents)

1.) Identify the state of matter-should be a solid at room temperature

2.) Tap it-will not break (hard) OR-will fracture if it breaks (brittle)

3.) Heat it-will only melt at high temperatures

4.) Shock it-will conduct electricity

5.) Dissolve it in water-will dissolve in water

You tap the crystal and they shatter but still retain their sharp edges.

You heat the substance and after 2-3 minutes of heating it does not melt.

It dissolves in water and conducts electricity.


Yes You heat the substance and after 2-3

minutes of heating it does not melt.




minutes of heating it does not melt.Yes




minutes of heating it does not melt.Yes


Yes

Binary Ionic Compounds

Metal + Nonmetal

Cation = positive charge

Anion = negative charge

1. Write the symbol of the cation.

2. Write the charge of the cation.

3. Write the symbol of the anion.

4. Write the charge of the anion.

5. Criss-cross the charges and write as subscripts without the signs.

6. Rewrite the formula.

7. Reduce the subscripts.

8. Check your answer (the compound should be neutral).

1. Sodium oxide

2. Aluminum sulfide

3. Barium chloride

4. Magnesium oxide

1. Sodium oxide = Na2O

2. Aluminum sulfide = Al2S3

3. Barium chloride = BaCl2

4. Magnesium oxide = MgO

The metal will have its charge listed behind its name as a roman numeral in parentheses.

Example:Iron(III) bromide = FeBr3

Exceptions: Groups 1&2, Ag, and Zn don’t have Roman numerals because they have only one charge!

Copper(II) chloride

Tin(IV) iodide

Chromium(III) oxide

Copper(II) chloride = CuCl2

Tin(IV) iodide = SnI4

Chromium(III) oxide = Cr2O3

Polyatomic Ionic Compounds

An ion made up of one atom.

A charged group of 2 or more covalently bonded atoms.

When writing the polyatomic ion, put parentheses around the formula.

When criss-crossing the charges, drop the subscript behind the parentheses.

NEVER change any subscripts inside the parenthesis.

1. Sodium Phosphate2. Calcium Nitrate3. Magnesium Hydroxide4. Potassium Sulfate5. Calcium Acetate6. Chromium (III) Nitrite7. Magnesium Hydrogen Carbonate

1. Sodium Phosphate: Na3PO4

2. Calcium Nitrate: Ca(NO3)2

3. Magnesium Hydroxide: Mg(OH) 2

4. Potassium Sulfate: K2SO4

5. Calcium Acetate: Ca(C2H3O2) 2

6. Chromium (III) Nitrite: Cr(NO2) 3

7. Magnesium Hydrogen Carbonate: Mg(HCO3)2

Binary Ionic Compounds

1. Write the name of the cation.

2. Write the name of the anion, change the ending to –ide.

Examples: RbCl = rubidium chloride K2S = potassium sulfide

1. CaBr2

2. MgS

3. NaBr

4. AlP

1. CaBr2 = calcium bromide

2. MgS = magnesium sulfide

3. NaBr = sodium bromide

4. AlP = aluminum phosphide

1. Write the name of the cation.

2. Write the charge of the cation using a roman numeral inside of parentheses.

3. Write the anion, change the ending to –ide.

Metals in Groups 1 and 2, Zinc and Silver are the only metals that will not follow the stock system because they only ever have one charge.

1. CuCl2 = copper(II) chloride

2. FeCl2

3. CuBr

4. Cu2O

1. CuCl2 = copper(II) chloride

2. FeCl2 = iron(II) chloride

3. CuBr = copper(I) bromide

4. Cu2O = copper(I) oxide

Polyatomic Ionic Compounds

1. Name the cation.

2. Name the anion.

3. If the anion is monatomic, change the ending to –ide.

4. Note: Only one polyatomic ion is a cation.

1. Ca3(PO4) 2

2. NaOH3. Ba(C2H3O2)2

4. MgSO4

5. (NH4)2S

1. Ca3(PO4) 2 : Calcium Phosphate2. NaOH : Sodium Hydroxide3. Ba(C2H3O2)2 : Barium Acetate4. MgSO4 : Magnesium Sulfate5. (NH4)2S : Ammonium Sulfide

chapter 5: ions and ionic compounds

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