IONIC BONDING ION – any atom with more or less electrons that it is supposed to have* * Remember that the number of Electrons is supposed to be equal to the number of Protons if the atom has a neutral charge

IONIC BONDING Happens when an atom of a nonmetal takes one or more electrons from an atom of a metal so both atoms end up with eight valence electrons An electrical attraction between two oppositely charged atoms or groups of atoms.

The Octet Rule The octet rule says that atoms can become stable by having eight electrons in their outer energy level, as shown in the noble gas, Neon, (or two electrons in the case of some of the smallest atoms ).

Electron Dots For Cations  Metals will have few valence electrons  These will come off Ca

Electron Dots For Cations  Metals will have few valence electrons  These will come off  Forming positive ions Ca 2+

Electron Dots For Anions  Nonmetals will have many valence electrons.  They will gain electrons to fill outer shell. P P 3-

IONIC COMPOUNDS metal with nonmetal + ion - ion Ca+ion anion

Predicting Oxidation Number or Charge from Periodic Table

Forming Cations metals lose e - form cations oxidation #  group 1A lose 1 +1 charge1 +  group 2A lose 2 +2 charge2 +  group 3A lose 3 +3 charge3 +  group 4A lose 4 +4 charge4 +

Forming Anions Non-metals gain e - form anions oxidation #  group 7A gain 1 -1 charge 1 -  group 6A gain 2 -2 charge 2 -  group 5A gain 3 -3 charge 3 -

Oxidation Numbers

Neutral atoms come near each other. Electron(s) are transferred from the Metal atom to the Non-metal atom. They stick together because of electrostatic forces, like magnets. IONIC BONDING

Steps for writing ionic bond formulas 1. Determine the oxidation numbers for the two elements or ions. Ca = +2, Cl = -1

Steps for writing ionic bond formulas 2. Write the chemical symbols in the correct order, with the metal ion first and write the oxidation numbers as superscripts. Ca 2+ Cl -1

Ca 2+ Cl Crisscross the numbers only—not the charge signs—writing the oxidation number of one element as a subscript for the other. Don’t write number 1 either. Ca 1 Cl 2 Steps for writing ionic bond formulas Ca Cl 2

4. Determine whether the formula is in its simplest form. Reduce the subscripts to the simplest from by dividing by a common denominator. Ca +2 O -2 Ca 2 O 2 = Ca 2 O 2 CaO Steps for writing ionic bond formulas

5. Check the formula by calculating the total positive and negative charges and confirming that the total charge on the compound is zero. CaCl 2 Steps for writing ionic bond formulas Oxidation Number Subscript Calcium(+2)x(1)=+2 Chlorine(-)x(2)=-2

Practice these!  magnesium and oxygen  aluminum and bromine  sodium and sulfur  potassium and nitrogen MgO AlBr 3 Na 2 S K3NK3N

More Practice!  potassium bromide  calcium oxide  Silver fluoride KBr CaO AgF

Polyatomic ions  Groups of atoms that stick together as a unit, and have a charge PO 4 3- phosphate CO 3 2- carbonate C 2 H 3 O 4 1- acetate  Names often end in –ate or –ite

6. POLYATOMIC IONS ACT JUST LIKE ANY OTHER NEGATIVE ION WHEN BONDING Treat polyatomic ion as single unit— don’t change it in any way! Steps for writing ionic bond formulas

polyatomic ions are enclosed in parenthesis if taken more than once in the formula. A subscript outside the parenthesis multiplies everything inside. Steps for writing ionic bond formulas

 potassium hydroxide  zinc (II) carbonate  barium chlorate  aluminum phosphate Practice KOH ZnCO 3 Ba(ClO 3 ) 2 AlPO 4

 calcium acetate  sodium nitrate  aluminum hydroxide  ammonium phosphate More Practice Ca(C 2 H 3 O 2 ) 2 NaNO 3 Al(OH) 3 (NH 4 ) 3 PO 4

Naming Ionic Compounds 1. name cation - then anion 2. if anion (nonmetal) is a single element ….. then name ends in “-ide”

3. If metal have more than one possible charge (include roman numeral in parenthesis to give charge)* *All metals except: Ag +1, Zn +2, Cd +2, Al +3 Naming Ionic Compounds

 Na 2 O  Mg(OH) 2  Al(NO 3 ) 3  NH 4 Cl Practice (no transitional metals) Sodium oxide Manganese (II) oxide Aluminum nitrate Ammonium chloride

 Sn(ClO 3 ) 4  Cu 2 CO 3  Fe 2 O 3  NiSO 4 Practice with transitional metals Tin(IV) chlorate Copper (I) carbonate Iron (III) oxide Nickel (II) sulfate Hint: look at the subscript in the anion to predict the metal oxidation number.

Properties of Ionic Compounds  Crystalline structure.  A regular repeating arrangement of ions in the solid.  Ions are strongly bonded.  Structure is rigid.  High melting points- because of strong forces between ions.

Crystalline structure 3 dimension The repeating unit is called the unit cell

Crystalline structure The POSITIVE CATIONS stick to the NEGATIVE ANIONS, like a magnet.

Ionic solids are brittle

 Strong Repulsion breaks crystal apart.

Cubic

Body-Centered Cubic

Face-Centered Cubic

Do they Conduct?  Conducting electricity is allowing charges to move.  In a solid, the ions are locked in place.  Ionic solids are insulators.  When melted, the ions can move around.  Melted ionic compounds conduct.  First get them to 800ºC.  Dissolved in water they conduct.