Chemical Formulas and Names for Ionic Compounds. Terminology Review: A chemical formula uses...
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Transcript of Chemical Formulas and Names for Ionic Compounds. Terminology Review: A chemical formula uses...
Terminology Review:
A chemical formula uses chemical symbols to represent a particular compound.
Compound – 2 or more different elements chemically bonded together in a fixed proportion
What are Ionic Compounds?
Ionic compounds
- when one or more electrons are transferred from one atom to another, creating a neutral compound- pure substances usually consisting of one metal (donor or giver of electrons – therefore pos. charge) and one non-metal (receiver of electrons – therefore neg. charge)
Some Properties of Ionic Compounds:
- high melting points- ability to form crystals- dissolve in water to form solutions that
conduct electricity- solid at room temperature
Crystal Lattice Solid
Conductivity Soluble in Water
How are Ionic Compounds formed?
Ionic bonds - attraction between oppositely charged ions
How do ions form?
- when one or more electrons move from a metal atom over to a non-metal atom
a) & b) Ion formed from elementsa) Write the symbol for the metal first, then the non-metal.b) Determine the ion charge each element would form.
Write the charge to the upper right of the symbol.
Elements to Combine
a) b)Ion formed
(Element symbol and charge)
MagnesiumChlorine
Mg2+ Cl-
REVIEW – What’s the Charge?
Remember:Look at the valence electrons and ask yourself “What’s
easiest?”.
Let’s review……….
Note the names of the non-metals when they turn into ions.
Predicting Ionic Charges
Group 1Group 1::Lose 1 electron to form Lose 1 electron to form 1+1+ ions ions
HH++ LiLi++ NaNa++ KK++
Predicting Ionic Charges
Group 2Group 2::Loses 2 electrons to form Loses 2 electrons to form 2+2+ ions ions
BeBe2+2+ MgMg2+2+ CaCa2+2+ SrSr2+2+ BaBa2+2+
Predicting Ionic ChargesGroup 13Group 13:: Loses 3 Loses 3 electrons to form electrons to form 3+3+ ions ions
BB3+3+ AlAl3+3+ GaGa3+3+
Predicting Ionic ChargesGroup 14Group 14:: Lose 4 Lose 4 electrons or gain electrons or gain 4 electrons?4 electrons?
Neither!Neither! Group 14 Group 14 elements rarely elements rarely form ions.form ions.
Predicting Ionic Charges
Group 15Group 15:: Gains 3 Gains 3 electrons to form electrons to form 3-3- ions ions
NN3-3-
PP3-3-
AsAs3-3-
Nitride
Phosphide
Arsenide
Predicting Ionic Charges
Group 16Group 16:: Gains 2 Gains 2 electrons to form electrons to form 2-2- ions ions
OO2-2-
SS2-2-
SeSe2-2-
Oxide
Sulfide
Selenide
Predicting Ionic Charges
Group 17Group 17:: Gains 1 Gains 1 electron to form electron to form 1-1- ions ions
FF1-1-
ClCl1-1-
BrBr1-1-Fluoride
Chloride
Bromide
II1-1- Iodide
Predicting Ionic Charges
Group 18Group 18:: Stable Stable Noble gases Noble gases do do notnot form ions! form ions!
Predicting Ionic ChargesGroups 3 - Groups 3 - 1212::
Many Many transitiontransition elements elements have more than one possible oxidation have more than one possible oxidation state.state.Iron(II) = Fe2+ Iron(III) = Fe3+
Predicting Ionic ChargesGroups 3 - Groups 3 - 1212::
Some Some transitiontransition elements elements have only one possible oxidation state.have only one possible oxidation state.
Zinc = Zn2+ Silver = Ag+
c) Determine the number of each ion needed to balance the charge.
Elements to Combine
a) b)Ion formed
(Element symbol and charge)
c) Balance the
charges
MagnesiumChlorine
Mg2+ Cl- Mg2+ Cl-
Cl-
Total: 2 + and 2 –
Overall charge = 0
Criss-Cross Rule: Place the charge of one ion as the subscript of the other ion.
d) Write the chemical formulaRewrite the symbols together (no spaces) with the number of each needed as subscripts, reduce if possible
Elements to Combine
a) b)Ion formed
(Element symbol and charge)
c) Balance the
charges
d)Write the chemical formula
MagnesiumChlorine Mg2+ Mg2+ Cl-
MgCl2 Cl-
Cl-
e) Write the name of the metal first, then the nonmetal by changing
the ending to “ide”.
Elements to Combine
a) b)Ion formed
(Element symbol and charge)
c) Balance the
charges
d)Write the chemical formula
e)Name the compound
MagnesiumChlorine
Mg2+ Mg2+ Cl- Cl-
Cl- MgCl2 Magnesium Chloride
Polyatomic Ions
A polyatomic ion
• is a group of atoms.
• has an overall ionic charge.Some examples of polyatomic ions are
NH4+ ammonium OH− hydroxide
NO3−
nitrate NO2−
nitrite
CO32−carbonate PO4
3− phosphate
HCO3− hydrogen carbonate(bicarbonate)
Naming Polyatomic Ions
The names of common polyatomic anions
• end in ate.
NO3− nitrate PO4
3− phosphate
• with one oxygen less end in ite.
NO2− nitrite PO3
3− phosphite
Naming Compounds with Polyatomic Ions.
• The positive ion is named first, followed by the name of the polyatomic ion.
NaNO3 sodium nitrate
K2SO4 potassium sulfate
(NH4)3PO3 ammonium phosphite