Formula writing. IONS Cation ion – usually metals positive ion (+) loses electrons Anion ion –...
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Transcript of Formula writing. IONS Cation ion – usually metals positive ion (+) loses electrons Anion ion –...
Formula writing
IONS
Cation ion – usually metalspositive ion (+)loses electrons
Anion ion – usually nonmetalsnegative ion (-)gainies electrons
Ionic Compounds- transfer of electron(s)
Ionic compound must be neutral (total + = total -)1. Write symbol of each ion2. See if the charges balance outIf yes, write formulaIf no, then criss-cross number (ONLY) of charges (lowest whole
number ratio)Sodium chloride calcium chloride
Na + Cl -
Same (1+ = 1-)
NaCl
Ca 2+ Cl 1-
2+ = 1-
CaCl2
We do not show 1’s in formulas
More examples
Sodium oxide calcium nitrate
Aluminum sulfate iron (III) chloride
Na 1+ O 2-
Na2O
Ca 2+ NO3 1-
Ca(NO3)2
You need the () since your ion contains more than one element and you need 2 or more of them to balance the formula
Al 3+ SO4 2-
Al2(SO4)3
Fe 3+ Cl 1-
FeCl3
Transition metals will usually have roman numerals. They tell you the CHARGE of the cation
Nomenclature of ionics(naming)
1) Id the cation.2) Ask if it is a transition metal, Sn, or Pb?
-If no then just name each ion.-If yes, then name each ion leaving a space after the cation for roman numerals.
CaCl2 FeCl2
Calcium chloride Iron ( ) chloride
See next slide on how to determine the roman numeral
How to figure out the charge of the cation?
Remember the total number of positives must equal the number of negatives. We know the charge of the anion, so do the math.
FeCl2
Cl 1-
Cl 1-Fe
So what charge must the Fe have to cancel out the 2-’s?2+
Therefore it is iron (II) chloride. The roman numeral tells us the charge on the iron.
Let’s try some more.
Co(NO3)3 Ni2(SO4)3
What is the charge for each anion?
How many anions are present?
Total number of negatives
What charge must the cation have to cancel the negatives out?
Charge of cation
Name of each ionic compound
1- 2-
3 3
(1-)(3) =3- (2-)(3)=6-
3+ = 3- 6+ = 6-
3+ (6+)/2= 3+
Cobalt(III) nitrateNickel(III) sulfate
Molecular compounds
Contains all nonmetals and use prefixesMono- 1 (used sparingly with oxygen)Di – 2 tri -3 tetra – 4 penta- 5Hexa – 6 hepta – 7 octa – 8 nona – 9Deca- 10Nitrogen trichloride diphosphorus tetraoxide
NCl3P2O4
Acids – Contain H’s listed first
Remember the followingFocus on anion and then add appropriate number of H’sBinary acid (HX) only 2 elementsHydro- -ic acid
Tertiary acid (3 elements)Hypo- -ite hypo- -ous acid -ite -ous acid -ate -ic acidPer- -ate per- -ic acid
Remember you ate it and it tasted icky
Naming and formula writing for acids
H2SO4 H2CO2 HF
Nitric acid sulfurous acid hydrochloric acid
H 1+ NO3 1-
HNO3
H 1+ SO3 2-
H2SO3
H 1+ Cl 1-
HCl
Sulfate so the –ate becomes -ic
Sulfuric acid
Carbonite so the –ite becomes -ous
Carbonous acid
Binary so hydro- -ic acid
Hydrofluoric acid
nitrate
sulfite