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Blackstone-Millville Regional School District

175 Lincoln Street, Blackstone MA 01504     508-883-4400  Fax# 508-883-9892

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Periodic Table of the Elements

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Significant Figures:

RULE #1 - All digits 1 through 9 are significant

If the mass of an object is measured as 12.3 g, this means that the mass is known to lie between 12.2 and 12.4 g. There are 3 significant figures in 12.3.If the mass of an object is measured as 12.3456 g, this means that the mass is known to lie between 12.3455 and 12.3457 g. There are 6 significant figures in 12.3456.

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RULE #2 - Zero is significant when it is between two non-zero digits.

The quantities 306, 30.6, 3.06 and .306 all contain 3 significant figures since the 0 between the 3 and 6 is significant.

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RULE #3 - A terminal zero to the right of a decimal point in a number greater than one is significant.

The quantities 279.0, 27.90 and 2.790 all contain 4 significant figures.

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RULE #4 - A terminal zero to the right of a decimal point in a number less than one is significant.

The quantities .2790 and .27900 have 4 and 5 significant figures respectively.

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RULE #5 - A zero used to fix a decimal point in a number less than one is not significant.

The quantities 0.456, 0.0456 and 0.00456 all contain 3 significant figures.

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 Symbols and Charges for Monoatomic Ions
 
Fixed Charge
 
Symbol Name Symbol Name
H+ hydrogen ion H- hydride
Li+ lithium ion F-  fluoride
Na+ sodium ion Cl- chloride
K+ potassium ion Br- bromide
Rb+ rubidium ion I- iodide
Cs+ cesium ion O2- oxide
Be2+ beryllium ion S2- sulfide
Mg2+ magnesium ion Se2- selenide
Ca2+ calcium ion Te2- telluride
Sr2+ strontium ion N3- nitride
Ba2+ barium ion P3- phosphide
Ra2+ radium ion As3- arsenide
Ag+ silver ion Ni2+ nickel ion
Zn2+ zinc ion Al3+ aluminum ion
 
Note that the letters in an ion's name before the -ide ending is the stem.
For example, the stem for bromide is brom-. The P for phosphide is a capital P.
Some sources will have nickel as a variable charge monoatomic ion, the charges
being +2 and +4.
 
Symbols and Charges for Monoatomic Ions
 
Variable Charge
 
 Systematic name Common Systematic name Common
Symbol (Stock system) name Symbol (Stock system) name
Cu+ copper(I) cuprous Hg22+ mercury(I) mercurous
Cu2+ copper(II) cupric Hg2+ mercury(II) mercuric
Fe2+ iron(II) ferrous Pb2+ lead(II) plumbous
Fe3+ iron(III) ferric Pb4+ lead(IV) plumbic
Sn2+ tin(II) stannous Co2+ cobalt(II) cobaltous
Sn4+ tin(IV) stannic Co3+ cobalt(III) cobaltic
Cr2+ chromium(II) chromous Au+ gold(I) aurous
Cr3+ chromium(III) chromic Au3+ gold(III) auric
Mn2+ manganese(II) manganous
Mn3+ manganese(III) manganic
 
 
Symbols and Charges for Polyatomic Ions
 
Formula Name Formula Name
NO3- nitrate ClO4- perchlorate
NO2- nitrite ClO3- chlorate
CrO42- chromate ClO2- chlorite
Cr2O72- dichromate ClO- hypochlorite
CN- cyanide IO4- periodate
MnO4- permanganate IO3- iodate
OH- hydroxide IO-  hypoiodite
O22- peroxide BrO3- bromate
NH2- amide BrO- hypobromite
CO32- carbonate HCO3- hydrogen carbonate (bicarbonate)
SO42- sulfate HSO4- hydrogen sulfate (bisulfate)
SO32- sulfite HSO3- hydrogen sulfite (bisulfite)
C2O42- oxalate HC2O4- hydrogen oxalate (binoxalate)
PO43- phosphate HPO42- hydrogen phosphate
PO33- phosphite H2PO4- dihydrogen phosphate
S2O32- thiosulfate HS- hydrogen sulfide
AsO43- arsenate BO33- borate
SeO42- selenate B4O72- tetraborate
SiO32- silicate SiF62-  hexafluorosilicate
C4H4O62- tartrate NH4+ ammonium

C₂H₃O₂^- acetate (CH₃COO^-)

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© Matt Kankash, 2003