This document provides information about writing chemical formulas from names and names from formulas. It discusses ionic and molecular compounds and defines positive and negative ions. Common cations and anions are listed along with their charges. Rules are provided for determining charges of ions based on their location on the periodic table. Transition metals can have variable charges. Guidelines are given for naming monatomic anions and determining whether they end in "ide".

1. Copyright Sautter 2015

2. CHEMICAL FORMULAE*
HOW TO WRITE FORMULAS
FROM NAMES AND NAMES
FROM FORMULAS*
* SOME BOOKS USE FORMULAE ENDING IN AE WHICH IS THE LATIN
PLURAL INSTEAD OF FORMULAS
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3. TYPE OF COMPOUNDS
• (1) IONIC COMPOUNDS – THOSE CONSISTING PRIMARILY OF
METALS COMBINED WITH NONMETALS
• (A METAL COMBINED WITH A NONMETAL IS CALLED A
SALT. SODIUM CHLORIDE OR “TABLE SALT” IS NOT THE
ONLY SALT, THERE ARE MANY DIFFERENT KINDS OF
SALTS. IT HOWEVER IS ONE OF THE MOST COMMON
SALTS.)
• (2) MOLECULAR COMPOUNDS – THOSE CONSISTING OF
NONMETALS
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4. WHAT ARE IONS?
CHARGED ATOMS OR GROUPS OF ATOMS
THERE ARE TWO KINDS OF IONS, POSITIVE AND
NEGATIVE
• POSITIVE IONS ARE
ATOMS OR GROUPS
OF ATOMS WITH
MISSING ELECTRONS
• THESE IONS USUALLY
CONSIST OF METALS
• THEY ARE ALSO
CALLED CATIONS
• NEGATIVE ION ARE
ATOMS OR GROUPS OF
ATOMS WITH EXTRA
ELECTRONS
• THESE IONS USUALLY
CONSIST OF NONMETALS
• THEY ARE ALSO CALLED
ANIONS (NOT DOG IONS
AS YOU MIGHT EXPECT !!)
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5. SOME COMMON CATIONS (POSITIVE IONS)
• NAME
• SODIUM
• ZINC
• POTASSIUM
• CALCIUM
• MAGNESIUM
• COPPER II (CUPRIC)
• IRON II (FERROUS)
• IRON III (FERRIC)
• AMMONIUM*
*ONE OF THE FEW POLYATOMIC
CATIONS
• FORMULAS
• Na+1
• Zn+2
• K+1
• Ca+2
• Mg+2
• Cu+2
• Fe+2
• Fe+3
• NH4
+1
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6. SOME COMMON ANIONS (NEGATIVE IONS)
• NAMES
• CHLORIDE
• SULFIDE
• BROMIDE
• SULFATE
• SULFITE
• NITRATE
• NITRITE
• CARBONATE
• CHROMATE
• FORMULAS
• Cl-1
• S-2
• Br-1
• SO4
-2
• SO3
-2
• NO3
-1
• NO2
-1
• CO3
-2
• CrO4
-2
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7. SOME RULES REGARDING CATIONS
(POSITIVE IONS)
• IONS FROM COLUMN I
(ALKALI METALS) ON THE
PERIODIC TABLE ARE
ALWAYS +1
• IONS FROM COLUMN II
(ALKALINE EARTH METALS)
ON THE PERIODIC TABLE ARE
ALWAYS +2
• IONS FROM COLUMN II (THE
ALUMINIUM GROUP) ON THE
PERIODIC TABLE ARE +3
• THE TRANSITIONAL METALS
HAVE VARIABLE CHARGES
RANGING FROM +1 TO +5
• EXAMPLES:
• COLUMN I COLUMN II
• Na+1 Ca+2
• K+1 Mg+2
• etc. etc.
• COLUMN III
• Al+3
• Ga+3
• TRANSITIONAL METALS
• Cu+2
• Fe+2
• Cr+3
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8. TRANSITIONAL METALS WITH VARIABLE CHARGE
STATES
• SOME TRANSITIONAL
METALS CAN EXSIST AS
IONS IN TWO DIFFERENT
CHARGE STATES. SOME OF
THESE ELEMENTS ARE
COPPER, TIN, IRON,
COBALT, LEAD, MERCURY,
CHROMIUM AND
MANGANESE.
• * THESE VARIABLE CHARGES
HAVE NO PATTERN AND
MUST BE MEMORIZED
• EXAMPLES:
• COPPER +1 OR +2
• TIN +2 OR +4
• IRON +2 OR +3
• COBALT +2 OR +3
• LEAD +2 OR +4
• MERCURY +1 OR +2
• CHROMIUM +2 OR +3
• MANGANESE +2 OR +3
• * THE SAME ATOM WITH
DIFFERENT CHARGE STATES
ARE DESIGNATED USING
ROMAN NUMERIALS SUCH AS
COPPER I FOR Cu+1 OR LEAD II
FOR Pb+2
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9. RULES REGARDING FORMULAS AND NAMES FOR
ANIONS (NEGATIVE IONS)
• ANIONS FROM COLUMN VII
(HALOGENS) ARE CHARGED –1
• ANIONS FROM COLUMN VI
(OXYGEN GROUP) ARE
CHARGED –2
• ANIONS FROM COLUMN V
(NITROGEN GROUP) ARE
CHARGED –3 WHEN THE IONS
ARE SINGLE ATOMS
(MONATOMIC)
• EXAMPLES:
• COLUMN VII
• Cl-1
• Br-1
• COLUMN VI
• S-2
• O-2
• COLUMN V
• N-3
P-3
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10. NAMING MONATOMIC (SINGLE ATOM) ANIONS
• ANIONS THAT CONSIST OF
ONLY ONE ATOM END IN
ALWAYS “IDE”.
• ANIONS THAT CONSIST OF
MORE THAN ONE ATOM
BUT CONTAIN NO
OXYGEN ALSO END IN
“IDE”
• THE HYROXIDE ION IS AN
EXCEPTION IN THAT IT
CONTAINS OXYGEN AND
POLYATOMIC BUT ENDS
IN “IDE”
• CHLORIDE Cl-1
• SULFIDE S-2
• NITRIDE N-3
• CYANIDE CN-1
• THIOCYANIDE SCN-1
• HYDROXIDE OH-1
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