Download 3. Name and write formulas for Ionic Compounds containing

Chapter Four Nomenclature…
TOPICS:
1. Name and write formulas of BINARY compounds of a metals and a
nonmetal (Ionic Compounds)
2. Name and Write Formulas for BINARY Compounds containing only nonmetals (Covalent Molecules)
3. Name and write formulas for Ionic Compounds containing polyatomic
ions
4. Name and write formulas for acids
1. Name and write formulas of BINARY compounds of a metals
and a nonmetal (Ionic Compounds)
Writing Formulas: Metal and a nonmetal
-Look up charges for each ion using periodic table and/or table of
common ions. (note Roman Numeral on + ion corresponds to + charge)
-Write each symbol with the charge as a superscript (+ ions always goes
first)
-Criss-cross charges so that they become subscripts and erase + and –
-erase 1’s …not needed
-If possible reduce to lowest whole number ratio (not often necessary)
examples:p 119 #25
Naming Compounds: metal and a non-metal
-positive ion (cation) is named first, take the name of the element, if the
cation can have more than one charge use a Roman Numeral to indicate
what charge
- negative anion (anion) is the first part of element name followed by -ide
(example: chloride, oxide, sulfide…etc)
examples:p 118 #6,#8
2. Name and Write Formulas for BINARY Compounds containing
only non-metals (Covalent Molecules)
non-metal and non-metal use prefixes
1
mono (only with
2
di
second)
4 tetra
5
penta
7 hepta
8
octa
3 tri
6
hepta
Naming Covalent Compounds:
-name the first element using the element name
-second element is modified with –ide
-use prefixes to denote number of atoms present (mono is never used with
first element
-double vowels are dropped for easier pronunciation
examples: p 104 exercise 4.4 and 4.5
Writing Formulas for Covalent Compounds:
-use prefixes to denote number of each atom and write as subscript
examples: p 119 #26
3. Name and write formulas for Ionic Compounds containing
polyatomic ions
polyatomic ions : several atoms bound together that exist as an ion. (see table p 109 and
handout)
These formulas ion cannot be altered, when you need more than one of them you must
enclose the formula in ( ) and write a subscript outside on the lower left to indicate how
many!!!!!
You do not have to memorize these, but the more you use them the more familiar you
SHOULD become!!!
Writing Formulas: Metal and polyatomic anion or two polyatomic ions
-Look up charges for each ion using periodic table and/or table of
common polyatomic ions. (note Roman Numeral on + ion corresponds to
+ charge)
-Write each symbol or ions with the charge as a superscript (+ ions
always goes first)
-Criss-cross charges so that they become subscripts and erase + and –
- Use ( ) around polyatomic ion if there is more than one
-erase 1’s …not needed
-If possible reduce to lowest whole number ratio (not often necessary)
examples: p 119 #27
Naming Compounds: Metal and polyatomic anion or two polyatomic ions
-positive ion (cation) is named first, take the name of the element, if the
cation can have more than one charge use a Roman Numeral to indicate
what charge or take name of positive polyatomic cation
- negative polyatomic anion name goes second-refer to table!!!!
examples:p 111 ex 4.7
4. Name and write formulas for acids
acid formulas begin with H
- acids are formed when molecules dissolve in water to produce H+ ions
- an acid can be viewed as one or more H+ ions attached to a negative
ion
RULES for naming acids:
-When the anion does not contain oxygen use prefix hydro- and suffix –
ic attached to root name of anion
examples:
- When the anion contains oxygen
-ate- ion becomes –ic acid
-ite ion becomes –ous acid
examples:
Writing formulas for acids:
When writing formulas acids the same rules apply only in reverse and H
always comes first with a + 1 charge
examples: p 119 # 24,28
In review, writing formulas and naming compounds is easy enough when
working with one type….however in the “real world” you have to be able to
distinguish what rules apply….so I will ask you Repeatedly
1) is it a metal and a nonmetal (ionic)
2) is it 2 non-metals (molecule-covalently bonded)
3) is it metal and poly anions or 2 polyatomic ions (ionic)
4) does it begin with H….is it an acid