criss-cross notes. criss-cross method criss-cross is a _________ to help you find chemical...
Post on 17-Jan-2016
215 Views
Preview:
TRANSCRIPT
Criss-cross notes
Criss-Cross MethodCriss-cross is a _________ to help you find chemical __________ when you _________ atoms.
shortcut
formulascombine
**Formulas contain both the ________ in a compound and the _______ of that element.elementsamount
How Many?
NaCl = 1 sodium1 chlorine
MgCl2 =
1 magnesium2 chlorines
This number is called a ________subscript
It tells you the _______ of the atom ________ in front of it!
amountdirectly
First – you need to determine the _________ number for each atom.oxidation
To get started…
You can find them in the ______- ______ corner on the Periodic Table.
upperright
OxidationOxidation numbers are the _____ that will form when atoms _________ their _________ shells.
ions
complete valence
Cl Cl-1
Oxidation number
More than one?Many atoms have more than one oxidation state!
We will use the ______ one listed!
first
(This is the one most _________ formed in nature!)
commonly
Find the correct formula for a compound!!•Use the oxidation #’s•Put the _______ one first
H+1 + O-
2 H2O
positive
What just happened?By switching the numbers, the _________ number of one atom becomes the _________ for the other!
oxidation subscript
This also makes sure that we end up with a _______ compound – all the ________ of the ions add up to ______.
neutralcharges
zero
Stuff to remember…‘Ones’ are ________. (Think Math!)
invisible
If both of your ions have the _____ oxidation number -- ______ to the ______ common number!
samereduce lowest
It will make more sense after examples…
Ca + Br CaBr2+2 -1
Mg + Cl MgCl2+2 -1
Sr + O Sr2O2+2 -2 SrO
Don’t forget the rules for naming:1. ______ always goes first!Metal
2. ________ goes second – and ends in _____!
Nonmetal“-ide”
top related