Chapter 9. Chemical Names and Formulas. Objectives for 9.1 (pgs 253-258). By the end of this section you WILL be able to… ID charges of monatomic ions by using PT Name ions Define polyatomic ion and write names and formulas of most common ones
Chemical Names and Formulas
-Ions formed from a single atom
-Charge determined by number of valence electrons
-Form when elements LOSE electrons
-Usually what type of elements?
-The name of the element followed by the word ion.
Na+ is sodium ion, Mg2+ is Magnesium Ion
-Form when elements GAIN electrons
-Usually form from what type of elements?
-Named for the element but have the suffix –ide
Cl- is chloride N3- is nitride
iron (II) and iron (III) – preferred over Classical naming system
-These anions contain different numbers of oxygen atoms
hydrogen ___ ate (or ite)
HSO3 -2 is called hydrogen sulfite
HSO4-2 is called________________
ClO- is called hypochlorite
SO2-2 would be called_________________
The prefix per- indicates that there is one MORE oxygen than the oxyanion with the –ate ending.
ClO4- is called perchlorate
PO53- is called _______________
End of section 9.1 What are your questions?
9.2 Naming and Writing Formulas
-Compounds composed of two different types of elements
For example: Iron (III) Chloride = FeCl3
Steps to writing balanced Formulas
Na+Cl- or Ca2+Cl-
Na+ Cl- or Ca2+ Cl-
The cross-over method also works for polyatomic ions. However, you must place parentheses around the entire ion to signify more than one.
Lead (II) Sulfate
Iron (II) acetate
Tin (IV) chromate
a. Calcium hydroxide
b. Iron (II) sulfate
“If I set for myself a task, be it so trifling, I shall see it through. How else shall I have confidence in myself to do important things?”
-a substance that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water
-The general form is HnX
- The name is dependent upon the name of the anion
(E.g. HCl = hydro-chlor-ic acid)
(E.g. H2SO3 = sulfur-ous acid)
Rule 3 - if the anion starts with “hypo” and ends with “-ite”, the acid name starts with “hypo” and ends with “-ous” (E.g. HClO = hypo-chlor-ous acid)
Use the same steps we did when writing formulas only backwards
You should know your polyatomic Ions by now (they’re not going away)
-Name bases as you would any other ionic compound
Examples: H2O and H2O2 CO and CO2 N2O and N2O4