1. Agenda
Targets
Element Review
Elements Quiz
Modeling Matter
Writing Chemical Formulas
Study Guide Going Home!
Distinguish among a chemical symbol, formula, and a chemical equation.
Determine the formula and name of a simple ionic compound, when provided with the anion’s and cation’s names and charges.

2. How does the water dissolve the ionic compounds?

3. Agenda
Targets
Element review (Quiz Friday)
Distinguish among a chemical symbol, formula, and a chemical equation.
Determine the formula and name of a simple ionic compound, when provided with the anion’s and cation’s names and charges.

4. What makes up the elements?
Protons Positive Charge
Neutrons Neutral Charge
Electrons Negative Charge

5. Elements & Ions Chlorine atom 17 protons 17 electrons
Chloride ion (-1) 17 protons 18 electrons
Oxygen atom 8 protons 8 electrons
Oxide ion (-2) 8 protons 10 electrons
Potassium atom 19 protons electrons
Potassium ion (+1) 19 protons 18 electrons

6. What changed when making an ion?
The number of electrons changed, giving it a charge
What happened to the charge when it gained electrons?
negative charge (ANION)
What happened to the charge when it lost electrons?
positive charge (CATION)

7. Oxidation Numbers are used to determine the ratio in which elements combine to form compounds.

8. Understanding Chemical
Formulas
Chemical formulas are composed of a positive half and a negative half.
Ex. - Water is a compound you know to have a formula of H2O.

9. For your graphic organizer
Write above
Cation (On Left) Anion (On Right)

10. The element with the positive oxidation number is always written first.
The element with the negative oxidation number is always written second.

11. H O The total of the oxidation numbers in a compound must equal zero.+1 -2 H O
Hydrogen’s oxidation number is +1 and oxygen’s is -2. With one H and one O, the total is not 0, it is -1!!!

12. Subscripts, small numbers to the lower right of the chemical symbol, represent the number of that element present in the compound.
The subscript of 1 is never written in a chemical formula. It is understood since the chemical symbol is there.
Add subscripts after a chemical symbol, when needed, to make the oxidation numbers total zero.
H2O

13. How to check if the formula is correct:
Multiply subscript by oxidation number for the total oxidation number of each element in a formula.
For Hydrogen:
(oxidation number +1)(subscript 2) = +2 total
For Oxygen:
(oxidation number -2)(subscript 1) = -2 total
The formula H2O is the correct formula!!!

14. There MUST be an easier way....and there is!! Ca Cl
The easiest way to think of writing chemical formulas is to use the oxidation number (without the + or -) of one element as the subscript of the other element. +2 -1
Ca Cl

15. Cross over the oxidation numbers without the charges!!!+2 -1
Ca Cl

16. Ca Cl 2
REMINDER: DO NOT write a subscript of 1. Reduce the subscripts if needed.

21. Naming Ionic and Molecular Compounds
General Rules
Positive ions (Cations) always come first
Always have the name of the element
For Example
AgCl
Begins with silver

22. How many of each element are there?
HNO3
Na2C2O4
AgCl

23. What would the chemical formula be?
H+1 O-2 Fe+2 Cl-1 Ag+3 (NO3)-3

24. Negative ion (Anions) comes next
Here’s the hard part of naming
If it is an element by itself
You put –ide on the end
For example
AgCl
Chlorine turns into chloride
MgO
Oxygen turns into oxide

25. Negative ion (Anion) If it is an element with an oxygen attached
You put an –ate on the end
For example
SO4
Sulfur tetroxide turns into sulfate
NO3
Nitrogen trioxide turns into nitrate

26. If the positive ion has more than one charge associated with it…
You need to put the charge you have in parentheses in roman numerals
For example
Iron
Has 2 charges, either +2 or +3
If we have iron +3
Iron (III)
If we have iron +2
Iron (II)

27. Subtracting an oxygen gives you’re a new name
Sulfate  sulfite (SO4  SO3) Nitrate  nitrite (NO3  NO2) Phosphate  phosphite (PO4  PO3) Carbonate  carbonite (CO3  CO2)

28. Other considerations…
NH4  Ammonium
HCO3  bicarbonate
OH  hydroxide

29. 9/10 Agenda Targets Practice before the races.
Compound Naming and formula race.
Trashball
Review Fishkill articles and identify FACTS not opinions from incident.
Determine the formula and name of a simple ionic compound, when provided with the anion’s and cation’s names and charges.