1. Unit 4: Formulas and Equations (If we ever get Review Books it will be Chapter 2)

2. Lesson 1: What Formulas Can Tell Us AIM: How can we distinguish between qualitative and quantitative information?  What do these words look/sound like? Quantitative Qualitative

3. Chemical Symbols : Each element has a unique one-, two-, or three-letter symbol The first letter is always capitalized (Periodic Table and Table S) A subscript is a small number sometimes written after a chemical symbol. It tells how many of each atom are present. Almost all symbols are written without a subscript and are monatomic (only 1 atom) Mn, S, Co, Na, V Page 1

4. Symbols with Subscripts Diatomic Molecules : elements that exist in nature as two identical atoms covalently bonded together Br 2, I 2, N 2, Cl 2, H 2, O 2, F 2 Page 1

5. Parentheses with Subscripts If a subscript is written after symbols in parentheses, there are that many of everything in the parentheses How many of each type of atom? Ca(OH) 2 Zn(NO 3 ) 2 Ca = O = Zn = N = H = O = Page 1

6. Coefficients Coefficient: number written in front of a formula, applies to the entire formula multiply coefficient and subscript to find number of each type of element 2 NH 4 : N = H = 3 C 2 H 6 : C = H = Page 1 6 KOH4 O 2

7. Chemical Formulas : compounds are composed of elements chemically combined in fixed ratios Formulas use chemical symbols and numbers to show both qualitative and quantitative information about a substance Qualitative : information cannot be counted or measured (a QUALITY) Tell what elements are in the compound Quantitative : information that can be counted or measured (a QUANTITY) Tells number of atoms of each element in the compound (subscript and coefficient can give us this info) Page 1 2 CH 4 NaCl C 6 H 12 O 6

8. Homework Finish both sides of worksheet Look through notes and study vocabulary from today chemical symbols subscripts coefficients monatomic and diatomic molecules qualitative and quantitative information

9. Do Now, on top of Page 2 Take out your Reference Tables and homework Determine the qualitative and quantitative information in the following examples: CaCO 3 Zn 3 (PO 4 ) 2 Qualitative: Qualitative: Quantitative: Quantitative:

10. Lesson 2: Types of Formulas all can be reduced to

11. AIM: What are the different types of formulas? Molecular formula : shows the actual ratio of atoms covalently bonded substances form molecules C 6 H 12 O 6 H 2 O 2 Empirical : simplest ratio CH 2 O HO C 2 H 8 NH 4 Page 2 divide by 6divide by 2

12. Sometimes a molecular formula is a multiple (larger version) of the simplified empirical formula molecular C 6 H 12 O 6 is 6 times bigger than empirical CH 2 O Sometimes a molecular formula is also an empirical formula Water, H 2 O : can’t be simplified further Ionic formulas are always empirical formulas Empirical formulas show “related” or similar molecules with the same ratio of atoms  write this part in Page 2

13. Is it a molecular or empirical formula? If molecular, rewrite it as an empirical.

14. Hydrates : compounds that contain definite amounts of built-in water molecules Ex: BaCl 2  2 H 2 O Barium chloride traps 2 water molecules Hydrates