1. Chemical Formulas and chemical compounds Chapter 7.1

2. Objectives: Explain the significance of a chemical formula. Determine the formula of an ionic compound formed between two given ions. Name an ionic compound given its formula. Using prefixes, name a binary molecular compound from its formula. Write the formula of a binary molecular compound given its name.

3. Chemical names and Formulas There are millions of natural and synthetic chemical compounds Calcium carbonate – limestone Sodium chloride – table salt Dihydrogen monoxide – water These are their chemical and common names Chemical names help to describe the atomic makeup of the compounds

5. Indicates the relative number of atoms of each kind in a molecule. (Covalently bonded)C8H18 Subscript indicates there are 8 atoms of carbon in a molecule of octane Subscript indicates there are 18 atoms of hydrogen in a molecule of octane

6. Chemical formula for ionic compound Ionic compound consists of lattice of positive and negative ions held together by mutual attraction. Chemical formula represented by one formula unit Simplest ratio of the compounds positive and negative ions Aluminum sulfate below consists of aluminum cations and sulfate ions Al2(SO4)3 Subscript 3 refers to everything inside the parentheses giving 3 sulfate ions, with a total of 3 sulfur atoms and 12 oxygen atoms Subscript 2 refers to 2 Aluminum atoms Subscript 4 refers to 4 oxygen atoms in the sulfate ion Note: when you only have one of an atom, no subscript is used Note: parentheses are used to identify polyatomic ion as one unit

8. Examples

9. Carbon & Silicon form covalent bonds

10. d-block elements form variable charges

11. examples

12. Copper, can be Cu+1 or Cu+2

13. Iron, can be Fe+2 or Fe+3

15. Base of element + -ide ending

16. Ex: F-1 Fluoride N-3 Nitride O-2 _______ Br-1 _______

19. Name cation first : full name of cation

20. Aluminum

21. Name Anion last : base of anion + -ide

22. oxideAl2O3 aluminum oxide

26. Do not use roman numerals ( main group elements)

27. No Anions form more than one charge+2 -1 CuCl2 copper(II) chloride

30. Anion with one less oxygen has –ite ending

31. Anion with two less oxygen has hypo prefix and –ite ending

32. Anion with one extra oxygen has per prefix and –ate endingClO3-1 ClO2-1 ClO-1 ClO4-1 hypochlorite perchlorate chlorate chlorite

33. Naming Compounds with Polyatomic Ions Same as naming for ionic compounds except Name polyatomic ion as one unit Example: AgNO3 Use parentheses if more than one polyatomic ion Example Al2(SO4)3 silver nitrate Show 2 Al+3 ions and 3 SO4-2 ions aluminum sulfate

36. Old system – must know numerical prefixesmono- di- tri- tetra- penta- hexa- hepta- octa- nona- deca-

39. Write formulas for the following molecular compoundsSO3 ICl3 PBr5 sulfur trioxide carbon tetraiodide phosphorus trichloride oxygen difluoride CI4 iodine trichloride PCl3 Phosphorus pentabromide OF2