2. COMPOUNDS AND MOLECULES 4.1 vid

3. WHAT ARE COMPOUNDS? Two or more elements chemically combined to form new substances.

4. WHAT ARE COMPOUNDS? Chemical Bonds – the attractive forces that hold different atoms or ions together Bonds distinguish compounds from mixtures.

5. CHEMICAL FORMULA C 12 H 22 O 11 can only be sugar H 2 0 can only be water

6. PARTS TO THE FORMULAS 2H2O2H2O Coefficient Subscript

7. PARTS TO THE FORMULAS Coefficient – gives the amount of molecules or moles Subscript – tells the number of atoms or ions

8. CHEMICAL STRUCTURE Bond length -the distance between two bonded atoms Bond angle -the angle formed between two bonded atoms

9. MODELS OF COMPOUNDS Ball and stick model -atoms are represented balls, bonds are represented by sticks. O H H Bond length Bond Angle

10. MODELS OF COMPOUNDS Structural formulas -chemical symbols represent the atoms. HH O

11. Space-filling -show the space occupied by each atom represented in the compound. Hydrogen Oxygen

12. STRUCTURE OF COMPOUNDS Network Structures = strong solids Molecules= weak solids, liquids, or gases

13. IONIC AND COVALENT BONDING 4.2 fun

14. WHY BOND? Atoms bond so they can become stable! They want to achieve a full outer energy level They want 8 electrons.

15. 1. IONIC BOND A bond formed by the attraction between oppositely charged ions. The joining of a positive metal ion and a negative nonmetal ion Na + + Cl - NaCl

18. IONIC BOND Formed by transferring electrons Now each ion will have 8 valence electrons Na + + Cl - NaCl

20. IONIC BOND PROPERTIES They form network structures high melting points Good conductors of electricity when dissolved or melted because of their ions

22. METALLIC BOND Formed by the attraction between positively charged metal ions and the electrons around them.

23. METALLIC BOND Held together by free flowing electrons Hold metallic elements together

26. COVALENT BONDS Formed when atoms share one or more valence electrons Formed between non-metals May form single, double, or triple bonds

29. COVALENT PROPERTIES They are poor conductors of electricity (no ions) Low melting points. form molecules

30. POLYATOMIC ION An ion made of two or more atoms that are covalently bonded and that act like a single ion. A molecule with a charge Examples: carbonate (CO 3 ) -2 Nitrate (NO 3 ) -1

31. Fun

32. COMPOUND NAMES AND FORMULAS 4.3

33. REMEMBER!!!!!!!! If it starts with metal it is an ionic compound If it starts with a nonmetal it is a covalent compound If the formula contains a parentheses (polyatomic ion) it contains both ionic and covalent bonds If it is just a metal it is metallic

34. WRITING IONIC FORMULAS Calcium Fluoride Step 1 - Look up both positive and negative ions Ca 2+ F -1

35. WRITING IONIC COMPOUNDS Step 2 Criss-cross numbers down, making subscripts Ca 2+ F -1 Ca 1 F 2

36. WRITING IONIC COMPOUNDS Step 3 Combine your new compound. Ca 1 + F 2  Ca 1 F 2

37. POLYATOMIC ION Al +3 (CO 3 ) -2 Al 2 (CO 3 ) 3 Aluminum Carbonate

38. NAMING IONIC COMPOUNDS Step one – Name the first ion in the formula Ex. CaCl 2 – calcium Na 2 (SO 4 ) - sodium

39. NAMING IONIC COMPOUNDS Step two – Name the second ion Ex. CaCl 2 –Calcium Chloride Na 2 (SO 4 )-sodium sulfate

40. PROBLEM Ex. Fe 2 O 3 and FeO are different compounds from different ions Fe 3+ O 2- = Fe 2 O 3 Fe 2+ O 2- = FeO

41. SOLUTION-ROMAN NUMERALS Same naming scheme Add a Roman Numeral to identify the charge of the metal ion.

42. SOLUTION-ROMAN NUMERALS Fe 2 O 3 = iron(III)Oxide FeO = iron(II)Oxide Remember!!!  R.N. is the charge, not the subscript of the metal.

43. NAMING COVALENT COMPOUNDS Mono – 1 Di - 2 Tri - 3 Tetra - 4 Penta - 5 Hexa – 6 Hepta - 7 Octa - 8 Nona - 9 Deca - 10

44. NAMING COVALENT COMPOUNDS Step 1 Identify the number of atoms in the first element Ex. H 2 Otwo H atoms

45. NAMING COVALENT COMPOUNDS Step 2 Identify the number of atoms in the 2 nd element. Ex. H 2 Oone O atom

46. NAMING COVALENT COMPOUNDS Step 3 Name the compound with the appropriate prefixes. Ex. H 2 O dihydrogen monoxygen

47. NAMING COVALENT COMPOUNDS Step 4 add an -ide ending to the second element Ex. Dihydrogen monoxide

48. EMPIRICAL FORMULA The simplest chemical formula of a compound. Different covalent compounds can have same empirical formula