1. CHEMICAL BONDS Chapter 19 Glencoe Physical Science

2. What atomic particle determines the chemical properties of an element?
a. protons
b. neutrons
c. electrons
d. morons

3. Which electrons determine an element’s chemical properties?
a. electrons near the nucleus of the atom
b. middle energy level(s)
c. valence electrons

4. How many valence electrons do most atoms need to become chemically stable?1 4 8 10

5. Atoms are chemically stable (or resistant to change) when their valence shells are completely filled with electrons.
For most atoms, 8 electrons are needed to be chemically stable.
Why do the Noble Gases not form compounds easily?

6. How are electrons in an atom represented?
a. Bohr Models
b. Lewis Dot Diagrams
c. both of these

7. How are valence electrons in an atom represented?
a. Bohr Models
b. Lewis Dot Diagrams
c. both of these

8. Why do chemical bonds form?

9. To become stable!!!!
(atoms will gain, lose, or share electrons in order to achieve “Noble Gas configuration.”)

10. Types of Chemical Bonds
Ionic Bonds = usually
metal + nonmetal
2. Covalent Bonds = nonmetal + nonmetal

11. Classify the following compounds as covalent or ionic:
NaCl
CO2
H2O
MgCl2
C4H10

12. Classify the following compounds as covalent or ionic:
NaCl (ionic)
CO2
H2O
MgCl2
C4H10

13. Classify the following compounds as covalent or ionic:
NaCl (ionic)
CO2 (covalent)
H2O
MgCl2
C4H10

14. Classify the following compounds as covalent or ionic:
NaCl (ionic)
CO2 (covalent)
H2O
MgCl2
C4H10

15. Classify the following compounds as covalent or ionic:
NaCl (ionic)
CO2 (covalent)
H2O (covalent)
MgCl2
C4H10

16. Classify the following compounds as covalent or ionic:
NaCl (ionic)
CO2 (covalent)
H2O (covalent)
MgCl2 (ionic)
C4H10

17. Classify the following compounds as covalent or ionic:
NaCl (ionic)
CO2 (covalent)
H2O (covalent)
MgCl2 (ionic)
C4H10 (covalent)

18. What are ions? How do ions form?

19. Ion
an atom that has gained or lost one or more electrons, therefore it has a positive or negative charge

20. Ionic Bond Usually forms between a metal and a nonmetal
Is the force of electrostatic attraction between positively and negatively charged ions

21. Ionic Charges are indicated by a Superscript
superscript -“written above”
Examples: Na+, Mg2+, Cl-, O2-

22. A transfer of electrons takes place
If an atom loses electrons it becomes ____ charged.
If an atom gains electrons, it becomes ____ charged.

23. A transfer of electrons takes place
If an atom loses electrons it becomes POSITIVELY charged.
If an atom gains electrons, it becomes NEGATIVELY charged.

24. Metals tend to lose electrons.
Nonmetals tend to gain electrons.

25. Demonstration of Ionic Bonding

26. Student Activity 1
Groups 1 and 8: Show ionic bonding between lithium and fluorine
Groups 2 and 7: Show ionic bonding between sodium and fluorine
Groups 3 and 6: Show ionic bonding between potassium and chlorine
Groups 4 and 5: Show ionic bonding between lithium and chlorine

27. Chemical Formula
Indicates the elements in a compound and the ratio of the atoms of those elements in one unit of the compound.

28. Chemical Formula Examples: NaCl; H2O The “2” in H2O is a subscript.
Subscript (“written below”)indicates the number of atoms of an element in a unit of that compound.

29. What is the ratio of sodium to chlorine in NaCl
What is the ratio of sodium to chlorine in NaCl? hydrogen to oxygen in H2O?

30. Writing Formulas for Binary Ionic Compounds
Determine the oxidation number of each ion (the number of electrons an atom gains or loses)
Oxidation numbers for the representative elements can be determined from its position on the periodic table. Oxidation Numbers for transition elements are determined from their negative ions.

33. Writing Formulas for Binary Ionic Compounds
Write the symbol of the positive ion first.
Write the symbol of the negative ion.
Add the superscripts. Is the sum zero?
If the sum does NOT equal zero, criss-cross the ionic charges.
Demonstration and Student Practice

34. Student Activity 2: Write formulas for binary ionic compounds
lithium & fluorine; magnesium & chlorine
Sodium & chlorine; calcium & bromine
potassium & bromine; strontium & chlorine
potassium & iodine; magnesium & fluorine
DO NOT ERASE the dry erase board!!!!

35. Check your work:
LiF; MgCl2
NaCl; CaBr2
KBr; SrCl2
KI; MgF2

36. Naming Binary Ionic Compounds
Write the name of the positive ion first.
Write the root of the negative ion’s name.
Change the ending to -ide.

37. Student Activity 3
Using the dry erase board, name the compounds you wrote formulas for in Activity 2

38. Check your work: 1. Lithium fluoride; magnesium chloride
2. Sodium chloride; calcium bromide
3. Potassium bromide; strontium chloride
4. Potassium iodide; magnesium fluoride

39. Roman Numerals are used with elements that have more than one common oxidation number. (This includes most of the transition elements)

40. Examples: CuBr2 is named Copper (II) bromide
PbCl2 is named Lead (II) chloride

41. EXCEPTIONS: Roman Numerals are NOT needed for silver, cadmium, and zinc:
These transition elements ALWAYS have the following oxidation numbers: Ag+ Cd2+, Zn2+

42. Examples:
AgBr is named silver bromide, and NOT silver (I) bromide, because silver always has a +1 oxidation number.
The same is true for compounds containing Cadmium or Zinc.

43. Some Special Ions: Copper (I) and (II) = Cu+ and Cu2+
Iron (II) and (III) = Fe2+ and Fe3+
Chromium (II) and (III) = Cr2+ and Cr3+
Lead (II) and (IV) = Pb2+ and Pb4+

44. Write names for:
FeS
CuCl
3. PbBr4

45. Check your work: FeS= Iron (II) sulfide CuCl= Copper (I) chloride
PbBr4 = Lead (IV) bromide

46. Write formulas from the following names:
Lead (II) bromide
Chromium (II) sulfide
copper (II) iodide

47. Check your work:
PbBr2
CrS
CuI2

48. Binary Ionic Chemical Compounds WS
Write formulas for:
Sodium bromide
Calcium chloride
Magnesium oxide
Silver chloride
Iron (III) oxide

49. Name the following compounds:
NaCl
MgCl2
Al2O3
Zn(NO2) 2
CuCl2

50. Check your work! NaBr 6. sodium chloride CaCl2 7. magnesium chloride
MgO 8. aluminum oxide
AgCl 9. zinc nitrite
Fe2O copper (II) chloride

51. CW/HW
See “Hand-outs” on class website and complete
WS1
WS2