1. The Structure of Matter How atoms form compounds
Chapter 4
The Structure of Matter
How atoms form compounds

2. Compounds Formed when two or more elements combine
Must make a chemical change
New properties
Atoms from the different elements form bonds
Chemical Bond- the attractive force that holds different atoms or ions together

3. Compounds Every compound has a specific ratio of atoms
Written as a chemical formula
H2O, C12H22O12, NaCl
The ratio is the same every time, every where
Different ratio means a different compound

4. Chemical Structure Shows how the atoms are arranged in the compound
How the atoms or ions are connected
In order to specify where we need
Bond length- distance between the nuclei
Bond angle- Angle between atoms (requires two bonds)

5. Models
Ball and stick- Ball represents atoms, stick represents bonds
Easy to see bond angles
Structural formulas- drawn with connections between atoms shown. H C O H O

6. Models
Space-filling – Shows that atoms the right size and in the right place.

7. C4H9O2N

8. 2 Types of structures Networks
A large number of atoms, all bonded together
Atoms bonded
Or ions opposite charges

9. Network Solids Many atoms all bonded together Quartz is SiO2
Major component of rocks.
Each Silicon bonded to 4 oxygen atoms
Angle is 109.5º
Gives it a strong rigid structure
Makes rocks hard.
Gives them a high melting and boiling point

10. Network Solids Ions bond together Opposite charges attract
All the positives get surrounded by negatives
Get a repeating pattern
Rigid
Brittle
High mp and bp

11. Molecules Specific atoms joined together Weaker attractions than ions.
Low melting and boiling points
Things we know as gases and liquids
Stronger attraction- higher melting and boiling temperatures

12. Bonding When the valence electrons interact
Atoms react to achieve full outermost energy levels
Two ways to do this
Share electrons
Transfer electrons

13. Keeping Track of Electrons
Atoms in the same column
Have the same outer electron configuration.
Have the same valence electrons.
Group 1 has 1 valence electrons
Group 2 has 2 valence electrons
Group 13 has 3 valence electrons
Group 14 has 4 valence electrons
etc

14. Helium only has 2 valence electrons1 2 8 3 4 5 6 7

15. X Electron Dot diagrams A way of keeping track of valence electrons.
How to write them
Write the symbol.
Put one dot for each valence electron
Don’t pair up until they have to X

16. The Electron Dot diagram for Nitrogen
Nitrogen has 5 valence electrons.
First we write the symbol. N
Then add 1 electron at a time to each side.
Until they are forced to pair up.

17. Write the electron dot diagram forNa Mg C O F Ne He

18. Electron Configurations for Cations
Metals lose electrons to fill their outer levels
They make positive ions.

19. Electron Dots For Cations
Metals will have few valence electrons Ca

20. Electron Dots For Cations
Metals will have few valence electrons
These will come off Ca

21. Electron Dots For Cations
Metals will have few valence electrons
These will come off
Forming positive ions
Ca+2

22. Electron Configurations for Anions
Nonmetals gain electrons to fill their outer levels
They make negative ions.

23. Electron Dots For Anions
Nonmetals will have many valence .electrons.
They will gain electrons to fill outer shell. P
P-3

24. Ar Stable Arrangements All atoms react to fill their outer levels
Noble gases have full outer energy levels.
8 valence electrons .
Also called the octet rule. Ar

25. Ionic Bonding
Anions and cations are held together by opposite charges.
The bond is formed through the transfer of electrons.
Electrons are transferred to fill their outer levels

26. Ionic Bonding Na Cl

27. Ionic Bonding
Na+
Cl-

28. Ionic Bonding
All the electrons must be accounted for! Ca P

29. Ionic Bonding Ca P

30. Ionic Bonding
Ca+2 P

31. Ionic Bonding
Ca+2 P Ca

32. Ionic Bonding
Ca+2
P-3 Ca

33. Ionic Bonding
Ca+2
P-3 Ca P

34. Ionic Bonding
Ca+2
P-3
Ca+2 P

35. Ionic Bonding Ca
Ca+2
P-3
Ca+2 P

36. Ionic Bonding Ca
Ca+2
P-3
Ca+2 P

37. Ionic Bonding
Ca+2
Ca+2
P-3
Ca+2
P-3

38. Ionic Bonding
Ca3P2
Formula Unit

39. Properties of Ionic Compounds
Crystalline structure.
A regular repeating arrangement of ions in the solid.
Ions are strongly bonded.
Structure is rigid.
High melting points- because of strong forces between ions.

40. Crystalline structure

41. Do they Conduct? Conducting electricity is allowing charges to move.
In a solid, the ions are locked in place.
Ionic solids are insulators.
When melted, the ions can move around.
Melted ionic compounds conduct.
First get them to 800ºC.
Dissolved in water they conduct.

42. Metallic Bonds How atoms are held together in the solid metal
Metals hold onto there valence electrons very weakly.
Think of them as positive ions floating in a sea of electrons.

43. Sea of Electrons + Electrons are free to move through the solid.
Metals conduct electricity. +

44. Metals are Malleable Hammered into shape (bend).
Ductile - drawn into wires.

45. Malleable +

46. Malleable
Electrons allow atoms to slide by. + + + + + + + + + + + +

47. Ionic solids are brittle+ -

48. Ionic solids are brittle
Strong Repulsion breaks crystal apart. + - + - + - + -

49. Covalent bonds Nonmetals hold onto their valence electrons.
They can’t give away electrons to bond.
Still want full outer level
Get it by sharing valence electrons with each other.
By sharing both atoms get to count the electrons toward noble gas configuration.

50. Covalent bonding
Fluorine has seven valence electrons F

51. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven F F

52. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons F F

53. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons F F

54. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons F F

55. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons F F

56. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons F F

57. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons
Both end up with full energy level F F

58. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons
Both end up with full energy level F F
8 Valence electrons

59. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons
Both end up with full energy level F F
8 Valence electrons

60. Single Covalent Bond A sharing of two valence electrons.
Only nonmetals and Hydrogen.
Different from an ionic bond because they actually form molecules.
Two specific atoms are joined.
In an ionic solid you can’t tell which atom the electrons moved from or to.

61. How to show how they formed
It’s like a jigsaw puzzle.
I have to tell you what the final formula is.
You put the pieces together to end up with the right formula.
For example- show how water is formed with covalent bonds.

62. H O Water Each hydrogen has 1 valence electron
Each hydrogen wants 1 more
The oxygen has 6 valence electrons
The oxygen wants 2 more
They share to make each other happy H O

63. H O Water Put the pieces together The first hydrogen is happy
The oxygen still wants one more H O

64. H O H Water The second hydrogen attaches
Every atom has full energy levels H O H

65. Multiple Bonds
Sometimes atoms share more than one pair of valence electrons.
A double bond is when atoms share two pair (4) of electrons.
A triple bond is when atoms share three pair (6) of electrons.

66. C O Carbon dioxide CO2 - Carbon is central atom ( I have to tell you)
Carbon has 4 valence electrons
Wants 4 more
Oxygen has 6 valence electrons
Wants 2 more C O

67. Carbon dioxide
Attaching 1 oxygen leaves the oxygen 1 short and the carbon 3 short C O

68. Carbon dioxide
Attaching the second oxygen leaves both oxygen 1 short and the carbon 2 short O C O

69. Carbon dioxide
The only solution is to share more O C O

70. Carbon dioxide
The only solution is to share more O C O

71. Carbon dioxide
The only solution is to share more O C O

72. Carbon dioxide
The only solution is to share more O C O

73. Carbon dioxide
The only solution is to share more O C O

74. Carbon dioxide
The only solution is to share more O C O

75. O C O Carbon dioxide The only solution is to share more
Requires two double bonds
Each atom gets to count all the atoms in the bond O C O

76. O C O Carbon dioxide The only solution is to share more
Requires two double bonds
Each atom gets to count all the atoms in the bond
8 valence electrons O C O

77. O C O Carbon dioxide The only solution is to share more
Requires two double bonds
Each atom gets to count all the atoms in the bond
8 valence electrons O C O

78. O C O Carbon dioxide The only solution is to share more
Requires two double bonds
Each atom gets to count all the atoms in the bond
8 valence electrons O C O

79. Another way of indicating bonds
Often use a line to indicate a bond
Called a structural formula
Each line is 2 valence electrons H O H H O H =

80. H C N H C O H Structural Examples
C has 8 electrons because each line is 2 electrons
Ditto for N
Ditto for C here
Ditto for O
H C N H
C O H