1. Chemical Bonds

2. Atom – the smallest unit of matter “indivisible”
Helium
atom

3. electron shells Atomic number = number of Electrons
Electrons vary in the amount of energy they possess, and they occur at certain energy levels or electron shells.
Electron shells determine how an atom behaves when it encounters other atoms

4. Electrons are placed in shells according to rules:
The 1st shell can hold up to two electrons, and each shell thereafter can hold up to 8 electrons.

5. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons
C would like to
N would like to
O would like to
Gain 4 electrons
Gain 3 electrons
Gain 2 electrons

6. Why are electrons important?
Elements have different electron configurations
different electron configurations mean different levels of bonding

8. Electron Dot Structures
Symbols of atoms with dots to represent the valence-shell electrons
H He:
          
Li Be  B   C   N   O  : F  :Ne :
       
          
Na Mg  Al  Si  P S :Cl  :Ar :
       

9. Chemical bonds: an attempt to fill electron shells
Ionic bonds –
Covalent bonds –
Metallic bonds

10. Learning Check A. X would be the electron dot formula for
A. X would be the electron dot formula for
1) Na 2) K 3) Al
 
B  X  would be the electron dot formula
1) B 2) N 3) P

11. IONIC BOND bond formed between two ions by the transfer of electrons

12. Formation of Ions from Metals
Ionic compounds result when metals react with nonmetals
Metals lose electrons to match the number of valence electrons of their nearest noble gas
Positive ions form when the number of electrons are less than the number of protons
Group 1 metals  ion 1+
Group 2 metals  ion 2+
Group 13 metals  ion 3+

13. Formation of Sodium Ion
Sodium atom Sodium ion
Na  – e  Na +
( = Ne)
11 p p+
11 e e-

14. Formation of Magnesium Ion
Magnesium atom Magnesium ion 
Mg  – 2e  Mg2+
(=Ne)
12 p p+
12 e e-

15. Some Typical Ions with Positive Charges (Cations)
Group 1 Group 2 Group 13
H+ Mg2+ Al3+
Li+ Ca2+
Na+ Sr2+
K+ Ba2+

16. Learning Check A. Number of valence electrons in aluminum
1) 1 e ) 2 e- 3) 3 e-
B. Change in electrons for octet
1) lose 3e ) gain 3 e ) gain 5 e-
C. Ionic charge of aluminum
1) ) ) 3+

17. Solution A. Number of valence electrons in aluminum 3) 3 e-
B. Change in electrons for octet
1) lose 3e-
C. Ionic charge of aluminum
3) 3+

18. Learning Check Give the ionic charge for each of the following:
A. 12 p+ and 10 e-
1) 0 2) 2+ 3) 2-
B. 50p+ and 46 e-
1) 2+ 2) 4+ 3) 4-
C. 15 p+ and 18e-
2) ) 3- 3) 5-

19. Ions from Nonmetal Ions
In ionic compounds, nonmetals in 15, 16, and 17 gain electrons from metals
Nonmetal add electrons to achieve the octet arrangement
Nonmetal ionic charge:
3-, 2-, or 1-

20. Fluoride Ion     1 - : F  + e : F :     2-7 2-8 (= Ne)
unpaired electron octet
   
: F  e : F :
   
(= Ne)
9 p p+
9 e e-
ionic charge

21. Ionic Bond
Between atoms of metals and nonmetals with very different electronegativity
Bond formed by transfer of electrons
Produce charged ions all states.
Good Conductors if melted or dissolved
have high melting point.
Examples; NaCl, CaCl2, K2O

23. Ionic Bonds: One Big Greedy Thief Dog!

24. 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

26. Types of Ions Monoatomic ions – one atom ions
Polyatomic ions – ions made from more than one atom

27. COMPOUNDS FORMED FROM IONS
CATION +
ANION --->
COMPOUND
Na+ + Cl- --> NaCl
A neutral compound
requires
equal number of +
and - charges.

28. Predicting Charges on Monatomic Ions
KNOW THESE !!!!
Cd+2

29. Properties of Ionic Compounds Forming NaCl from Na and Cl2
A metal atom can transfer an electron to a nonmetal.
The resulting cation and anion are attracted to each other by electrostatic forces.

30. IONIC COMPOUNDS
NH4+
Cl-
ammonium chloride, NH4Cl

31. Some Ionic Compounds Mg2+ + N-3 ----> Mg3N2 magnesium nitride
Ca F- --->
CaF2
Mg N >
Mg3N2
magnesium nitride
Sn O >
SnO2
Tin (IV) oxide
calcium fluoride

32. Formulas of Ionic Compounds
Formulas of ionic compounds are determined from the charges on the ions
atoms ions
    –
Na  +  F :  Na : F :  NaF
   
sodium + fluorine sodium fluoride formula
Charge balance: = 0

33. Monatomic Ions

34. Writing a Formula
Write the formula for the ionic compound that will form between Ba2+ and Cl.
Solution:
1. Balance charge with + and – ions
2. Write the positive ion of metal first, and the
negative ion Ba Cl Cl
3. Write the number of ions needed as
subscripts BaCl2

35. Learning Check
Write the correct formula for the compounds containing the following ions:
1. Na+, S2-
a) NaS b) Na2S c) NaS2
2. Al3+, Cl-
a) AlCl3 b) AlCl c) Al3Cl
3. Mg2+, N3-
a) MgN b) Mg2N3 c) Mg3N2

36. Solution 1. Na+, S2- b) Na2S 2. Al3+, Cl- a) AlCl3 3. Mg2+, N3-
c) Mg3N2

37. CaCl2 = calcium chloride
Naming Compounds
Binary Ionic Compounds:
1. Cation first, then anion
2. Monatomic cation = name of the element
Ca2+ = calcium ion
3. Monatomic anion = root + -ide
Cl- = chloride
CaCl2 = calcium chloride

38. Naming Binary Ionic Compounds
Examples:
NaCl
ZnI2
Al2O3
sodium chloride
zinc iodide
aluminum oxide

39. Learning Check Complete the names of the following binary compounds:
Na3N sodium ________________
KBr potassium ________________
Al2O3 aluminum ________________
MgS _________________________

40. Transition Metals
Elements that can have more than one possible charge MUST have a Roman Numeral to indicate the charge on the individual ion.
1+ or or 3+
Cu+, Cu Fe2+, Fe3+
copper(I) ion iron(II) ion
copper (II) ion iron(III) ion

41. FeCl3 (Fe3+) iron (III) chloride
Names of Variable Ions
These elements REQUIRE Roman Numerals because they can have more than one possible charge:
anything except Group 1A, 2A, Ag, Zn, Cd, and Al
(You should already know the charges on these!)
Or another way to say it is: Transition metals and the metals in groups 4A and 5A (except Ag, Zn, Cd, and Al) require a Roman Numeral.
FeCl3 (Fe3+) iron (III) chloride
CuCl (Cu+ ) copper (I) chloride
SnF (Sn4+) tin (IV) fluoride
PbCl (Pb2+) lead (II) chloride
Fe2S (Fe3+) iron (III) sulfide

42. Examples of Older Names of Cations formed from Transition Metals (you do not have to memorize these)

43. Learning Check
Complete the names of the following binary compounds with variable metal ions:
FeBr2 iron (_____) bromide
CuCl copper (_____) chloride
SnO2 ___(_____ ) ______________
Fe2O3 ________________________
Hg2S ________________________

44. Polyatomic Ions
NO3-
nitrate ion
NO2-
nitrite ion

45. Polyatomic Ions
You can make additional polyatomic ions by adding a H+ to the ion!
CO3 -2 is carbonate
HCO3– is hydrogen carbonate
H2PO4– is dihydrogen phosphate
HSO4– is hydrogen sulfate

46. Ionic Nomenclature Writing Formulas
Write each ion, cation first. Don’t show charges in the final formula.
Overall charge must equal zero.
If charges cancel, just write symbols.
If not, use subscripts to balance charges.
Use parentheses to show more than one of a particular polyatomic ion.
Use Roman numerals indicate the ion’s charge when needed (stock system)

47. Ionic Nomenclature Sodium Sulfate Na+ and SO4 -2 Na2SO4
Iron (III) hydroxide
Fe+3 and OH-
Fe(OH)3
Ammonium carbonate
NH4+ and CO3 –2
(NH4)2CO3

48. Learning Check 1. aluminum nitrate a) AlNO3 b) Al(NO)3 c) Al(NO3)3
2. copper(II) nitrate
a) CuNO3 b) Cu(NO3)2 c) Cu2(NO3)
3. Iron (III) hydroxide
a) FeOH b) Fe3OH c) Fe(OH)3
4. Tin(IV) hydroxide
a) Sn(OH)4 b) Sn(OH) c) Sn4(OH)

49. Naming Ternary Compounds
Contains at least 3 elements
There MUST be at least one polyatomic ion
(it helps to circle the ions)
Examples:
NaNO3 Sodium nitrate
K2SO4 Potassium sulfate
Al(HCO3)3 Aluminum bicarbonate or
Aluminum hydrogen carbonate

50. Learning Check Match each set with the correct name:
Na2CO3 a) magnesium sulfite
MgSO3 b) magnesium sulfate
MgSO4 c) sodium carbonate
2 . Ca(HCO3)2 a) calcium carbonate
CaCO3 b) calcium phosphate
Ca3(PO4)2 c) calcium bicarbonate

51. Mixed Practice!
Name the following:
Na2O
CaCO3
PbS2
Sn3N2
Cu3PO4
HgF2

52. Mixed Up… The Other Way Write the formula: Copper (II) chlorate
Calcium nitride
Aluminum carbonate
Potassium bromide
Barium fluoride
Cesium hydroxide

53. COVALENT BOND bond formed by the sharing of electrons

54. Covalent Bond
Between nonmetallic elements of similar electronegativity.
Formed by sharing electron pairs
Stable non-ionizing particles, they are not conductors at any state
Examples; O2, CO2, C2H6, H2O, SiC

55. Covalent Bonds

56. Bonds in all the polyatomic ions and diatomics are all covalent bonds

57. when electrons are shared equally
NONPOLAR COVALENT BONDS
when electrons are shared equally
H2 or Cl2

58. 2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons.
Oxygen Atom
Oxygen Atom
Oxygen Molecule (O2)

59. when electrons are shared but shared unequally
POLAR COVALENT BONDS
when electrons are shared but shared unequally
H2O

60. Polar Covalent Bonds: Unevenly matched, but willing to share.

61. - water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.

62. METALLIC BOND bond found in metals; holds metal atoms together very strongly

63. Metallic Bond Formed between atoms of metallic elements
Electron cloud around atoms
Good conductors at all states, lustrous, very high melting points
Examples; Na, Fe, Al, Au, Co

64. Metallic Bonds: Mellow dogs with plenty of bones to go around.

65. Ionic Bond, A Sea of Electrons

66. Metals Form Alloys Metals do not combine with metals. They form
Alloys which is a solution of a metal in a metal.
Examples are steel, brass, bronze and pewter.

67. Formula Weights Formula weight is the sum of the atomic masses.
Example- CO2
Mass, C + O + O
43.999

68. Practice
Compute the mass of the following compounds round to nearest tenth & state type of bond:
NaCl;
= 58; Ionic Bond
C2H6;
= 30; Covalent Bond
Na(CO3)2;
23 + 2( x16) = 123; Ionic & Covalent