1. Covalent Bonding
Physical Science

2. Covalent Bonding Covalent bonding
Compounds composed only of anions (negative nonmetals) share electrons in covalent bonds.
Bonding in which e- are shared.
Each atom fills up its valence shell w/ shared e-.
Sharing 1 pair of e- = single bond
2 pairs of e- = double bond
3 pairs of e- = triple bond

3. Properties of Covalent compounds
ELECTRONS ARE SHARED
BETWEEN NONMETALS
low melting points
do not break into ions / do not dissolve

4. Properties of Covalent compounds
poor conductors of electricity
liquid or gas at room temperature

5. Properties of Covalent compounds
can be polar or nonpolar
Amorphous solids – not arranged in a regular repeating pattern

6. Molecules Molecule Combo of atoms formed by covalent bonds.
Not made of ions!

7. Ball-And-Stick Models
Atomic Centers
Shared Pairs of Electrons

8. MORE ABOUT COVALENT MOLECULES
Monatomic Molecule– exist as single atoms (noble gases like He and Ne)
Diatomic Molecule – a molecule consisting of two atoms of the same element (O2, F2)
They can have double, single and triple bonds.
There are only 3 molecules that form triple bonds – Carbon, Nitrogen, and Phosphorus

9. Diatomic Elements Diatomic elements
Never exist alone as single atom.
Always bonded covalently.
Seven diatomic elements (know these!):
Hydrogen = H2 Oxygen = O2
Chlorine = Cl2 Iodine = I2
Nitrogen = N2 Fluorine = F2
Bromine = Br2

10. Diatomic Elements Remember: Mr. BrINClHOF
(pronounced “brinklehoff”)
You will always have a molecule of each of these elements instead of a single atom.

11. Diatomic Elements

12. NOT ALL COVALENT BONDS ARE EQUAL
Nonpolar Covalent Bond
atoms in the bond pull equally (especially identical atoms), and share electrons equally.

13. NOT ALL COVALENT BONDS ARE EQUAL
Polar Covalent Bond
electrons are shared unequally.
One atom wants the electrons really badly but isn’t strong enough to pull them away.
It holds the electrons closer and is slightly negative.
The other atom has a slightly positive charge.

14. Polar Covalent Bonding
A perfect example of a polar covalent molecule is water.

15. Weird example time!

16. Little Dog and Big Dog both have strong grips and they like to share dog bones.

17. Little Dog and Big Dog both have strong grips and they like to share dog bones. Sharing dog bones is like a covalent bond.

18. When 2 Big Dogs share a bone, they share…

19. When 2 Big Dogs share a bone, they share equally – nonpolar covalent
Because the 2 Big Dogs are the same –
they represent a diatomic molecule

20. 2 Little Dogs share a bone =
DIATOMIC MOLECULE – 2 of the same elements sharing

21. 2 Little Dogs share a bone = share equally. (nonpolar, diatomic)
DIATOMIC MOLECULE – 2 of the same elements sharing

22. When Big Dog and Little Dog share a bone…

23. Big Dog has a stronger pull on the bone and the dogs share unequally – polar covalent bond

24. Each bone represents a PAIR of electrons.

25. Big Dog and Little Dog can share 1, 2, or 3 bones.
SINGLE COVALENT BOND
DOUBLE COVALENT BOND
TRIPLE COVALENT BOND

26. Naming Molecules Very simple!
Look at subscripts and elements in formula.
1st element: prefix (if subscript > 1) + element
2nd element: prefix + element ending in –ide.
Prefixes:
1 = mono
2 = di
3 = tri
4 = tetra
5 = penta
6 = hexa
7 = hepta
8 = octa
9 = nona
10 = deca

27. The second element ends in –ide.
Octa- 8
Hepta- 7
Hexa- 6
Penta- 5
Tetra- 4
Tri- 3
di- 2
Mono- 1
Prefix to use
Number
COVALENT PREFIXES
If it is two negatives, the bond is covalent and you use prefixes to indicate the number of elements in the compound.
The second element ends in –ide.

28. Examples CS2 = carbon disulfide CO = carbon monoxide
N2F4 = dinitrogen tetrafluoride
P2S6 = diphosphorus hexasulfide
BrF = bromine monofluoride
P4O10 = tetraphosphorus decoxide

29. Carbon monoxide Sulfur dioxide CO SO2 Octa- 8 Hepta- 7 Hexa- 6 Penta-5
Tetra- 4
Tri- 3
di- 2
Mono- 1
Prefix to use
Number
COVALENT PREFIXES CO
Carbon monoxide
SO2
Sulfur dioxide

30. Phosphorus pentaiodide
Octa- 8
Hepta- 7
Hexa- 6
Penta- 5
Tetra- 4
Tri- 3
di- 2
Mono- 1
Prefix to use
Number
COVALENT PREFIXES
N2O3
Dinitrogen trioxide
PI5
Phosphorus pentaiodide

31. Practice CCl4 N2O carbon tetrachloride SF6 dinitrogen monoxide
sulfur hexafluoride

32. One Final Note
The final vowel in prefixes is often dropped for oxygen.
Example: CO = carbon monoxide
NOT: carbon monooxide
Except when the prefix ends in “i”
Example: SO3 = sulfur trioxide

33. Ionic Vs Covalent Compounds
Ionic and covalent cmpds are alike b/c:
Formed from 2 or more atoms bonding together.
Atoms more stable w/ 8 val. e-.

34. Ionic Vs Covalent Compounds
Ionic and covalent cmpds are diff. b/c:
Ionic cmpds = metal + nonmetal
Covalent cmpds = nonmetal + nonmetal
Ionic cmpds  transfer of e-
Covalent cmpds  sharing e-
Ionic cmpds  not named using prefixes
Covalent cmpds  named using prefixes

35. Ionic Vs Covalent Compounds
Ionic and covalent cmpds are diff. b/c (cont.)
Ionic cmpds do not form separate molecules.
Covalent cmpds do form molecules.
Ionic cmpds = high melting temps.
Covalent cmpds = low melting temps.
Ionic cmpds = conduct elec. current when dissolved in H2O. (electrolytes)
Covalent cmpds = do not conduct elec. current when diss. in H2O (non-electrolytes)

36. Comparison Chart IONIC COVALENT transferred from metal to nonmetal
shared between nonmetals
Electrons
Melting
Point
high
low
Soluble in
Water
yes
usually not
yes (solution or liquid)
Conduct Electricity no
crystal lattice of ions, crystalline solids
molecules, odorous liquids & gases
Other
Properties

37. Metallic Bonding Metallic bonding Bond formed b/w metal atoms.
“Sea of electrons”
e- flow freely through metal sample.
This is why metals:
are good conductors
have high melting points
are flexible

38. Metallic Bonding 1. Solids (s) at room temperature
ELECTRONS ARE SHARED IN A COMMON “POOL” OR “SEA”
BETWEEN POSITIVE METAL NUCLEI
1. Solids (s) at room temperature
2. High melting and boiling points
3. Good conductors of heat and electricity
4. Malleable and ductile

39. Alloys Alloys Hom. mix. of metals. Held together by metallic bonds.
Have properties of metals.
Examples:
Gold alloy = Au + Ag, Cu, Ni, or Zn
Bronze = copper + tin
Brass = copper + zinc
Steel = iron + carbon
Stainless steel = Fe + Cr + a little C
Aluminum alloy = Al + Mg, Mn, or Cu

40. Types of Bonds Predicting bond type: B/w metal & nonmetal = ionic bond
B/w nonmetal & nonmetal = covalent bond
B/w metal & metal = metallic bond

41. Let’s review! Two positives (++) DO NOT BOND.
Two negatives (- -) will form a covalent bond.
The name is determined using prefixes.

42. Let’s review! A positive and a negative (+ - )make an ionic bond.
Charges need to be crisscrossed to get the formula.
To name it, say the cation first (with roman numerals if it is a DFP metal) and then the anion with –ide.

43. Let’s review! Roman numerals are ONLY for Transition metals.
Prefixes are ONLY for
covalent.
Crisscrossing is ONLY for
Ionic.

44. Au 2+ and AS 3- Rb 1+ and Br 1- S 2- and Se 2- P 3- and I 1-
PRACTICE BONDING
Au(II) and As
Au 2+ and AS 3-
IONIC
Au3As2
S and Se
S 2- and Se 2-
Covalent
SSe
Rb and Br
Rb 1+ and Br 1-
IONIC
RbBr
P and I
P 3- and I 1-
Covalent
PI3