1. Unit 7: Bonding and Naming

2. A Quick Review… Atoms are electrically neutral Ions Anion Cation
Charged particles
Anion
Negative ion; gain electrons; nonmetals
Cation
Positive ion; lose electrons; metals

3. Unit 7 Objectives:
Distinguish between ionic, covalent, and metallic bonds
Distinguish between ionic and molecular compounds
Name ionic and molecular compounds
Write formulas for ionic and molecular compounds

4. Bonds
A valence electron from one atom is attracted to another atom’s nucleus
Remember…
Everything wants a full valence shell
Everything wants to have lower Kinetic Energy
Can tell the type using the atoms’ electronegativities, or by the type of atoms involved

5. Ionic Bonds Electrons are donated from one atom to the other
Very different electronegativities (difference is >1.7)
One atom is MUCH more attracted to electrons than the other
Which types of atoms are involved?
Metals and non-metals – the metal gives up electrons to the nonmetal

6. Covalent Bonds Electrons are “shared” by two atoms
Similar electronegativity values (difference < 1.7)
Closer electronegativities means more equal sharing
What types of atoms are involved?
2 nonmetals

7. Covalent Bonds Atoms always share pairs of electrons Type of Bond
Pairs Shared
Electrons Shared
Single 1 2
Double 4
Triple 3 6

8. Metallic Bonds What type of atoms? 2 metals
Metal cations surrounded by a “sea of electrons”

9. Determine the Bond Type
H-O
H-Cl
Na-Cl
K-Cr
Na-Br
C-H

10. Types of Compounds - Ionic
Ionic Compounds
Contain ionic bonds
Electrically Neutral
A metal is joined to a non-metal or a polyatomic ion
Polyatomic Ion
An ion made up of more than one element
Covalently Bonded
Almost always anions
Ex: SO42-

11. Types of Compounds - Ionic
Law of Definite Proportions
Small whole number ratios
The formula represents a formula unit (NOT a molecule)
Formula Units are always simplest ratio (REDUCE!)
Ions surround each other so you can’t see which is hooked to which

12. Types of Compounds - Molecular
Contain covalent bonds
Non-metals are joined to other non-metals
Called molecules
Smallest electrically neutral unit that still maintains the properties of the substance
Can be one type of atom – O2
Can be a compound – CO2

13. Distinguishing Between Ionic and Molecular
Bond Type
Covalent
Smallest Piece
Formula Unit
Molecule
Types of Elements
Metal-Nonmetal
Metal –Polyatomic Ion
Nonmetal - Nonmetal
State of Matter
Solid
Solid, liquid, or gas

14. Chemical Formulas
Show the kind and number of each type of atom in a compound
For molecules you can also say molecular formula
Subscripts are used to tell you if there is more than one of an atom. If there is only one, no subscript.
NaCl, BaS
CaCl2, C6H12O6

15. Diatomic Elements Some elements are never found as a single atom
If they aren’t bonded to another type of atom, they bond to themselves
There are 7:
Hydrogen (H2)
Nitrogen (N2)
Oxygen (O2)
Fluorine (F2)
Chlorine (Cl2)
Bromine (Br2)
Iodine (I2)

16. Oxidation State Remember the trend for the representative elements
Transition Metals don’t always have the same oxidation state

17. Naming Ions Two methods
Classical Method – uses root word (in Latin) + suffixes (-ous, -ic).
Fe2+ = Ferrous
Doesn’t give the true value
Doesn’t work for everything
Stock System – uses Roman numerals in ( ) to indicate the numerical value.
Fe2+ = Iron (II)
Much better because it works all the time. We’ll use this one

18. Roman Numerals No, you don’t get these on the test…
Use with transition metals
Number
Roman Numeral 1 I 2 II 3
III 4 IV 5 V 6 VI 7
VII 8
VIII 9 IX 10 X

19. Naming Ions - Cations Use the stock system
If the charge is always the same (representative elements, Cd, Ag, Zn), just say the name of the element followed by “ion”
Example: Ca2+ = calcium ion
If it is a metal that varies (transitions, Sn, Pb) say the name of the element, the oxidation state as a Roman Number, followed by “ion”
Example: Mb2+ = molybdenum (II) ion

20. Naming Ions: Exceptions
Representative elements that need Roman Numerals Pb Sn
Transition metals that no not need a Roman Numeral (bc they always have the same oxidation state)
Ag1+
Cd2+
Zn2+

21. Naming Ions - Cations Write the name of each cation Na1+ Ca2+ Al3+
Li1+
Pb2+
W6+

22. Writing Formulas- Cations
Write the formula for each ion.
Potassium Ion
Magnesium Ion
Copper (II) Ion
Silver Ion
Mercury (II) Ion
Chromium (VI) Ion
Barium Ion

23. Naming Ions - Anions
Anions always have the same oxidation state (no need for Roman Numerals)
Change the ending of the element to –ide
Ex: F = Fluorine
F - = Fluoride Ion

24. Naming Ions - Anions Name the following ions Cl 1- N 3- Br 1- O 2-
Ga 3+

25. Writing Formulas - Anions
Write the formula for each ion
Sulfide Ion
Iodide Ion
Phosphide Ion
Strontium Ion

26. Polyatomic Ions Ions containing more than 1 element
Almost always anions
See list on the back of your Periodic Table or Packet
No, You need not memorize them
To name them, just check the list and use the name. No change to the ending

27. Naming Ionic Compounds
Binary Compounds only have 2 elements
To write the name, just name the 2 ions
NaCl - sodium chloride
MgBr2 – magnesium bromide

28. Naming Binary Ionic Compounds
A little harder with transition metals…
Don’t forget the Roman numerals
Ex: CuO
Overall, the compound is neutral
We know O is 2-
Copper must be 2+
Copper (II) Oxide
Ex: CoCl3
We know Cl is 1- and there are 3 of them
That makes 3-
Co must be 3+
Cobalt (III) Chloride

29. A Few More Examples Cu2S Fe2O3 Sulfur is always:
The Copper needs to add up to:
There are 2 Copper atoms, so each one is:
Name:
Fe2O3
Oxygen is always:
There are 3 of them, which adds up to:
The 2 Iron atoms should add up to:
Each Iron is then:

30. Name some Binary Ionic Compounds
KCl
Na3N
CrN
Sc3P2
PbO
PbO2
Na2Se

31. Naming Ternary Ionic Compounds
These have polyatomic ions. Name the cation, then name the polyatomic ion
Ex: NaNO3
Na = Sodium
NO3 = Nitrate
Sodium Nitrate
The hardest part is remembering to check your list!

32. Name the Ternary Ionic Compounds
LiCN
Fe(OH)3
(NH4)2CO3
NiPO4

33. Writing Formulas for Ionic Compounds
Remember, charges add up to ZERO
Get the oxidation state of each piece
Balance charges out by adding subscripts
Polyatomic ions need ( ) if there is more than 1 of it
Use the criss-cross method
Make the oxidation state of one the subscript of the other. Like finding the least common multiple.
Calcium Chloride Ca2+ Cl 1-
CaCl2

34. Write the formulas for these
Lithium Sulfide
Tin (II) Oxide
Tin (IV) Oxide
Magnesium Fluoride
Copper (II) Sulfate
Iron (III) Phosphide
Gallium Nitrate
Iron (III) Sulfide
Ammonium sulfide

35. Keep in Mind…
If you see ( ) it’s telling you the oxidation state of the cation
Anions generally end in –ide if it’s an element, and –ate or –ite if it’s a polyatomic ion

36. Molecular Compounds Made of only Non-metals
Electronegativities are similar, they aren’t being held together by opposite charges
This means we can’t use the oxidation state to see how many of each atom we have
The name will tell you the amount of each atom using prefixes

37. Prefixes Yes, memorize these!! 1 Mono 2 Di 3 Tri 4 Tetra 5 Penta 6
Hexa 7
Hepta 8
Octa 9
Nona 10
Deca
Yes, memorize these!!

38. Naming Molecular Compounds
To write the name:
Prefix + first element then Prefix + second element
Only one exception this time: if the prefix on the first element is “mono” we don’t write it
No double vowels (oa, oo)
Rule of thumb: if it sounds weird, you need to drop a vowel

39. Name the Molecular Compounds
N2O
NO2
Cl2O7
CBr4 CO
BaCl2

40. Write the Formulas for Molecular Compounds
Diphosphorous pentoxide
Tetraiodide nonoxide
Sulfur hexafluoride
Nitrogen trioxide
Carbon trtrahydride
Phosphorous trifluoride
Aluminum chloride

41. Naming Acids
We will save the nomenclature for acids until we start talking about them.
For now, here are a couple you should know:
Acid
Formula
Hydrochloric acid
HCl
Sulfuric Acid
H2SO4
Acetic Acid
CH3COOH