Post on 16-Dec-2015
Bonding & Stability Atoms want to be stable. The Octet Rule states that a chemically stable
atom contains 8 valence electrons.
Chemical Bonds Atoms will gain, lose, or share electrons to obtain 8
valence electrons – this is called a chemical bond There are 3 types of bonds:
Metallic Ionic Covalent / Molecular
Types of Compounds1. Ionic Compounds:- involve the transfer of electron(s) between 2
oppositely charged ions (cation and anion)- metal and a nonmetal or a combination involving a
complex ion- forms an ionic bond - exists as an ionic crystal lattice (not individual
molecules)- known as a formula unit (eg. A formula unit of salt,
not a molecule)
Formula Unit a chemical formula showing the simplest
whole number ratio of cations to anions in an ionic compound.
Eg. NaCl – sodium chloride
Types of Compounds (continued)2. Molecular compounds:
- involve the sharing of electrons between nonmetals
- forms a covalent bond- exists as individual molecules- Eg. Carbon dioxide CO2
water H2O
Properties of Ionic and Molecular Compounds
1. State at room temperature:- all ionic compounds are solids- molecular compounds may be a solid, liquid or a gas
2. Conductivity of solution:- ionic compounds conduct electricity (electrolytes)- molecular compounds do not conduct electricity (non- electrolytes)
3. Solubility in water:- ionic compounds are soluble, to varying degrees (some better than others) and form colored or colorless solutions.- molecular compounds may or may not be soluble (colorless solutions if they form).
Nomenclature Chemical nomenclature is the systematic
naming of chemical compounds. Science 1206 examines the naming of ionic
compounds, molecular compounds and acids. Compounds can be divided into two basic
categories, those which are true binary compounds (contain only two types of elements), and those which contain more than two different types of elements.
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Ionic compoundsIdentify the type of ions:
A. Monoatomic or simple ions
B. Polyatomic or complex ions
C. Multivalent ions
D. Hydrates
Rules for Naming ionic compounds:
A. Monoatomic or simple ions Single atoms that have lost or gained one or
more electrons Form binary ionic compounds (2 simple ions) Consist of cations and anions Eg. Sodium + chlorine Na+ Cl-
Cations are written first, anions are second (name changes to “-ide” for the anion)
The total charge must be zero Do not write charges in your final answer
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Rules:
b. Determine the lowest whole number ratio of ions which will provide an overall net charge of zero
Ag1+ Cl1- becomes AgCl
(silver chloride)
Practice – Writing FormulasWrite formulas for the following compounds:
Lithium bromide
Potassium chloride
Barium chloride
Magnesium nitride
Aluminum Fluoride
Calcium Nitride
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Naming Ionic Compounds Cation is named first Anion is named second Ending of anion is changed to “ide”
Practice:
NaCl BaCl2 Al2O3
B. Multivalent ions
- certain transition metals can form more than one type of ion, each with a different charge.
- eg. Cu2+ - copper (II)
Cu+ - copper (I)
Multivalent ions (continued) The transition metals have various electron
configurations that will make them stable Use a roman numeral after the cation to
specify its charge (Stock naming system). Eg. Iron (ii) oxide FeO
Iron (iii) oxide Fe2O3
Stock vs. ClassicalFormula Stock Name Classical Name Cu+ copper(I) ion Cuprous ion Cu2+ copper(II) ion Cupric ion Fe2+ iron(II) ion Ferrous ion Fe3+ iron(III) ion Ferric ion
C. Polyatomic/Complex Ions Polyatomic ion: atoms of 2 or more elements
covalently bonded together with an overall chargeeg. Nitrate NO3
-
Ammonium NH4+
Complex ions are groups of atoms that are made stable by sharing electrons and which then become even more stable by gaining (usually) or losing electrons.
The total positive charge in the formula must be equal to the total negative charge.
Rules: Name the cation, then name the anion Don’t change the ending of a polyatomic ion! Balance the charges If you need more than 1 complex ions, use
brackets for that group
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Hydrate - Rules Name the ionic part of
the formula first Name the water part
second using a prefix system for the number of water molecules
Add prefix to “hydrate”
Prefixes:
1. mono
2. di
3. tri
4. tetra
5. penta
6. hexa
7. hepta
8. octa
9. nona
10. deca
Review1. Silver nitrate 12. Copper(II) sulfate2. Iron(II) phosphate 13. Cobalt(II) iodide3. Chromium(III) oxide 14. Cesium phosphate4. Nickel(II) fluoride 15. Magnesium acetate5. Copper(I) nitrate heptahydrate 16. Potassium oxide6. Lead(II) carbonate 17. Strontium nitrate7. Iron(II) fluoride 18. Aluminum sulfate8. Iron(III) hydroxide 19. Calcium chlorate9. Zinc phosphate dihydrate 20. Rubidium cyanide10. Potassium chlorate 21. Tin(IV) oxide11. Ammonium chromate 22. Titanium(II) iodide
Ionic Formulas1. BaCl2 10. FeCl3
2. Pb(NO3)2 11. Ca(CN)2
3. TiI3 12. Cu2S
4. K2CrO4 14. Cd(ClO)2
5. CoO 15. SnO2
6. Mg(ClO4)2 16. NaHCO3
7. CuSO4 17. Al(C2H3O2)3
8. Na2SO3 18. Ni3(PO4)2
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Is there a metal or ammonium in the formula?
Binary molecular compounds form between 2 non-metals
Covalent bonds: shared electrons Molecular formula: shows number and kind
of atoms in a molecule
Naming Use prefixes to specify
number of atoms of each element in the molecule
Second element ends with “-ide”
No charges used in formula The prefix “mono-” should
not be used on the first element
1. mono
2. di
3. tri
4. tetra
5. penta
6. hexa
7. hepta
8. octa
9. nona
10. deca
Practice Name the following:
NO CO2
N4O9
N6O
Write formulas for the following: Boron trifluoride Sulfur hexafluoride Nitrogen monoxide Phosphorous
pentachloride
ACIDS HCl Hydrochloric Acid H2SO4 Sulfuric Acid
HNO3 Nitric Acid
HC2H3O2 Acetic Acid
H3PO4 Phosphoric Acid
H2CO3 Carbonic Acid
Acids have 2 criteria:1. They must contain hydrogen (H+)
2. They must be dissolved in water (aqueous); the formula will always contain the subscript aq.