UNIT 5 NOMENCLATURE
CH. 6
There are approx. 100 elements but millions of compounds.
≈ 100,000 Ionic (Inorganic) Cpds.
> 4, 000, 000 Molecular (Organic) Cpds.
Only the 6 noble gases like Ne & He do not form cpds.
Compound (cpd.) – a chemical combination of atoms of 2 or more elements; where elements have lost, gained
or shared electrons
Alloy – a physical combination of metals made by melting them together, ex. Sterling silver, stainless steel,
brass, etc.
THE FOLLOWING INFORMATION IS EXTREMELY IMPORTANT!! IT
IS THE FOUNDATION OF ALL CHEMISTRY!!
2 Kinds of Compounds
Molecular
Ionic
1. Combination of 2 or more nonmetals
1. Combination of 1 metal and 1 or more nonmetals
2. Covalently bonded – electrons shared
2. Ionically bonded - metals lose e-‘s and
nonmetals gain e-‘s
3. Molecule is the base unit
3. Ion is the base unit.
4. Ex. – CO2, H2O, NH3, C6H12O6
4. Ex. – NaCl, Fe2O3, NaHCO3
carbon dioxide, water, ammonia, glucose
sodium chloride, rust, baking soda
5. Named with prefixes
5. Name metal ion, then nonmetal ion
6. Low melting point –
O2(-218oC), H2O (0 oC)
6. High melting point –
NaCl (801 oC)
7. Most are gases or liquids at room temp.
7. Most are crystalline solids (salts) at room temp.
Molecule – smallest electrically neutral unit of a substance that still has the properties of that substance
Octet rule – atoms react by gaining, losing, or sharing electrons so as to acquire the stable electron
structure of a noble gas, usually 8 electrons
Sugar and Salt Conductivity Demonstration
Ionic
Compounds
Metal &
Nonmetal
Ionic Bonding
Ions
Electrolytes
Salts
Molecular Compounds
All Nonmetals
Covalent Bonding
Molecules
Nonelectrolytes
Sugars, Fats, Alcohols, Oils,
Carbohydrates, etc.
Electrolyte – a compound that conducts electricity in aqueous solution
Nonelectrolyte – a compound that does not conduct electricity in aqueous solution
SUPER IMPORTANT!!!
THE GROUP # TELLS YOU THE NUMBER OF VALENCE ELECTRONS
(THE ONES IN THE OUTERMOST SHELL INVOLVED IN BONDING)
The group number will tell you all about how an element will bond and the number of electrons it loses, gains
or shares.
***For metal in groups 1A & 2A only: group # = ionic charge
To name metal ions use the element name followed by the word ion.
Ex. Na+ sodium ion
Mg+2 magnesium ion
***For nonmetals above the stair step but not touching it: group # - 8 = ionic charge
To name nonmetal ions, use the root of the element with –ide ending followed by ion.
Group 5 – 8 = -3
N-3 nitride ion
P-3 phosphide ion
Group 6 – 8 = -2
O-2 oxide ion
S-2 sulfide ion
Se-2 selenide ion
Group 7 – 8 = -1
F- or F-1fluoride ion
Cl- or Cl-1chloride ion
Br- or Br-1 bromide ion
Ior I -1 iodide ion
II-
MEMORIZE THE FOLLOWING:
Diatomic (2 atoms) Molecules: H2, N2, O2, F2, Cl2, Br2, I2
Called: hydrogen gas, nitrogen gas, oxygen gas, fluorine gas, chlorine gas, bromine gas and iodine gas
Triatomic (3 atoms) Molecule: O3 ozone which, of course, absorbs UV rays from sun
Ionic Cpds.
Ions – atoms or groups of atoms that have a charge due to the loss or gain of electrons
Metals – lose electrons to form cations (+)
Nonmetals – gain electrons to form anions (-)
Polyatomic (Many atoms) ions – groups of atoms that behave as a unit and carry a charge
Ex. PO4-3 phosphate, SO4-2 sulfate, NO3- nitrate
**Mother nature changes elements into ions to achieve stability.
The noble gases are the most stable elements because of their full outer shell of electrons. All the other
elements react in such a way as to make their electron configuration like the noble gases, i.e. they imitate
the noble gases by losing, gaining or sharing electrons
Group 4A Elements are not usually found in Ionic Compounds because:
For Group 4A Elements C & Si, they don’t know whether to lose 4 electrons or gain 4 electrons so they
share electrons instead, covalently bonding forming molecular compounds.
Chemical Nomenclature – a naming system for chemicals based on IUPAC rules
IUPAC – International Union of Pure and Applied Chemistry
A Elements – Representative, follow rules and exhibit properties similar to other elements in the same
group
A Elements include: alkali metals, alkaline earth metals, nonmetals (above stair step) and noble gases
B Elements – Misbehavers, have properties between metals and nonmetals, so they have many exceptions
to the rules
B Elements include: transition metals, inner transition metals, metalloids
B Elements (Misbehavers) that only form one ion: Ag+, Zn+2, Cd+2, Al+3
Group # = charge
**IMPORTANT: ALL CPDS. HAVE A CHARGE OF ZERO!
Binary cpds. Contain 2 elements
Binary Ionic Cpds. – contain 1 metal and 1 nonmetal
**SUPER IMPORTANT!!
Roman Numerals are only used to indicate the charge of Misbehavers (ions that form more than one
charge). They are not used for elements like Na or Ca that are representative.
The Front half of an ionic cpd is always a + metal
The Back half of an ionic cpd is always a – nonmetal
You can always figure out the charge of the back half from the front half
SnO → 1Sn+2 + 1O-2 tin (II) or stannous oxide
Mn2S3 → 2Mn+3 + 3S-2 manganese (III) or manganic sulfide
2 Ways to do a formula:
1. Write a formula from a name
2. Write a name from a formula
Ex. From a name:
Sodium Fluoride
Na+ + F- → NaF
Iron (III) Oxide
2Fe+3 + 3O-2 → Fe2O3
Ex. From a Formula:
KF → K+ + FPotassium fluoride
CaCl2 → Ca+2 + 2FCalcium fluoride
Parentheses are only used on polyatomic ions when there is more than one of them.
Ex. w/out parentheses
NaNO3 → Na+ + NO3Sodium nitrate
Ca(NO3)2 → Ca+2 + 2NO3Calcium nitrate
Hydroxide (OH-), Cyanide (CN-) and ammonium (NH4+) need parentheses also when there is more than
one of them.
Fe(OH)3
Ca(CN)2
(NH4)3PO4
Acids – cpds that give off H+ when dissolved in water
Bases – cpds that give off OH- when dissolved in water
Water is neutral because it dissociates into equal parts of acid and base
1H2O → 1 H+ + 1 OHequal parts of acid and base
pH = -log[H+]
pH scale 0 >>>>>>>>>>>7>>>>>>>>>>>14
acid
base
**RECOGNIZE AN ACID BY SEEING THE H ON THE FRONT!!
General Formula is HX where X is a monatomic or polyatomic anion
Name an acid by looking at the anion (negative, back half)
If anion ends in:
Then acid name is:
-ide
hydro_____ic acid
-ite
_____ous acid
-ate
_____ic acid
HCl → H+ + Cl- anion is chloride so acid name is hydrochloric acid
H2SO3 → 2H+ + SO3-2 anion is sulfite so acid name is sulfurous acid
H2SO4 → 2H+ + SO4-2 anion is sulfate so acid name is sulfuric acid
**IONIC CPD. NOMENCLATURE SUMMARY:
To write a formula from a name:
1.
2.
3.
4.
5.
Find element on periodic table.
Write down symbol and charge of metal and nonmetal
Balance charges using coefficients if needed.
Coefficients become subscripts in formula.
Remember, there are no charges in a formula.
To write a name from a formula:
1.
2.
3.
4.
5.
Break up formula into ions with correct charges.
Subscripts become coefficients.
If misbehaver, figure out back half charge first.
Name each ion.
Write stock and classical name if it is an ion with more than one charge (misbehaver).
**MOLECULAR CPD. NOMENCLATURE:
1.
2.
3.
4.
5.
The cpd will have only 2 nonmetals.
There are no charges and no reactions to show.
No mono- or –ide on 1st element.
Put –ide on root of 2nd element.
Use prefixes to indicate subscripts.
Molecular Prefixes:
Naming Molecular Cpds.
1st
Element
No monoNo-ide
Use
prefixes
1 – mono
2 – di
3 – tri
4 – tetra
5 – penta
6 – hexa
7 – hepta
8 – octa
9 – nona
10 - deca
2nd
Element
Use monoUse - ide
Use
prefixes