Tutorial 3B- Naming Chemical Compounds
The Periodic Table
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Arrangement of the elements in rows and columns
Horizontal rows are called periods
Vertical columns are called groups
Staircase separates metals (left) from non-metals (right)
Elements in the same group have similar properties
Example: Group 1 – Alkali Metals
Group 17 – Halogens
Group 18 – Noble Gases
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Elements in the periodic table have a unique chemical symbol
Element
Sodium
Potassium
Iron
Copper
Silver
Gold
Mercury
Antimony
Tin
Lead
Symbol
Na
K
Fe
Cu
Ag
Au
Hg
Sb
Sn
Pb
First letter always capital, second letter is always lowercase
You are responsible for the names/symbols of first 36 elements!!
Diatomic Molecules, Some elements occur naturally as diatomic molecules (
molecules composed of two atoms each):
H2(g) O2(g) N2(g) F2(g) Cl2(g) Br2(l) I2(s)
Ion Formation
-An ion is an electrically charged particles formed when electrons
are added or removed from an atom or molecule
-Ions typically form when metal atoms and non- metal atoms
approach each other
-Metal atoms lose electrons and non- metal gain these electrons
- Because the loss of electrons, the metal ion has a positive
charge; called a Cation
- Due to the gain of electrons, the non- metal ion has a
negative charge; called an Anion
Cations
• Main group metals usually form cations with a positive charge equal to the
group number. ( there are some exceptions):
Group 1A (Alkali Metals) – forms +1 cations Na+
Group 2A (Alkaline Earths) – form +2 cations Ca2+
Group 3A metals form +3 cations
Al3+
• Some transition metals can form more then one cation
Example: Fe2+ -> Iron (II)
Fe3+ -> Iron (III)
Cu+ -> Copper (I)
Cu2+ -> Copper (II)
Anions
• Non- metals form negative anions
Group 7A (Halogens) elements form -1 anions
Group 6A elements form -2 anions
Nitrogen (N) forms a -3 anion
ClO2N3-
Anion vs Cation
Anion
Examples
O2-), sulfide (S2-), fluoride
(F-), chloride (Cl-), bromide
(Br-), iodide (I-), nitride (N3-)
and hydride (H-)
Charges
Negative
Definition
An atom or a molecule
which is negatively
charged, i.e. has more
number of electrons than
protons.
Cation
sodium (Na+), Iron (Fe2+),
and Lead (Pb2+)
Positive
An atom or a molecule
which is positively
charged, i.e. has more
number of protons than
electrons.
Binary Compounds
Only 2 elements!!!
Binary Compounds: Molecular
( See Tro, pg 86-87)
(non- metal + non- metal)
** Main Rules**
 Cationlike element- same as the element
 anionlike element- change ending to ide
 Use prefixes to denote the number of each atom involved
For example, the name of B2Br4 is diboron tetrabromide
Number
1
2
3
4
5
6
7
8
9
10
Prefix
mono-
di-
tri-
tetra-
penta-
hexa-
hepta-
octa-
nona-
deca-
• When the anion name begins with a vowel, the last a or o on the
prefix is dropped. For example, the name of N2O4 is dinitrogen
tetroxide.
• The prefix mono is not used for the atom named first. For example,
the name NO2 is nitrogen dioxide
Binary Compounds: Ionic ( metal cation + non-metal anion)
See Tro, pg 83-85
-These compounds consists of monatomic cations (matals) and
monatomic anions (non-metals)
-Name the cation first
-Name the anion and change the ending to “ide”
**Main Rules**
 Cation- same as the element
 Anion- change ending to ide
For example, the name NaCl is sodium chloride.
When writing a formula from a name, we need to determine the symbol/formula
of each ion, and its charge. Use the subscripts to produce an electrically
neutral formula( the total positive charge must equal the total negative
charge)
For example, the formula of magnesium chloride is MgCl2
1.
Main group metals usually form cations whose charge is equal to
the group number( exceptions exist)
a)
Group 1 elements form +1 cations (M+); Group 2 elements form
+2 cations (M2+)
Silver (Ag), Zinc (Zn), Cadmium (Cd), Aluminum (Al), and
Scandium (Sc) dependably form these cations:
Ag+, Zn2+, Cd2+, Al3+, and Sc3+
Other metals tend to form more then one cation, especially
transition metals. See pg 100 in lab manual for elements that form
cations with varying charges. In naming these cations, we should
use a roman numeral in parentheses to indicate the number of
charges
b)
c)
2)
Main Group nonmetals usually form anions.
a)
In binary ionic compounds, group 17 elements form -1 anions,
and group 16 elements form -2 anions
In binary ionic compounds, nitrogen forms -3 anions
b)
Compounds with Polyatomic Ions (See Tro, pg 85)
Metal cation + polyatomic anion
BaSO4
Barium sulfate
polyatiomc cation + non-metal anion
polyatomic cation + polyatomic anion
(NH4)2S ammonium sulfide
NH4NO3 ammonium nitrate
Acids: H____(aq)
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A compound is an acid when it is ionic, has a H+ as the cation and is
dissolved in water
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There are two main types:
1)
2)
Non-Oxygen Containing acids
- If the compound would be named as hydrogen ____ide, change the
name to hydro ____ic acid.
- Ex. HCL Hydrogen Chloride Hydrochloric Acid
Oxygen Containing acids (oxoacids)
- If the polyatomic ion ends in “ate”, change the ending to “ic” and add
“acid”
- If the polyatomic acid ends in “ite”, change the ending to “ous” and
add “acid”
Example. HNO3(aq) nitric acid
*comes from nitarte ion*
HNO2(aq) nitrous acid
*comes from nitrite ion*
Hydrates: ____ H2O
• A hydrate is an ionic compound with a number of water molecules
weakly bonded to it
• To name:
– Name the ionic compound before as normal
– Choose the prefix corresponding to the number of water molecules,
then add “hydrate”
Example, LiCl ·H2O
Lithium Chloride Monohydrate
CoCl2 ·6H2O Colbalt Chloride Hexahydrate