Transcript nomenclature pptx

Nomenclature
Writing and Naming Chemical Compounds
What’s a Compound?
NOTES 1: Compounds and Their Formulas
• Compounds have been defined as matter formed by two or more
different elements joined by a chemical bond.
• Formulas allow scientists to identify the composition of compounds. Every
formula contains the symbols of elements that make up the compound.
One example is NaCl, also known as table salt, is formed when sodium (Na)
and chlorine (Cl) combine in a chemical reaction.
NaCl
What does a formula “tell” you?
Baking soda, or sodium bicarbonate, has a more complicated formula, NaHCO3.
Baking soda is formed when sodium (Na), hydrogen (H), carbon (C), and
oxygen (O) combine in a chemical reaction. The small number 3 in the formula is
called a subscript.
A subscript shows the number of atoms of an element in a compound.
The subscript always refers to the symbol just before it in the formula.
If there is no subscript following a symbol, it means there is only one of that
kind of atom in the molecule.
Example: Baking soda thus contains, ____________ atom of sodium, _____
atom of hydrogen, _____ atom of carbon, and ______ atoms of oxygen in
each molecule.
A molecule is the term used for any bonded elements.
NaHCO3
Identify the following substances:
oxygen
oxygen
hydrogen
hydrogen
carbon
Carbon
monixide
aluminum
Ammonia
chlorine
gold
Carbon
dioxide
Compounds
Video Clip: Why it Matters
Warm up
Label the following as element or
compound:
CO
O2
Li
Cl2
NaCl
NOTES 2: VALENCE ELECTRONS, LEWIS
DOT DIAGRAMS, AND
OXIDATION NUMBERS
Review: Bohr’s Electron
Model
1. How many total electrons are in a
neutral atom of Sulfur?
2. How many electrons are in
sulfur’s highest energy level (it’s
most outer shell)(HINT: use the
picture to the right)?
3. How many electrons does sulfur need to gain
or lose in order to have 8 valence electrons
(electrons in the outermost shell)?
Recap: Bohr’s Electron Model
Bohr developed an atomic model in which the
electrons are arranged in specific energy levels.
The lowest level (n=1) is located closest to the
nucleus. The highest level is located farther away
from the nucleus.
Recap: Bohr’s Electron Model
*The electrons in the highest energy level for any
element are known as valence electrons.*
Valence electrons are involved in chemical
bonding.
Bonding and Valence Electrons Video Clip
Valence Electrons:
Valence Electrons can be easily found by
looking at the Group number or “A”
number located above the column where
the element is located on the periodic
table.
Examples:
13
3
14
4
3
Al= Group # ___ and ____A so it has ___ valence electrons.
4
Pb= Group # ___ and ____ A so it has ____ valence electrons.
Valence Electrons the Quick and Easy Way
Determine the number of valence electrons.
•Phosphorus
•Argon
•Lead (has exceptions)
•Barium
5 valence electrons
8 valence electrons
4 valence electrons
2 valence electrons
Exceptions
• * This ONLY works for Group A Elements
(the Representative Elements)
• Helium  two valence electrons
Label the Valence Electrons for each Column on the Periodic Table
Label the Valence Electrons for each Column on the Periodic Table
LEWIS DOT DIAGRAMS: is a diagram in
which the chemical symbol of an element
represents the nucleus and the inner energy
level and “dots” represent the valence
electrons.
There can only be up to 8 valence electrons and
thus only 8 dots around a symbol. The first 4 dots
are single and then they pair up as more are
added. Octet rule states that all atoms wish to
be like the Nobel gases (group 18) with a full
valence of 8 electrons.
Lewis Dot Diagrams
Element
Symbol
One Dot for
Each Valence
Electron
How Are the Dots Arranged?
1
8
4
5
X
7
3
2
6
Example Dot Diagrams
Draw the dot diagrams for each of the
following elements.
•Helium
He
•Carbon
C
F
•Neon
Ne
Oxidation numbers
OXIDATION NUMBERS: is the number of electrons an
atom gains, loses, or shares when it
forms a chemical bond and achieves the octet rule.
This will also be the charge of the ION.
Metals as a rule lose electrons and will have a (+) charge.
Nonmetals will gain electrons and have a ( -) charge
Nobel gases in group 18 will not
lose or gain and have a 0 charge
Label the periodic table for the ion charge created as atoms
achieve the Octet rule (full valence of 8):
4
0
0
4
-4
-1
7
8
0
0
Homework
page 7
Nomenclature
Ionic Bonding
Thursday - Day 3 Notes
Warm-up
Draw the Lewis Dot diagram for the following elements:
• Ne
•P
• Li
•N
• Cl
Video Clip on How
Atoms Bond: IONIC
COMPOUNDS
Click the link below to watch the video:
http://www.nbclearn.com/portal/site/learn/chemist
ry-now/how-atoms-bond
Quick Review
• _Ions_____ - atoms that have lost or gained
one or more electrons.
• __cation___ – positively charged ion
• _____anion___ – negatively charged ion
• The charge on the ion is known as the ___oxidation
number____
• __Polyatomic ion____ – ion consisting of two
or more atoms
Practice - write the ion with the charge for the following
elements
* Li
+
* Be 2+
3+
2+
* H+
+-4
* K
* Ca
* Si
+
* S 2-
* O 2-
* Na+
* Fr +
* N 3-
*F-
* Cl -
* P
* Al
3-
NOTES #3: Binary Ionic Chemical Names
and Formulas
• Ionic bonds are formed between a
metal and a nonmetal OR
cation + anion.
• The bond involves the transfer of electrons from the
metal to the nonmetal.
• The electron is transferred from the cation to the anion so that both
atoms have a complete valence shell (usually 8 electrons in valance).
• The overall charge of ionic compounds must equal
zero.
Naming
Ionic Compounds
* First
name the cation and then the anion.
(metal)
(nonmetal)
* Change the ending of the anion to –ide.
Example:
•MgCl2
magnesium chloride
•Li2S
Lithium sulfide
_________________________
Magnesium
oxide
MgO _________________________
K3P
Potassium
phosphide
________________________
CsCl
________________________
Ba3N2
Practice
Cesium chloride
Barium nitride
________________________
DRAWING Lewis Dot Structures for Ionic Compounds
•
•
The overall charge on the compound must equal zero, that is, the number of
electrons lost by one atom must equal the number of electrons gained by the
other atom.
The Lewis Structure (electron dot diagram) of each ion is used to construct the
Lewis Structure (electron dot diagram) for the ionic compound.
The Lewis Dot structures show the location of the valence
electrons after the electrons have been transferred.
Examples: Lithium fluoride
•
Lithium atom loses one electron to form the cation Li+
•
Fluorine atom gains one electron to form the anion F•
Lithium fluoride compound can be represented as
Remember the Octet rule….
DRAWING Lewis Dot Structures for Ionic Compounds
Draw the Lewis structure of Lithium oxide.
chemical formula for this compound?
What would be the
Writing Formulas for Binary Ionic Compounds
 When given two ions, __________________
Balance the charges and make them the
subscripts
___________________.
 Do NOT keep the +/- signs
 _______________
Reduce subscripts if possible
This means we must reduce the subscripts if they have a common
denominator.
Example: Ca4F8
CaF2
Writing Formulas for Binary Ionic Compounds
A. Using Balanced charges Method:
B. Using the Crisscross method:
**Sum of charges must equal zero.
Ex:
a. Na+1 + Cl-1  NaCl
 Example: Li+1 O-2
(+1 + -1 = 0)
b. Mg+2 + O-2  MgO * (+2 + -2 = 0)
* Don’t write this Mg2O2 because it must be
reduced.
Now, let’s use the name to write the chemical formula
Name

Lithium oxide
cation
anion
Li+1
O-2
_______ _______
Li+1
formula
Li2O
_____________
Lewis Dot Structure
Important Facts about Ionic Compounds
• We use subscripts to represent the
number of each ion.
Al2O3
2 Aluminum Ions and 3 Oxide Ions
For example 2…Change it from Magnesium sulfide to
Magnesium phosphide
A. Using Balanced charges Method:
Mg2+
Mg2+
Mg2+
6+
=0
6-
Name

Mg2+
P3P3-
and
Magnesium phosphide
B. Using the Crisscross method:
cation
2+
Mg
______
Mg 3
anion formula
Mg3P2
P3- ____________
_______
and
P3-
S2
Lewis Dot Structure
Homework: Page 10
• For added help: watch this video
• And use your periodic table!!!!
Notes 4: Binary Ionic Compounds with
Transition Metals (Multivalent cations)
• Multivalent Cations are found mostly in
the group B elements. (the middle of the
periodic table)
These elements are also known as the Transition
metals.
Roman
Charge
Numeral
If your cation is a transition metal,
then you must specify the charge
with a Roman numeral.
Example: Iron (III) Sulfide
Just like the compounds we looked at
yesterday, the sum of charges must
equal zero . and we can still use the
Criss-cross method when writing the
chemical formula.
I
II
III
IV
V
VI
VII
VIII
+1
+2
+3
+4
+5
+6
+7
+8
Writing & Naming Formulas with Roman
Numerals Practice
Cu+
S2-
Cu2S
Mn2+
O2 -
MnO
Sn4+
F-
SnF4
Lead II iodide
Pb2+
I-
Iron III oxide
Fe3+
O2-
Lead IV oxide
Pb4+
Cobalt III phosphide
Co3+
P3-
Naming Ionic Compounds with Roman Numerals
• If there is a transition metal (B group
element) present in the formula, you
will need to include a roman numeral
when you name the compound.
• So, which metals DO NOT require a
roman numeral?
• Al3+, Zn2+, Cd2+ and Ag+
Writing Multivalent Compounds
HOMEWORK
Complete page 12
REMEMBER:
How can you determine the charge or roman
numeral?
You will have to work backwards.
And
Roman Numeral = Charge of the Metal
Warm-up
Chemical Name
Chemical Formula
• Copper II chloride
_______________
• ______________________ PbO2
• Zinc sulfide
_________________
Notes #5: Polyatomic Ions
• A polyatomic ion are groups of
atoms that behave as one unit.
• They are treated like single ions in formulas, but use parenthesis
when more than one is used in a formula.
• NEVER change name or look of polyatomic. If you change the
subscripts for any part of the polyatomic, then it is no longer that
same polyatomic ion.
• Otherwise….use all the same rules for naming and writing
compounds as with any other Binary Ionic compound.
EX:
NH4+ is not the same as NH+
CO32- is not the same as CO22- or CO2-
Polyatomic Ion Practice
Formula
Al+3
CO3 -2
Al2(CO3)3
Ca+2
NO3 -1
Ca(NO3)2
K+1
ClO3 -1
KClO3
Name
Aluminum carbonate
Calcium nitrate
Potassium chlorate
Question: How would potassium chlorite be different?
K+1
ClO2 -1
KClO2
Name the following compounds
Ba(OH)2
Barium hydroxide
CaSO4
Calcium sulfate
(NH4)3P
Ammonium phosphide
Write the formula for the following compounds:
cation
Strontium phosphate
2+
Sr
________
anion
_________
formula
______________
Lithium acetate
________
_________
______________
Sodium sulfate
_________
_________
______________
Formula Writing for Compounds
Tips for Success
• Before writing any formula,
• Identify the type of compound.
• Ionic  Metal and a Nonmetal or PAI
• Molecular  Only Nonmetals
• For all ionic compounds, circle
polyatomic ions.
Examples
• iron(III) nitrate
I
• carbon tetrachloride M
• sodium oxide I
Fe(NO3)3
CCl4
Na2O
• barium hydroxide I
Ba(OH)2
• dinitrogen trioxide M N2O3
• ammonium carbonate
• cobalt(III) nitrite
I
(NH4)2CO3
I Co(NO2)3
Naming Ionic Compounds with Polyatomic Ions
• When you name a compound with a
polyatomic ion, the polyatomic ion keeps its
name.
• It is easy to identify a compound with a
polyatomic ion because it will have more
than 2 elements (more than 2 capital
letters).
Tips for Success
• Before naming ANY compound,
• Determine the type of compound.
• If the compound is molecular, remember
use prefixes.
• If the compound is ionic, answer the
following questions.
• Does the metal need a roman numeral?
• Does the compound have a polyatomic
ion?
Examples
• NaHCO3 I sodium hydrogen carbonate
• (NH4)2O
• FeSO4
I
I
ammonium oxide
iron(II)
sulfate
I
• AgC2H3OI2 silver acetate
• Ni(NO
M3)2
• ClO
I
nickel(II) nitrate
chlorine monoxide
• AuClO3 gold(I) chlorate
Homework:
• Page 14
Warm-up
• Which of the following compounds represent trichlorine
hexoxide?
• A. Cl3O6
• B. ClO3
• C. O3Cl6
• Which of the following compounds represent manganese (III)
oxide?
• A. MgO
• B. Mn2O3
• C. Mg2O3
Keys to Success
• Before naming ANY compound,
• Identify the type of compound.
• Molecular? Ionic? Acid?
• If it is molecular, remember to use your
prefixes.
• If it is ionic, ask yourself.
• Does the metal need a roman numeral?
• Does it contain a polyatomic ion?
• If it is an acid, which pattern does it follow?
Mixing It Up!
• H2CrO4
• Na2SO3 I
• HF
A
• P5O10
M
A
chromic acid
sodium sulfite
hydrofluoric acid
I pentaphosphorus decoxide
• Fe(C2H
I 3O2)2 iron(II) acetate
• ZnCl2 A
zinc chloride
• H3PO3
phosphorous acid
Keys to Success
• Before writing the formula for ANY
compound,
• Identify the type of compound.
• Molecular? Ionic? Acid?
• If it is ionic, does it contain a polyatomic ion?
• If it is an acid, which pattern does it follow?
• No Oxygen?
• -ATE Polyatomic Ion?
• -ITE Polyatomic Ion?
Examples
• barium phosphate I
• bromic acid A -ate
Ba3(PO4)2
• ammonium dichromateI
(NH4)2 Cr2O7
• iron(III) sulfide I
Fe2S3
HBrO3
• dichlorine heptachlorideM Cl2O7
• hydrosulfuric acid A No O H2S
• gold(III) chlorate I
Au(ClO3)3
Classwork due at the end of the period!
• Page 15
Warm-up: se puzzle pieces to make 2 ionic
compounds
•Let’s try the first one together.
•What is the compound formed between Mg and F?
Mg2+
Magnesium
Metal
Mg
Metal’s
Charge
+2
Ffluoride
Ffluoride
Nonmetal’s
Nonmetal
Charge
F
-1
A perfectly assembled
compound should be a
square or a rectangle.
Picture of
Puzzle
Pieces
Formula
Name
MgF2
magnesium
fluoride
Sum of
Charges
0
Notes #6: Naming & Forming Covalent (Molecular) Compounds
Covalent (Molecular) Compounds
• Covalent compounds are made up of all nonmetals (also called molecular compounds).
• To name a covalent compound, name the first element, then name the second one and
change its ending to ide. Use prefixes to show how many atoms of each element you
have.
• Molecular compounds contain covalent bonds and are formed when elements share
valence electrons.
Rules for naming and writing covalent molecules
are different than those for ionic compounds.
• NO crisscrossing
• NO reducing
• Prefixes are used in naming to show the number of each element
You MUST memorize
the prefixes!!
nonmetals except
Nobel gases (group 18)
*mono is omitted if on the first element!!
Examples:
**Remember mono is omitted if on the first element!!
• P2O5
diphosphorus pentoxide
• CCl4
carbon tetrachloride
• S2O3
disulfer trioxide
• NO2
nitrogen dioxide
• CO
carbon monoxide
To write the formula of a covalent compound, simply
translate the prefixes and element names.
•Dinitrogen dioxide
N2O2
•Diphosporus heptoxide
P2O7
•Tetrasulfer tetranitride
S4N4
Homework
•Page 17