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WRITING IONIC AND MOLECULAR COMPOUNDS
Unit B - Chemistry
3.1 Naming Ions and Compunds
IonsAn ion is an atom or a group of atoms that has become electrically charged through the loss or gain of electrons.
Cation- positive chargeAnion- negative charge
Ions
Ions are elements with a charge- can be positive or negative charge
When a non-metal element has a charge its ending changes to become _________ide Example: Chloride Write out the differences between chlorine
and chloride using the atomic symbol
On the Periodic Table
What is the charge on the alkali metals?
What does that mean?What is the charge on the alkaline
earth metals?What does that mean?What is the charge on the halogens?What does that mean?What is the charge on the noble
gases?What does that mean?
Drawing Diagrams
Lithium Atom Lithium IonNoble Gas
Chlorine Atom Chloride IonNoble Gas
More Practice
Magnesium atom Magnesium IonNoble Gas
Oxygen Atom Oxide ionNoble Gas
I Can…
Read and interpret chemical formulasUse naming rules for elements,
compounds and chemical reactions: use both IUPAC and common names
IUPAC
International Union of Pure and Applied Chemistry
They are the body responsible for agreeing on the appropriate name for every chemical compound discovered
Chemical Formula
A chemical formula identifies which elements, and how much of each element are in the compound
What is a compound? The chemical combination of two or more
elements in a specific ratioFor example: CO2
Number of carbon atoms? Number of oxygen atoms? Number of total atoms?
Be careful with CAPITALS!
CO- carbon monoxide (1 carbon and 1 oxygen)
Co- cobalt, which is a transition metalNOTE: every time we see another
capital letter that tells us there is a new element
States of Matter
Another common notation added to a chemical compound indicates its state at room temperature.
We show states of matter using a subscriptCu(S) –Indicates a solidH2O(l) – indicates a liquid at room
temperatureCH4(g) -indicates a gas
Multivalent Atoms
Many of the Transition Metals are Multivalent metals (more than one charge):
Sn2+
Sn4+
Fe2+
Fe3+
Polyatomic Ions
Polyatomic Ions are ions that contain more than one ion:
Why are Polyatomic Atoms named with –ATE/-ITE endings? To differentiate the number of oxygen atoms. Example PO4 -3is phosphate, PO3
-3 is phosphite
NH4+
SO42-
MnO4-
Cr2O72-
To memorize
Water (H2O)Ammonia (NH3)Methane (CH4)Table Salt (NaCl)Sodium Hydroxide (NaOH)
3.2 Ionic Compounds
I Can…
Distinguish between ionic and molecular compounds, and describe properties of each
Read and interpret chemical formulasIdentify and describe formulas for common
household compoundsBuild or draw simple ionic and molecular
compoundsIdentify ratios of atoms in common
compounds and predict ratios of atoms in binary ionic compounds, using ionic charges
Represent familiar reactions, using word equations and chemical formulas
Introduction – Properties of Ionic Compounds
Ionic Compounds are all solid at room temperature
Many ionic compounds dissolve in water and becoming aqueous (liquid)
Ionic compounds in solutions conduct electricity
Structure
Ionic Compounds are made of a metal ion and a non-metal ion
When ions are combined they form a crystal Example: Table Salt
Structure in the Solution
Ionic compounds in solutions conduct electricity
When in a solution the ionic crystals will dissolve and the ions will float separately from one another
This allows conductivity: electrons (electricity) can move through the solution when there are ions.
Ionic Compound Conducting Electricity?
https://phet.colorado.edu/en/simulation/sugar-and-salt-solutions
Ion Charges
To indicate ions in written notation, a plus sign (+) or a minus sign (-) is placed to the upper right of the element symbol element
For example NaCl would be written as Na+ and Cl-
How do the numbers work in a chemical formula?
Let’s think about itHow many electrons does a barium
ion want to give away?How many electrons does a chloride
ion want?So how many chlorides do we need
for each barium?
Note: Ionic compounds want full electron shells- to do this they either have to give or take away electrons
IONIC COMPOUNDS ALWAYS FORM BETWEEN A METAL ION AND A NON-METAL IONS
Writing Formulas
Write a metal ion and its chargeWrite the non-metal ion and its charge on
the same lineAdd extra ions until the charges on each
side balanceWrite the formula with the number of each
ion in subscript beside each symbolNote: Ion charges are at the top, the
number of ions are at the bottom
TRY:
Calcium ion and oxide ion
Sodium ion and iodide ion
Lithium ion and sulphide ion
Aluminum ion and selenium ion
Naming
For ionic compounds the metal ion is always named first- it doesn’t change its name
The non-metal ions goes second and it always changes its name to ____ide.
Practice Naming
Na2S(s)
BaL2(aq)
Ga2S3(aq)
CaO
The Periodic Table and Ion Charges
Take a look at the periodic table and look at the ion charge
Do you see a pattern?
Multivalent Bonds
If it is a multivalent metal we show the charge by using roman numerals 1=(1) 2=(II) 3=(III) 4= (IV) 5= (V)
It is written after the metal ion
Name CompoundsGold (I) fluorideCopper (II) oxideIron (II) sulphide
Practicing Naming
FeOFeNCuF2
Co2O3
HgS
What about the Box of Compounds?
If you look at your periodic table, you have polyatomic ions. They are groups of elements that have properties like ions.
When writing these in a compound, you will write them out the same way you see them written.
NaHCO3 – sodium bicarbonate (baking soda)NH3OH – ammonium hydroxide
Practicing Naming
CaCO3
NH4NO3
Sn3(PO4)4
K2Cr2O7
To Do:
Naming Ionic Compounds WorksheetIonic Compound ID Assignment
3.3 Molecular Compounds
I Can…
Distinguish between ionic and molecular compounds, and describe properties of each
Read and interpret chemical formulasIdentify and describe formulas for common
household compoundsBuild or draw simple ionic and molecular
compoundsRepresent familiar reactions, using word
equations and chemical formulas
Introduction – Properties of Molecular Compunds
Molecular compounds are made from 2 or more non-metals
They can be solid, liquid, or a gas.Molecular compounds are made of
atomsThe atoms in a molecular compound
share their electronsEach atom fills its electrons by sharing
electrons
Molecular Compound Conducting Electricity?
Molecular compounds do not conduct electricity.Why?
https://phet.colorado.edu/en/simulation/sugar-and-salt-solutions
Writing Formulas
Since there are no ions we don’t need to balance charges
We use a prefix to tell how many molecules there are
1. mono2. di3. tri4. tetra5. Penta6. Hexa
7. Hepta8. Octa9. Nona10.Deca
Steps to Naming
Write down the name of the first element with its prefix
Write down the name of the second element using _____ide and its prefix
EXCEPTION- when the first element is 1 we do not use the mono prefix
Practice
CO2
N20Dinitrogen trioxideNF3
CCl4
Diselenium trioxide
Molecular or Ionic?
Molecular compounds have higher melting and boiling points that ionic compounds
Molecular compounds dissolved in water do not conduct electricity
Ionic compounds dissolved in water conduct electricity
Ionic Compound Conducting Electricity?
https://phet.colorado.edu/en/simulation/sugar-and-salt-solutions
Molecular or Ionic?
H2OCuCl2
NaClNH3
C12H22
BaSO4
Al2S3
To Do:
Naming Molecular Compounds Worksheet
