writing ionic and molecular compounds unit b - chemistry

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