Identify the elements present in each of the following compounds and the number of each

element atom present.

Common salt: NaCl

Nitric acid: HNO3

Carbon dioxide: CO2

Sodium Hydroxide: NaOH

Sodium carbonate: Na2CO3

Copper sulfate: CuSO4

Sodium bicarbonate: NaHCO3

Ammonium sulfate: (NH4)2SO4

Potassium permanganate: KMnO4

Sodium thiosulfate: Na2S2O3

Calcium bicarbonate: Ca(HCO3)2

Calcium Nitrate: Ca(NO3)2

Ionic compounds

Properties of Ionic Compounds

• They have high melting and boiling points

• They are hard and brittle

• They do not conduct electricity in the solid state

• Will conduct electricity when in solution (dissolved in water) or molten (liquid state)

• Will often dissolve in water to form ions

Ions – Charged atoms or molecules

• An ion is an atom or molecule which has lost or gained one or more electrons, making it positively or negatively charged.

• Anions are negatively charged ions because they have more electrons in its electron shells than it has protons in its nuclei. They gain electrons e.g. Cl atom Cl-

• Cations are positively charged ions because they have more protons than electrons. Cations lose electrons e.g. sodium Na+

• The number of electrons an atom gains or loses is called its valency

• Cations and anions only form when cations transfer their outershell electrons to the anions

11 protons

11 electrons

11 protons

10 electrons 17 protons

18 electrons

17 protons

17 electrons

Getting stable – Bonding• The noble gases have a full outer shell and are

very unreactive or stable• Atoms are most stable when their outer shell is

full like the noble gases• How do you get a full outer shell? gain or lose or

share electrons when forming compounds and molecules

• A covalent bond is formed when electrons are shared between atoms.

• An ionic bond is formed when electrons are transferred from one atom to the other

Ionic Bonding

• Where does the Chlorine ion get that extra electron from?

• From Sodium who wants to give one away!• In ionic bonding, electrons are completely

transferred from one atom to another. • It happens between a metal and a non metal

Why?• Because metals form positive ions (cations)

and non metals form negative ions (anions)• The oppositely charged ions are attracted to

each other by electrostatic forces

• During a reaction of sodium with chlorine, sodium loses its one valence electron to chlorine.

• Resulting in a positively charged sodium ion and negatively charged chlorine ion.

Some important things to know

• Where do you find the charges for ions? Look at your valency table?

• Subscript is set below a word HelloYr 11

• Superscript is set above the Hello Yr 11

Rules for writing chemical formulas

1. Write the symbols and charge for ions involved. Write charge as superscript.

2. Determine the subscripts that will produce no charge

3. Check that the total positive charge and negative charge equal 0

4. Write final chemical formula without the charges just subscripts

Mg2+ Cl-

Mg2+ 2Cl-

2+ 2- = 0

MgCl2

Polyatomic Ions• For polyatomic ions you

cannot change the formula of the ion.

• For polyatomic ions if there is more than one of them you must put them in brackets and place the subscript outside

Na+ SO42- Al3+ SO4

2-

2 Na+ SO42- 2 Al3+ 3SO4

2-

2+ 2- =0 6+ 6- = 0

Na2 SO4 Al2(SO4)3

Fill in the table

Iodide I- Oxide O2-

Copper Cu2+

Potassium K+

Aluminium Al3+

Form an ionic bond between the following

• Na and Cl• Cl and F• Na and Mg• Mg and Br• NH4

+ OH-

• NH4+ SO4

2-

Naming Ionic Compounds

1. Name the positive ion first by writing full name of metal

• For metals that can have more than one charge (valency) the name of the metal is followed by the valency in capital Roman numerals in brackets e.g. Iron(II) Chloride

2. Name the anion second.

Negatively charged elements have the suffix or ending -ideExamples are oxide (O2-), sulfide (S2-), fluoride (F-), chloride (Cl-), bromide (Br-), iodide (I-), nitride (N3-), hydride (H-)

Naming Ionic Compounds3. Polyatomic ions which include oxygen in the anion

have the suffixes -ate or -ite. "ate" means there is more oxygen in the anion than

one ending in "ite"

Examples: sulfate (SO42-) has more oxygen than

sulfite (SO32-), nitrate (NO3

-) has more oxygen in the anion than nitrite (NO2

-)

Other examples are carbonate (CO32-), phosphate

(PO43-) and permanganate (MnO4

-)Exception: OH- is named hydroxide

Fill in the names of the following compoundsIodide I- Oxide O2-

Copper Cu2+ Copper (II) Iodide

Potassium K+

Aluminium Al3+

The ionic bonding model• Positive metal ions (cations) and negative non

metal ions (anions) are arranged in a regular arrangement, called a lattice

• The 3D lattice is held together strongly by electrostatic forces

Electrostatic forces are the forces between particles that are caused by their electric charges

Explaining properties of ionic compounds

Why do ionic compounds have relatively high melting points?

• Remember the melting point of a compound is when it goes from being a solid to a liquid

• The bond between the cations and anions are very strong and hence a large amount of energy is required to separate the bonds.

Why are ionic compounds brittle?• When an external force distorts the crystal

this causes ions of like charge (e.g. ++) to come close together (align) and the repulsion between these ions shatters the crystal.

Why are ionic compounds hard?The bonds between the cations and anions

are very strong.

Why do ionic compounds conduct electricity when in solution or molten? When molten (liquid) ions are able to slide past

each other. While in solution (meaning in water) ions dissociate (move out) from the lattice and can move freely so are able to conduct electricity

Why do ionic compounds not conduct electricity when solid?

When solid, the ions are not

able to move.

Why do ionic compounds dissolve in water?

• Water molecules are able to move between ions and free them by disrupting the rigid crystal structure

Uses of Ionic compounds• Read the pages 103 – 104 and summarizeYr 11 Camp Homework Due Date: Wednesday

Week 3

• Complete Ionic compound sheets.

• Add words to the glossary at the back of your workbook (look at pg 51, 70, 90 and 107 of your Chemistry textbook at key terms).

• Read Chapter 7: Covalent molecules, networks and layers (pages 110 – 131).