Types of Chemical Change

http://mrged.flexinet.com.au

You already know about,1.The two main types of chemical bonding

2. Writing chemical formulas

(formulae)

This week we will find out about;1.Synthesis Reactions

2. Decomposition reactions

3. Single replacement reactions

4. Double replacement reactions

The Periodic Table

Types of chemical bonding. Revision

Ionic BondingThis type of bondingwill occur when a metal reacts with a non -metal

It always involves a complete transfer of electrons

It always produces IONS (charged particles)

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1 Na reacts with 1 Cl Formula = NaCl

Covalent BondingThis type of bondingwill occur when a non- metal reacts with a non -metal

Here both atoms will share electrons

It always produces molecules (particles with no charge)

In this section we will find out how to write chemical FORMULAE

Rules leading to correct formulaP

lease copy into your exercise books

1. Positive ions (cations) can join to negative ions (anions)

2. Positive ions usually form the first part of the name (99% cases)

3. If the formula is correct there is no overall charge

4. If you have more than one polyatomic ion it is placed inside brackets

Essential training ions

Positive ions(Cations)

Negative ions(Anions)

+ 1 - 1

+2 - 2

+3 - 3

sodium Napotassium K

hydrogen H

lithium Lisilver Ag

fluoride F chloride Clbromide Br hydroxide OH

nitrate NO3

hydrogencarbonate HCO3

magnesium Mgcalcium Ca

barium Bazinc Zniron(11) Fe

copper Cu

carbonate CO3oxide Osulphide S

sulphate SO4sulphite SO3

chromate CrO4

aluminium Al

chromium Cr

iron(111) Fe

nitride Nphosphate PO4

ammonium NH4

Chemical Formulae 1.

CHARGESIONS NUMBERS

FORMULA

sodium fluoride

NaF

Chemical Formulae 2.

CHARGESIONS NUMBERS

FORMULA

magnesium fluoride

Mg

F

Chemical Formulae 3.

CHARGESIONS NUMBERS

FORMULA

silver hydroxide

Ag

OH

Chemical Formulae 4.

CHARGESIONS NUMBERS

FORMULA

calcium nitrate

Ca

NO3

Chemical Formulae 5.

CHARGESIONS NUMBERS

FORMULA

ammonium carbonate

NH4

CO3

Chemical Formulae 6.

CHARGESIONS NUMBERS

FORMULA

aluminium bromide

Al

Br

Chemical Formulae 7.

CHARGESIONS NUMBERS

FORMULA

chromium sulphide

Cr

S

Chemical Formulae 8.

CHARGESIONS NUMBERS

FORMULA

BLANK ITEM

Try these:

1. lithium sulphite2. barium hydroxide3. copper carbonate4. hydrogen sulphide5. magnesium nitride6. ammonium bromide7. aluminium oxide.

In chemistry there are millions of chemical reactions. But most reactions can be classified as one of four types of reactions:

Synthesis: A + B -> ABDecomposition: AB -> A + B

Single Replacement: A + BC -> AC + BDouble Replacement: AB + CD -> AD + CB

Synthesis (Composition)

In a synthesis reaction (also known as a composition reaction), two substances combine to form a larger substance.

C O O+ CO O

Here are 3 synthesis reactions:

Hydrogen + oxygen yields water

2H2 + O2 -> 2H2O

Magnesium + nitrogen yields magnesium nitride

3Mg + N2 -> Mg3N2

Iron + sulphur yields iron(II) sulphide

Fe + S -> FeS

DecompositionIn a decomposition reaction, a larger substance

breaks apart and forms two or more simpler substances.

The first thing you may notice about a decomposition reaction is that it is the complete opposite of a synthesis reaction. In fact many synthesis reactions can be reversed into a decomposition reaction.

When you burn hydrogen gas, the hydrogen combines with oxygen to produce water.

2H2 + O2 -> 2H2O With an electrical current, water can be decomposed into hydrogen and oxygen gas.

2H2O -> 2H2 + O2

Some examples of decompositionHeat copper carbonate and it will decompose(Refer to flash animation .swf)

CuCO3 -> CuO + CO2

(Most carbonates decompose producing the oxide and carbon dioxide)

Heat lead(11) hydroxide and it will decompose

Pb(OH)2 -> PbO + H2O

FORMALUMBRO.MOV

THERMITE.MOV

REDUCTIONCUO.MOV

FormWater.MOV

NitrogTriiodide.MOV

PrecipitaReact.MOV

6x Quicktime mov files

1. Watch all 12 mov files (available on SET drive)

2. Classify each as either, synthesis, decompostion, single of double replacement reactions

3. Write a correct chemical equation for each!Some may require some research

TRY THESE:

Single Replacement

In a single replacement reaction, a more active element replaces a less active element in a compound.

more reactive less reactive

Single Replacement

Here Mg is more reactive than Pb

Single Replacement

No surprise! fluorine is more reactive than chlorine

If fluorine gas is bubbled through a solution of potassium chloride, the fluorine will replace the chlorine.

2KCl + F --> 2KF + Cl

This reaction can be represented as follows;

Please note this PPT may be updated over the weekend

Mr G