Combining ElementsCombining Elements

D. Crowley, 2007D. Crowley, 2007

Combining ElementsCombining Elements

To know what happens when elements To know what happens when elements combine, and to be able to name combine, and to be able to name compoundscompounds

Element or not?Element or not?

Name of substanceName of substance FormulaFormula Single element?Single element? More than one More than one element?element?

OxygenOxygen OO22

Carbon monoxideCarbon monoxide COCO

HeliumHelium HeHe

WaterWater HH22OO

Sodium chlorideSodium chloride NaClNaCl

Carbon dioxideCarbon dioxide COCO22

YESYES

YESYES

YESYES

YESYES

XX

XX

XX

XX

XX

XX

YESYES

YESYES

New materialsNew materials

Remember, a compound is formed when two or more elements are chemically bound

This results in the compound having different properties than the original elements had

E.g. oxygen and hydrogen are a gases, yet combine this together in a chemical reaction and they will form water, a liquid at room temperature

E.g. sodium (a grey metal) and chlorine (a greenish-yellow gas) are both very dangerous. But burn sodium in chlorine, and you produce sodium chloride - (table salt)

Naming rulesNaming rules

To make your chemical name, you simply combine the names of the elements you reacted together to make your compounds

E.g.

carbon + oxygen

sodium + chlorine

iron + oxygen

copper + oxygen

carbon dioxide

sodium chloride

iron oxide (rust)

copper oxide

The ide is added to the end to tell us the elements have joined together, forming a compound

When you add oxygen and 2 other elements, the name usually ends in ate

SymbolsSymbols

A chemical formula is made up of the symbols for the elements it contains

E.g. carbon monoxide is CO

This tells us it contains carbon and oxygen - for every one carbon atom there is one oxygen atom

Many chemical formulas also contain numbers - these tell you what the ratio of elements in the compound is

E.g. carbon dioxide is CO2

This means that for every carbon atom there is, there are two oxygen atoms

PracticePractice

Ide

Using your sheet, see if you can predict what compound will be made. Be careful of the name

If you complete this, try and work out the symbol equation.

Ate

If you have completed this, try table 2

You have five minutes…

Element + Element Element + Element Compound Compound Element + Element Compound

Carbon(C)

+ Oxygen(O)

Carbon(C)

+ Oxygen(O2)

Hydrogen(H2)

+ Oxygen(O)

+ Hydrochloric Acid (HCl)

Magnesium(Mg)

+ Oxygen

+ Oxygen Iron Oxide(Fe2O3)

Carbon monoxide

(CO)

Carbon dioxide(CO2)

Water(H2O)

Magnesium Oxide(MgO)

Hydrogen(H)

Iron (II)(Fe)

Chlorine(Cl)

Element + Element + Oxygen Element + Element + Oxygen Compound Compound

Element + Element + Oxygen Compound

++ ++ Calcium Calcium carbonatcarbonat

e e (CaCO(CaCO3))

CopperCopper ++ CarbonCarbon ++ OxygenOxygen Copper

Carbonate

(CuCO3)

Calcium(Ca)

Carbon(C)

Oxygen(O)

Copper ParcelsCopper Parcels

Experiment: -

You are going to hammer squares of copper into a tight parcel that is as air tight as possible

You are then going to heat this over a Bunsen burner (using the tongs)

Once you have done this, let the copper cool down and tidy up your desk

Write down what you have found - explain the difference in colour

Represent this using a word and symbol equation

DifferencesDifferences

Hopefully you found that you copper parcel has shown a good colour change - one area which was heated has changed to a black, sooty colour, whilst the other remains the original copper colour. This is because some of the copper (the area which was heated) has reacted with the oxygen, forming the compound copper oxide which is a darker red colour (different properties to the original copper element)

*The black formation is carbon from the Bunsen

copper + oxygen copper oxide

2Cu + O2 2CuO