Slides in this set

Slide 1

Preview of page 1

Chemicals in the atmosphere
Some are elements whereas (oxygen, nitrogen)
some are compounds ( carbon dioxide)
Water vapour varies so proportions are given as
dry air
They are mainly molecular substances
Strong covalent bonds hold the atoms together
whereas weak forces hold the molecules
Weak forces results in low melting and boiling
points therefore they are mainly gases and liquids
There are no free elections or ions meaning there is no charge
because of this molecular substance don't conduct electricity.
Low molecular mass = low M.P and low B.P…read more

Slide 2

Preview of page 2

Covalent bonding
Covalent bonding is the sharing of electrons
Atoms which outer shell are not already full share a pair of
electrons to fill the outer shell
The bond is strong and needs a lot of energy to break it (high
activation energy) it is made due to electrostatic attraction
between the positive nuclei and the negative electrons between
Carbon need 4 electrons
Oxygen needs 2
So two double covalent bonds
Often shown by ball and stick models…read more

Slide 3

Preview of page 3

The hydrosphere
Made up of the water on the earth from oceans to puddles as well
as the compounds dissolved in the water
Many are ionic compounds such as salt e.g sodium chloride in sea
Pure water doesn't conduct electricity it is the ions dissolved in it,
dissolving the ion frees the ions electrons to carry and electric
current same when it is melted.
Ionic compounds are formed from charged particles, ions, opposite
charges attract to form a lattice giving the
Crystals they form there cubic shape.
Ionic bonds are strong taking lots of energy
to break them giving them high melting and
boiling points…read more

Slide 4

Preview of page 4

The lithosphere
Made from the crust and part of the mantle below, made up of
minerals often containing silicon, oxygen and aluminium. Silicon and
oxygen are mainly in the form of silicon dioxide.
Different rocks contain different minerals
Silicon dioxide forms a giant covalent structure with no charged ions.
As all the atoms are strongly bonded the substance is hard and
insoluble with high melting and boiling points
Silicon dioxide makes up ­ quartz, sandstone and granite
Some minerals are really rare and therefore valuable,
gemstones are an example of this ruby's, diamonds
ect. are all minerals with giant covalent structures.
The structure makes them strong and when polished
shiny, attractive for jewellery.…read more

Slide 5

Preview of page 5

The Biosphere
All living things are formed from compounds of the same basic elements-
Carbon, hydrogen, oxygen, nitrogen as well as phosphorus and sulphur.
These make up the vital molecules of life
-carbohydrates, fats ­ carbon hydrogen and oxygen (fat has more
-Proteins ­ always nitrogen sometimes sulphur
-DNA ­ phosphorus and nitrogen
They are all molecular no ions
The changes between spheres is shown in
· flow charts
· carbon cycle
· nitrogen cycle
· oxygen cycle…read more

Slide 6

Preview of page 6

Metals from Minerals
Metal ores are rocks made of minerals from which metals can be
extracted, the ore is often the oxide of the metal. Large amounts of
ore need to be mined to obtain small percentages of metal this can
be calculated
Step 1 calculate the proportion of the metal =
Step 2 find overall mass
The more reactive the metals are harder to extract
Some can be extracted by reduction with carbon or carbon
monoxide, oxygen is removed and given of as CO2
Metals higher in the reactivity series than carbon have to be
extracted using electrolysis. But only metals less reactive than
carbon can be reduced.…read more

Slide 7

Preview of page 7
Preview of page 7

Slide 8

Preview of page 8
Preview of page 8

Slide 9

Preview of page 9
Preview of page 9


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »