2. What is
Chemistry?
Chemistry is a branch of physical science, it
is the study of the composition, properties
and behaviour of matter. Chemistry is about
atoms and their interactions with other
atoms, and particularly with the properties
of chemical bonds. Chemistry is also about
the interactions between atoms (or groups
of atoms) and various forms of energy.
3. The Periodic
Table
A periodic table is a rectangular display of the
elements, organized on the basis of their:
Atomic numbers
Electron configurations
Recurring chemical properties
Elements are presented in order of increasing
atomic number.
5. What is
pH?
Two of the most important groups of chemicals are
the ‘acids’ and the ‘bases’.
Acids are solutions containing hydrogen (H+) ions.
Bases are solutions that contain metal oxide ions.
Alkalies are solutions that contain hydoxide ions
and carbonate ions.
An ion is an atom that has either gained or lost one
or more electrons.
The strength of acids and bases is measured using
a scale called pH. This stands for ‘postive
hydrogen ion concentration’.
It is a scale of around 0 to 14. Strong acids have a
low pH and strong alkalies have a high pH.
Pure water has a pH of 7, this is neutral.
In this diagram, it shows a base
The Acid in our stomachs is about 2, and so strong (blue-pH 10) being added to an
that it is able to ‘burn away’ rocks like limestone acid (yellow-pH 5/6), and
and chalk. neutralising it (becoming green-
pH 7)
6. There are 6 elements
that make up 99% of
your body
Oxygen 65% mass
Calcium 1.5% mass
25.6% atoms
0.25% atoms
Carbon 18% mass Hydrogen 10% mass
9.5 % atoms 63% atoms
Phosphorous 1.0% mass Nitrogen 3% mass
0.20% atoms 1.35% atoms
7. Cooking is a
Chemical Reaction
A chemical reaction
happens when bonds
between atoms and
molecules are made or
broken. We often melt or
freeze food in cooking, but
this is a reversible reaction.
It would be difficult to unmix
dough or cake mix, but no
chemical change occurs
until the heat from an oven
touches the dough or food.
8. Scientists can
turn Lead into
Gold
Scientist have been
able to turn lead into
gold. The nucleus of
lead has 82 protons
while the nucleus of
gold has 72 protons.
They turn lead into
gold by taking off 3
protons.They used a
nuclear reactor.
9. A Cubic metre of sea water
contains over 12 kilograms
of Metal.
Sea water contains minute The oceans contain
amounts of most metals. about 0.000,004 g
When rain water first falls to of gold per cubic
the ground it doesn’t contain metre. This may not
any salts. However, as this sound like a lot, but
water seeps through the when we think about
ground, it dissolves rocks how large the
like limestone and chalk. As oceans are, that is
a result, rainwater will about 5.5 million
contain dissolved mineral tonnes of gold.
salts when it flows into the
sea or it reaches our home
tap water.
10. A Rubber Molecule Can
Stretch to over Four
Times its Natural Lenght
Rubber is a biological molecule
made naturally by rubber trees.
A single rubber molecule is a long,
thin chain composed of hundreds
of thousands of atoms. The
molecules in a rubber band are
loosely tangled a round each other
in other in loops and coils. When
you pull on a rubber band, the
molecules straighten out so that the
band can become longer. Once the
molecules are straight the rubber
becomes very stiff.
