The Periodic Table

Revision notes for Chemistry. Easy to read and a quick notes to help you in your exams.

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  • Created on: 20-04-12 07:31
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The Periodic Table (C3)
Ionic bonding: Atoms turn into ions (become charged by losing or gaining
electrons) and then the positive ions attract the negative ions.
Covalent bonding: Two atoms share a pair of electrons.
Structure of an atom
All substances are made up of atoms. All atoms have a central nucleus. The
nucleus is positively charged because it is made up of protons which are
positively charged and neutrons which are neutral. The nucleus is surrounded
by negatively charged electrons arranged in shells. Overall, an atom has no
charge. An atom has no charge because it has the same number of protons and
electrons, so they cancel out each other's charge.
Mass number & Atomic number
All atoms of a particular element have the same number of protons. However,
some elements have varieties that have different numbers of neutrons; these
are called isotopes. They are easy to spot because they have the same atomic
number but a different mass number. For example, chlorine has two isotopes:
Mass number= 35 Mass number= 37
Atomic number= 17 Atomic number=17
35 37
Cl17 Cl17
The atomic number gives the number of protons, which is equal to the
number of electrons because atoms have no overall charge.
The mass number of the total number of protons and neutrons in the
Ions, Atoms & Molecules

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An uncharged particle is either...
An atom on its own e.g: Na, Cl.
A molecule of two or more atoms bonded together e.g: Cl2, CO2.
An ion is a charged atom or group of atoms e.g: Na+, Cl-.
Forming Ions
A positive ion is formed when an atom or group of atoms loses one or more
A negative ion is formed when an atom or group of atoms gains one or more
Ionic Bonding
A metal and non-metal combine by transferring electrons.…read more

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When a metal and a non-metal combine, electrons are transferred from one
atom to the other to form ions, each of which has a complete outer shell
Example 1:
The sodium atom has 1 electron in its outer shell which is transferred to the
chlorine atom to give them both 8 electrons in their outer shell. The atoms
become (Na+ and Cl-) and the compound formed is sodium chloride, NaCl.
The Periodic Table
Elements are the building blocks of all materials.…read more

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A vertical column of elements in the periodic table is called a group. Elements
in the same group have similar chemical properties. This is because they have
the same number of electrons in their outer shell. This number also coincides
with the group number e.g:
Group 1 elements have 1 electron in their outer shell.
Group 7 elements have 7 electrons in their outer shell.
Group 8 elements gave 8 electrons in their outer shell.…read more

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Methane, CH4- the carbon atom shares a pair of electrons with each hydrogen
Properties of Simple Covalently Bonded Molecules
The bond between two atoms in a simple covalently bonded molecule is very
strong. The intermolecular forces of attraction between molecules are weak.
This results in them having low melting points. They do not conduct electricity
as they do not have any free electrons.…read more

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Caesium has the lowest melting and boiling points. Generally, the density
increases as we go down the group (except for potassium). Caesium has the
greatest density.
Flame Test
Lithium, sodium and potassium compounds can be recognised by the colours
they produce in a flame test. Lithium- red, Sodium- yellow, Potassium-lilac.
Reacting Alkali Metals with Water
Alkali metals react with water to produce hydrogen and a hydroxide. Alkali
metal hydroxides are soluble and form alkaline solutions.…read more

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Chlorine, the most commonly used halogen, is used to sterilise water and to
make pesticides and plastics. It is extracted from sodium chloride by
As well as being used to produce chlorine, sodium chloride can also be used as...
A flavouring
A preservative.
Fluorine is the first element in Group 7, and is the most reactive element I the
group. It will displace all of the other halogens from an aqueous solution of the
metal halides.
Astatine is the fifth element in Group 7.…read more

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Some compounds conduct electricity when they are molten or in solution, but
not otherwise. In these cases, the liquid or solution must contain ions. A liquid
or solution that conducts electricity is called an electrolyte. An electrolyte can
be separated into its constituent parts by electrolysis.
When a direct current is passed through an electrolyte, the compound will
decompose and elements will be produced.…read more

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This reduces the energy needed for the
The Transition Metals
In the centre of the periodic table, between Groups 2 and 3, is a block of
metallic elements called the transition metals. This block includes iron, copper,
platinum, mercury and zinc.
Compounds of transition metals are often coloured...
Copper compounds are blue.
Iron (II) compounds are grey-green.
Iron (III) compounds are orange-brown.
Many transition metals and their compounds can be used as catalysts in
chemical process.…read more

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As the metal atoms pack together they build a structure of
Metals are able to conduct electricity because the atoms are very close
together and the electrons can move from atom to atom. At low
temperatures, some metals can become superconductors. A superconductor
has a very little or no, resistance to the flow of electricity. Very low resistance
is useful when you require...
A powerful electromagnet
Very fast electronic circuits
Power transmission that does not lose energy.…read more


lisa linsdell

Good revision notes on the periodic table. Also contains information on isotopes and ions.

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