Revision notes on elements, the periodic table and compounds.

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                                ELEMENTS

Definition:

An element is the basic building block of matter that cannot be broken down further by chemical reaction (This definition was suggested by Robert Boyle).

Element can be broken down ONLY by nuclear fission.

So far 106 elements have been discovered.

Water (H2O) is not an element – because it can be further broken down into 1 oxygen & 2 hydrogen atoms.

Carbon dioxide (CO2) is not an element – because it can be further broken down into 1 carbon & 2 oxygen atoms.

Atmospheric oxygen (O2) is not an element – because it can be further broken down into 2 oxygen atoms.

Note:

H2O………. CO2……. NO2   – these are compounds

Every element has:

  • A name (may vary in different language)
  • Name may be taken from their Latin name
  • Name may be taken after the scientist who invented them
  • Name may be taken after the place where they were found
  • A symbol (same all over the world)

In Universe:

Most abundant element in universe – H (hydrogen) & He (helium)

Stars are made of H & He

Earth’s crust:

Most abundant element in earth’s crust – O (oxygen = 45%) & Si (silicon= 25%)

Others:

  • Aluminium (Al) = 7%
  • Iron (Fe) = 5%
  • Sodium (Na) = 5%
  • Calcium (Ca) = 4%
  • Magnesium (Mg) = 3%
  • Nickel (Ni) = 3%
  • Potassium (K) =2%
  • Many others

Elements have their own properties:           

  1. Physical properties:
  • Colour
  • Density
  • Melting point
  • Boiling point

  1. Chemical property
  • The way they react in chemical reactions
  • Elements can combine with its own kind (O2) or with another kind of element (CO2)
  • But every element cannot react with every thing (only certain reactions can occur)
  • Some elements are non-reactive


CLASSIFICATION OF ELEMENTS:

  • Based on the formation:
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  • Based on physical properties

 Eg: Metal & Non-metal

  • Based on chemical properties

PERIODIC TABLE

This is the chart of all the known elements.

The chart is divided into:

  • 7 periods (horizontal rows)
  • 8 groups (vertical columns) – represented by Roman letters (eg: III, VI, V….etc)

Elements are grouped according to their atomic numbers in this chart

  • Elements of the same group have similar properties
  • Elements at the ...

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Punctuation, grammar and spelling are all to a high standard. Layout is great with a good sized easy to read text and clear subheadings.

The information contained in the revision notes are very basic but explain each topic very well. These would be very good notes indeed for anyone wanting to learn basic chemistry. The candidate covers a whole range of topics which encompasses good techniques and conveys this concisely and clearly.

The revision note content is to a very high standard. The candidate responds to the basic chemical concepts clearly and these would be a good aid for anyone just learning chemistry.