Page 41 - Curriculum Visions Dynamic Book. To close the book, close the tab.

Shell, shell diagrams
The term or diagram used to describe the imaginary surfaces outside the nucleus of an atom that would be formed by a set
of electrons of similar energy.
The outermost shell is known as the valence shell. For example, neon has shells containing two and eight electrons.
 Shell, shell diagrams – This is a shell diagram for the element silicon. It contains 2 electrons in its inner shell, 8 in the middle shell, and 4 in the outer shell. The nucleus is in the centre.
This is only a convenient representation – real
elements do not
look like this.
Silicon (Si)
41
 Silicon – Glass is an amorphous form of silica, meaning that it has not formed any true crystals. That is why it is transparent.
 Silicon – Most silicon is found in the form of silicates – compounds of silicon and oxygen. This is the mineral agate, a silicate coloured orange by atoms of iron.
Silicon (Si)
Element 14 on the periodic table. A metalloid in group 4 (the carbon group). Silicon forms about 28% of the Earth’s crust, making it the second most common element in the crust after oxygen.
Silicon was discovered in 1824 by the Swedish chemist Jöns Jacob Berzelius. It does not occur uncombined, but always with
oxygen as silicates and other minerals. Quartz is a
compound of silicon and oxygen. Sand and clay are
also compounds dominated by silica.
Pure silicon is a hard, dark grey solid. It is unreactive with water or acids and so is used
widely to make containers. It is the main
component in glass. The atomic structure of
silicon has made it a very important semi-conductor. It
is the basis of ‘silicon chips’. (See also: Arsenic.)