Theory:

1. For the most common elements like non-metals, we use the first letter of the English name.
 
Element
Symbol
Element
Symbol
Boron
\(B\)
Oxygen
\(O\)
Carbon
\(C\)
Phosphorus
\(P\)
Fluorine
\(F\)
Sulphur
\(S\)
Hydrogen
\(H\)
Vanadium
\(V\)
Iodine
\(I\)
Uranium
\(U\)
Nitrogen
\(N\)
Yttrium
\(Y\)
 
2. If the name of an element has the same letter as another, use the first and second letter of English name. First letter in upper case and the second letter in lower case.
 
Element
Symbol
Element
Symbol
Aluminium
\(Al\)
Gallium
\(Ga\)
Barium
\(B\)
Helium
\(He\)
Beryllium
\(Be\)
Lithium
\(Li\)
Bismuth
\(Bi\)
Neon
\(Ne\)
Bromine
\(Br\)
Silicon
\(Si\)
Cobalt
\(Co\)
Argon
\(Ar\)

3. If the first letter or first two letters of an element is the same as another, use the first and second or third letter of English name that they do not have in common.
 
Element
Symbol
Element
Symbol
Argon
\(Ar\)
Calcium
\(Ca\)
Arsenic
\(As\)
Cadmium
\(Cd\)
Chlorine
\(Cl\)
Magnesium
\(Mg\)
Chromium
\(Cr\)
Manganese
\(Mn\)
Bromine
\(Br\)
Silicon
\(Si\)
Cobalt
\(Co\)
  
 
4. Some elements use old or Latin name of the elements. There are eleven such elements.
 
Element's name
Latin name
Symbol
Sodium
Natrium
\(Na\)
Potassium
Kalium
\(P\)
Iron
Ferrum
\(Fe\)
Copper
Cupuram
\(Co\)
Silver
Argentum
\(Ag\)
Gold
Aurum
\(Au\)
Mercury
Hydrargyrum
\(Hg\)
Lead
Plumbum
\(Pb\)
Tin
Stannum
\(Sn\)
Antimony
Stibium
\(Sb\)
Tungsten
Wolfram
\(W\)
 
5. Some of the elements are named using the name of country, or scientist, or colour, or mythological character, or planet.
 
Name
Symbol
Name derived from
Americium
\(Am\)
America (country)
Europium
\(Eu\)
Europe (country)
Nobelium
\(No\)
Alfred Nobel (Scientist)
Iodine
\(I\)
Violent (colour, Greek)
Mercury
\(Hg\)
God Mercury (mythologic character)
Plutonium
\(Pu\)
Pluto (planet)
Neptunium
\(Np\)
Neptune (planet)
Uranium
\(U\)
Uranus (planet)
 
Writing the symbols:
  
1. If an element has a single English letter as a symbol, it should be written in upper case.
 
Example:
  
\(H\) - Hydrogen
\(B\) - Boron

2. If an element has a two-letter symbol, the first letter should be written in the upper case and the second letter in lower case.

Example:
 
\(Ca\) - Calcium
\(Ni\) - Nickel
 
The symbol of an element signifies,
  • Name of the element.
  • One atom of the element.
Example:
 
The symbol "\(O\)" refers the element of oxygen, i.e., one atom of oxygen.
Reference:
file:///C:/Users/user/Desktop/Books/8th_Science/TN/8th_Std_Term_I_Science_EM.pdf