Theory:

We all have a name, and we named the materials and objects in our surroundings to identify them. Similarly, scientists have also named atoms and given unique symbols to identify them.
 
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Biometric Identification
 
Now let's take a look at those symbols of the elements.
Symbols of elements:
Jöns Jacob Berzelius, a Swedish chemist, proposed that element symbols be made up of one or two letters from the element's name.
 
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Jöns Jacob Berzelius
 
We can see that each element has a name and a unique chemical symbol. Some elements' symbols are made up of the first letter of the name and a letter that appears later in the name.
But, John Dalton was the first scientist to use the symbols for elements in a very specific sense. Below we see the symbols of the atoms proposed by John Dalton.
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We can see that each element has a name and a unique chemical symbol. Some elements' symbols are made up of the first letter of the name and a letter that appears later in the name.
Example:
(i) Hydrogen - H
 
(ii) Magnesium - Mg
But some elements named after another language like Greek and Latin, so those elements would be different from others.
Example:
i) The symbol of iron is \(Fe\) from its Latin name Ferrum \((Fe)\).
 
ii) Potassium symbol is \(K\) from Kalium \((K)\).
 
iii) Sodium symbol is \(Na\) from Natrium \((Na)\).
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Nowadays, elements names are authorised by the IUPAC (International Union of Pure and Applied Chemistry).