118 Elements – Their Symbols and Atomic Number

The periodic table is an essential tool widely used by scientists, professionals, teachers, and students of chemistry to find information about chemical elements. It was first developed by Dimitri Mendeleev, who is known as the Father of the Periodic Table. Mendeleev’s table was based on the atomic mass of the elements known at his time. The modern periodic table, however, is based on Henry Moseley’s periodic law, which states that the properties of elements are periodic functions of their atomic numbers. The periodic table now includes 118 elements.

Key Characteristics of the Periodic Table

• Order of Arrangement: Elements are arranged in increasing atomic numbers.
• Symbol Representation: Elements are denoted by unique symbols, typically one or two letters. Symbols may also have three letters for newly synthesized elements.
• Groups and Periods: Elements are organized in vertical columns called ‘Groups’ and horizontal rows called ‘Periods’.
• Periodic Trends: Elements are grouped based on similar properties and trends, such as elements in group 1A being soft metals that react with water.

118 Elements – Their Symbols and Atomic Number

Symbols of Elements

A chemical element’s symbol is a shorthand notation, usually consisting of one or two letters derived from its English name. Some symbols are derived from Latin or Greek names, like ‘Au’ for gold (Aurum) and ‘Fe’ for iron (Ferrum).

Conventions for Symbols

• The first letter of a symbol is capitalized, and any subsequent letters are lowercase (e.g., ‘Ca’ for Calcium, ‘He’ for Helium).
• Single-letter symbols are always capitalized (e.g., ‘N’ for Nitrogen, ‘O’ for Oxygen).

Importance for Students

Understanding and memorizing the symbols and valency of the 118 elements is crucial for writing chemical formulas and equations efficiently.

Valency of an Element

Valency is the ability of an atom to gain or lose electrons to achieve a stable configuration, often similar to noble gases. The valency is determined by the number of electrons in the outermost shell (valence electrons).

Atomic Number

The atomic number is the total number of protons in the nucleus of an atom and is denoted by ‘Z’. It determines the chemical properties of an element.

Occurrence of Elements

Out of the 118 elements:

• 98 are found in nature (Hydrogen ‘H’ to Californium ‘Cf’).
• The rest are synthesized in laboratories (e.g., Einsteinium ‘Es’, Fermium ‘Fm’, and Nobelium ‘No’).

Nature of Occurrence

• Noble gases and some metals like gold, silver, and copper occur in their pure form.
• Most elements occur naturally but not in their native form; they are usually found as compounds.
  

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