Periodic table of elements with names and symbols

Periodic Table of Elements

The periodic table of elements Created by Dmitri Mendeleev in 1869 is a tabular arrangement of all known chemical elements, organized by atomic number, electron configuration, and recurring chemical properties.

The 109 elements known to man exhibit a variety of properties and form a large number of compounds. Hence, to study them independently would be difficult. As these elements resemble in physical and chemical properties we can group them together. For example, coinage metals like copper, gold and silver exhibit similar properties, these could be grouped together. Mandeleev produced a periodic table of elements based on the atomic weights of the elements. But as the physical basis underlying the periodic classification became their atomic number and not atomic weights, the periodic table was arranged according to the atomic numbers.

The Modem Periodic Table of elements (Table 219) is the long form of the periodic table proposed by Rang (1893), developed by Warner (1905) and extended by Bury (1921). The table is also known as Bohr table because it follows the Bohr’s scheme of arrangement of elements in four types based on their electronic configurations and modern periodic law.

1. 18 horizontal columns called group
2. 1 vertical rows called periods
3. 4 blocks named s, p. d and / blocks.

Man made elements in periodic table

For many years, it was believed that element 92 (uranium) had the heaviest atoms occurring naturally on Earth. It was believed that as atomic size increases, the atoms become Iess stable and any atoms of heavier elements that might once have been present in Earth had broken down. Since 1940 chemists in the United States and the Soviet Union have been making “transuranium” elements artificially. Glenn Seaborg (1912-), involved with much of this work, used the periodic table to predict the likely properties of transuranium elements. His predictions go as far as elements 168, although, for physical reasons, few of these elements would be stable for long enough to check whether or not their properties did coincide with predictions.

But another of his theories based on the periodic table of elements has been proved. Because of their chemical similarities, members of the same family of elements often occur in the same minerals. Seaborg predicted that, if there were any traces of transuranic elements left on Earth, they would be found in minerals rich in other elements of the same family. In 1971, he discovered naturally occurring plutonium in a sample of uranium ore.

Importance of the Periodic Table

The periodic table is often called the “map of chemistry” because it shows patterns in how elements behave.

Understanding Chemical Behavior.

1. Elements in the same group show similar reactions due to the same number of valence electrons.
2. Example: Chlorine (Cl), Bromine (Br), and Iodine (I) (Group 17 – Halogens) all form salts with metals (like NaCl, NaBr, NaI).

The discovery of new elements.

1. The periodic table helped scientists predict missing elements before they were discovered.
2. Example: Mendeleev left gaps in his table and predicted properties of “eka-silicon,” which was later discovered as Germanium (Ge).

Industrial and Practical Use

1. The periodic table helps industries choose elements based on their properties.
2. Example: Copper (Cu) is used in electrical wiring due to high conductivity, while Tungsten (W) is used in bulbs because it has a very high melting point.

Structure of the Periodic Table

Periods

• There are 7 periods in the periodic table of elements.
• Each period represents a new electron shell being filled.
• Example:

Period 2 → Elements from Lithium (Li, atomic no. 3) to Neon (Ne, atomic no. 10).
These all have 2 electron shells.

Groups.

• There are 18 groups in total.
• Elements in the same group have the same number of valence electrons, so they show similar chemical properties.
• Example:
  • Group 1 → Alkali metals (Li, Na, K…) → All are highly reactive, soft metals.
  • Group 17 → Halogens (F, Cl, Br…) → All are reactive nonmetals forming salts.

Blocks (s, p, d, f)

The table is divided into blocks based on the type of orbital being filled:

1. s-block → Groups 1 & 2 (Alkali and Alkaline earth metals).
   • Example: Hydrogen (H), Sodium (Na).
2. p-block → Groups 13–18 (Metals, Nonmetals, Metalloids, Noble gases).
   • Example: Carbon (C), Oxygen (O), Argon (Ar).
3. d-block → Transition metals (Groups 3–12).
   • Example: Iron (Fe), Copper (Cu).
4. f-block → Lanthanides & Actinides (placed separately at the bottom).
   • Example: Uranium (U), Cerium (Ce).

Special Position of Hydrogen

• Hydrogen is unique.
• Sometimes placed in Group 1 (like Alkali metals) because it has 1 electron.
• Sometimes compared to Group 17 (Halogens) because it can form H⁻ ions.