Periodic Table

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Periodic Table PDF

What is Periodic Table ?

Periodic table is arrangement of chemical elements in the form of table. According to order of their atomic number, electronic configuration or chemical properties.

IUPAC Periodic Table of Elements

Why we need Periodic Table ?

Their was more than 115 elements have been discovered, which need to be arranged systematically.

How scientists arranged elements in Periodic Table ?

Scientists work hard to arrange elements in periodic table, today's periodic table is the result of different historical arrangements... 

History of classification of elements

     1.     Prout’s Hypothesis – 1815

     2.     Dobereiner’s Triads – 1829

     3.     Newland’s Law of Octaves – 1863

     4.     Lother Meyer Curves – 1869

     5.     Mendeleev’s Periodic Table – 1869

     6.     Modern Periodic Laws of Moseley -1913 

     7.     Modern Periodic Table ( of 18 columns ) 
  

Prout’s Hypothesis

                              According to this hypothesis atomic mass of elements is multiple of mass of hydrogenatom. So elements are related to each other on the basis of their atomic masses. It fails due to the reason that some elements do not have atomic mass in whole no. (Like chlorine have atomic mass of 35.5).

Dobereiner’s Triads

                                According to Dobereiner’s triads elements arranged in the group of three elements so that atomic mass of central element is appropriate mean of 1^st and 3^rd element. These groups of three elements are known as Dobereiner’s triads.

Example-

Element                                                           
 Li                Na                  K

Atomic Mass                                              
7                 23                  39

Mean of Atomic Masses of 1^st and 3^rd elements  is (7+39)/2  =   46/2   =  23

Newland’s Law of Octaves

According to Newland’s Law of Octaves elements arranged in the group of 8 elements and every 8^th element is similar to the 1^st element.

Li         Be         B        C          N         O           F

Na        Mg       Al        Si         P          S          Cl 

Lother Meyer Curves

                                       In 1869, Lother Meyer derived following conclusion by obtaining information from graph between the atomic weight at x-axis and atomic volume at y-axis.

      1.     Elements which have similar properties found on the same position on the graph curves.

      2.     All alkali metals like Li, Na, K, Rb, Cs, and Fr found at highest peak of curve.

      3.     Halogens like F, Cl, Br and I are found on ascending portion of curve.

      4.     Alkaline earth metals like Mg, Ca, Sr, Ba and Ra are found on descending portion of curve.

      5.     Elements which do not melt easily like Be, B, C, Al, Si, Cu etc. are found at lowest point of curve.

On the basis of above conclusions Lother Meyer give periodic Law:

                                                                                                  According to Lother Meyer periodic law – “Atomic volume of elements are periodic function of their atomic weights”.

Periodic Table

                        To classify elements a chart is prepared in which elements are arranged in rows and columns. These elements are arranged in table in such a way that the elements with similar properties are repeat after some intervals; also elements with similar properties are put in same column below one another. In periodic table vertical columns are called group while horizontal rows are called periods. In periodic table this repetition of properties in regular interval is known as periodicity. Read below chemistry notes of periodic table like Mendeleev periodic table, Mosley periodic table, Modern periodic table etc.

Mendeleev’s Periodic Table

                                                In Mendeleev’s Periodic Table, Mendeleev classify elements according to their atomic masses and arranged these elements in table according to their increasing order of atomic masses.

Mendeleev’s Periodic Law

                                                According to Mendeleev’s Periodic Law – “Physical and chemical properties of elements are periodic function of their atomic masses”.

Mendeleev’s Periodic Table contains seven horizontal rows known as periods and nine vertical columns known as groups.

Modern Periodic Table

                                   Moseley in 1913, after doing many experiments comes to a conclusion that the elements should be arranged as per their atomic no. and not according to atomic masses. As atomic no. is fundamental property of all elements of periodic table. So Mosley gives a new law which is called is Modern Periodic Law.

Modern Periodic Law

                                According to Modern Periodic Law- “Physical and Chemical properties of elements are periodic function of their atomic numbers”.

Long Form of Periodic Table

                                          Bohr Bury invented new periodic table, which is called as Long Form of Periodic Table. This Long Form of Periodic Table is also known as Modern Periodic Table.

Special features of Modern or Long Form of Periodic Table

These below are Special features of Modern or Long Form of Periodic Table

      I.     18 vertical columns known as groups.

      II.     Horizontal rows known as periods.

     III.     Light metals – These are elements of periodic table of group 1 and 2.

     IV.     Heavy metals or Transition metals - These are elements of periodic table of group 3, 4, 5, 6, 7, 

8, 9, 10, 11 and 12.

     V.     Non-Metals – These are elements of periodic table of group 13, 14, 15, 16 and 17.

     VI.     Zero group – These are elements of periodic table of group 18.

🧠 Periodic Table Facts You Should Know

• Hydrogen is the most abundant element in the universe, fueling stars and making up about 75% of elemental mass.

• Helium was first discovered in the Sun's spectrum before it was found on Earth.

• Oxygen makes up about 21% of Earth’s atmosphere and is essential for most life—but it's also highly reactive and corrosive!

• Carbon is the backbone of life and forms more compounds than any other element.

• Nitrogen comprises about 78% of our atmosphere, yet most organisms can't use it directly.

• Iron is the most common element (by mass) in Earth’s core.

• Gold is so malleable that a single gram can be stretched into a thread over 2 kilometers long.

• Gallium melts in your hand—its melting point is around 30°C.

• Mercury is the only metal that is liquid at room temperature.

• Neon doesn’t react with anything—it’s a true loner among elements.

• Tungsten has the highest melting point of all metals: over 3400°C!

• Lithium is used in mood-stabilizing drugs and powerful batteries.

• Bismuth is one of the most diamagnetic elements and forms colorful crystal structures.

• Arsenic was once widely used in medicines and cosmetics (!), despite being highly toxic.

• Radium, discovered by Marie Curie, was once added to drinking water for its supposed health benefits.

• Phosphorus was first discovered by alchemists trying to make gold—from urine.

• Technetium was the first element to be artificially created before being found in nature.

• Francium is so rare that scientists estimate there are only ever a few grams of it on Earth at any given time.

• Chlorine is a greenish-yellow gas with a sharp, suffocating odor.

• Iodine is a shiny purple solid that turns into a violet gas when heated.

• Copper is one of only a few metals with natural color other than silver or gray.

• Cesium reacts explosively with water—even small amounts.

• Fluorine is the most reactive element and can corrode glass, metals, and even humans.

• Silicon is essential in electronics and also makes up much of Earth’s crust.

• Hafnium is used in nuclear reactors due to its ability to absorb neutrons.

For more curious minds, my book "Interesting Facts About All Elements of the Periodic Table" dives deep into every element’s discovery, uses, properties, and surprising stories.

Explore Periodic Table Facts Science Book at

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