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Periodic Table

The periodic table is an arrangement of all known elements in order of increasing atomic number and recurring chemical properties. 

  • To facilitate the study of elements, all known elements must be arranged according to their properties, with related elements falling into the same groups and dissimilar elements being separated. This process is known as element classification.
  • The Mendeleev periodic table, an earlier version of the periodic table, was based on the law that “Physical and chemical properties of elements are the periodic function of their atomic masses”.
  • Mendeleev’s (1861) scientific classification of chemical elements based on their masses or atomic weights has been disproved, leading to the development of the modern periodic table law.
  • The Modern periodic table, long form of the periodic table, is based on the law that “Physical and chemical properties of elements are the periodic function of their atomic numbers”.
  • The classification of elements in the long version of the periodic table is based on the order of increasing atomic numbers or Periodicity (i.e., periodic repetition of attributes).
  • Periodicity is the recurrence of similar-behaving elements at regular intervals when these elements are grouped in ascending order of their atomic numbers.
  • There are 18 vertical columns of elements known as groups and seven horizontal rows of elements known as seven periods. The modern periodic table, therefore, contains 18 groups, which are numbered from 1 to 18.
  • The periodic table contains interesting facts that clearly illustrate the relationship between electronic structure and periodic accommodation capacity as the purpose of chemical elements.
  • The atomic structure or the electrical arrangement of an element determines its periodicity.
  • As a result, the recurrence of comparable features results from repeated electrical configurations or atomic structures. Thus, the repetition of an analogous electrical arrangement is the cause of periodicity.
  • The many kinds of metals and non-metals in chemistry are arranged into the s, p, d, and f-block on the periodic table by the modern periodic law, which is based on the atomic number and valence shell electron configuration of elements.
  • s- block elements: The arrangement of electrons in the periodic table gives rise to the designation “s-block element” in which the valence electron enters the ns-orbital and gradually fills it by the configuration rules. S-block elements are the 1st and 2nd group elements.
  • p-block elements: The last electron in a P block element enters one of the three p-orbitals of its corresponding shell. As a p-subshell has three degenerate p-orbitals, each of which may hold two electrons, there are six groups of p-block elements. P-block elements are those that belong to groups 13 to 18. ns2 np1-6 is the general electrical configuration for these elements.
  • d-block elements: d-block elements are those that are found from Group 3 to Group 12 in the middle of the periodic table. Because the final electron gets to the d-orbital of the penultimate shell, they are known as a “d-block” element.
  • f-block elements: The f-block elements, also known as inner transition elements, are those whose final electron to enter the f-orbital is known. In addition to having electrons in the outermost orbital, these elements also have electrons (0 to 1) in the penultimate energy level’s d orbital and (1 to 14) in the f orbital. In the f-block, there are mainly two series that correspond to the filling of the 4f and 5f orbitals.

Reactions of Halide Ions (A Level Chemistry Revision Notes)

July 13, 2026May 12, 2026 by Jyoti Bashyal
Reactions of Halide Ions

A halide ions is a negatively charged anion formed by a halogen atom. They have a (-1 ) charge. A halide is also a compound composed of a halogen atom bonded to a less electronegative species. Halide Ions include fluoride … Read more

Chemical Properties of Halogen Elements and Hydrogen Halides (A Level Chemistry Revision Notes)

July 13, 2026May 11, 2026 by Jyoti Bashyal
Chemical Properties of Halogen Elements and Hydrogen Halides

Group 17 of the periodic table is named Halogens as they all produce sodium salts with similar properties. The chemical properties of halogens [ fluorine (F), chlorine (Cl), bromine (Br), and iodine (I)] are summarized below. Oxidizing Properties of Halogen … Read more

Physical Properties of Group 17 Elements (A Level Chemistry Revision Notes)

July 13, 2026May 10, 2026 by Jyoti Bashyal
Physical Properties of Group 17 Elements in Periodic Table

Group 17 of the periodic table is named Halogens as they all produce sodium salts with similar properties. In Greek, halo means salt, and genes mean generating, so salt-producing is a collective meaning of the term. Halogens are also known … Read more

Trends in the Properties of Group 2 (Alkaline Earth) Metals (A Level Chemistry Revision Notes)

July 13, 2026May 9, 2026 by Jyoti Bashyal
Trends of the Properties of Group 2 Metals (Alkaline Earth Metals)

Group 2 elements (alkaline earth metals) all have two electrons in their outermost principal quantum shell. All Group 2 metals can form ionic compounds in which they donate their two outermost electrons (acting as reducing agents) to form a +2 … Read more

Periodicity of chemical properties of the elements in Period 3 (A Level Chemistry Revision Notes)

July 13, 2026May 8, 2026 by Jyoti Bashyal
Chemical Properties Of Elements in Period 3

According to modern periodic law- The physical and chemical properties of the elements are the periodic function of their atomic numbers and electronic configuration. Chemical properties are observed during chemical reactions and are concerned with the electrons of the outer … Read more

Periodicity of physical properties of the elements in Period 3 (A Level Chemistry Revision Notes)

July 13, 2026May 7, 2026 by Jyoti Bashyal
Physical Properties of Elements in Period 3

The elements of period 3 are placed in the third row of the periodic table. The elements positioned in period 3 are Sodium (Na), Magnesium (Mg), Aluminium (Al), Silicon (Si), Phosphorus (P), Sulphur (S), Chlorine (Cl), and Argon (Ar). Firstly, … Read more

Transition Elements (A Level Chemistry Revision Notes)

July 13, 2026March 1, 2026 by Jyoti Bashyal
Transition Elements - General Properties and Uses

The transition metals, which are located in the middle of the periodic table, make up the largest group of elements there. Additionally, the lanthanides and actinides, two rows of elements below the main body of the periodic table, are particular … Read more

Periodic Table: Definition, Terms, 118 Elements, Applications

June 24, 2025 by Jyoti Bashyal
Simplified Periodic Table of Elements

A vital component of contemporary chemistry is the periodic table. The periodic table was designed to provide a highly informative representation of the chemical elements. Each element is placed in the periodic table with particular parameters in mind. For many, … Read more

Lead (Pb) Element: Properties, Reactions, Uses

February 6, 2025February 5, 2025 by Jyoti Bashyal
Lead (Pb) Element

The atomic number of Lead is 82. It is found in Group 14 (carbon group) and Period 6 of the periodic chart. The symbol ‘Pb’ represents it. It gets its name from the Anglo-Saxon word “lead,” and the Latin word … Read more

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