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Classification of Elements

Class 10: Science

Classification of Elements, Periodic Table, Mendeleev Periodic Table, Modern Periodic Table, Electronic Configuration of Elements Based on Sub-shell, Classification of Elements in Modern Periodic Table, Characteristics of Period and Group in Periodic Table

Classification of Elements

The process of arranging the elements into groups based on their similar and dissimilar properties is called the Classification of Elements. The table formed after the classification is called the Periodic Table.

 

Periodic Table

The systematic arrangement of elements in different groups and periods based on their properties is called the periodic table.

 

Mendeleev Periodic Law

In 1869 Russian chemist Dmitri Mendeleev created a periodic table and he arranged elements with their increasing order of atomic weight.

The Mendeleev’s Periodic Law states that,

“The physical and chemical properties of elements are the periodic functions of their atomic weights.”

Modern Periodic Law

In Mendeleev’s periodic table, there were some drawbacks. So, in 1913 English Physicist Henry Mosley found that the physical and chemical properties of elements are based on their atomic number, and he created the modern periodic table. 

The modern periodic law states that,

“The physical and chemical properties of elements are the periodic functions of their atomic numbers.”

 

Electronic Configuration Base on Sub-shell

What is Subshell?

The subdivision of electron shells is called a subshell. There are four subshells denoted by s, p, d, and f. The s subshell can have a maximum of 2 electrons, the p subshell can have a maximum of 6 electrons, the d subshell can have a maximum of 10 electrons, and finally, f subshell can have a maximum of 14 electrons. 

Relationship between shells and subshells

SNShellSubshell/sNotationNumber of Electrons
1K (1)s1s2
2L (2)s & p2s & 2p2 + 6 = 8
3M (3)s, p & d3s, 3p & 3d2 + 6 + 10 = 18
4N (4)s, p, d & f4s, 4p, 4d & 4f2 + 6 + 10 + 14 = 32
5O (5)s, p, d & f5s, 5p, 5d & 5f2 + 6 + 10 + 14 = 32

 

Classification of Elements in Modern Periodic Table

In the modern periodic table, elements are grouped based on their properties. Let’s explore where metals, metalloids, and nonmetals are placed:

1. Metals:

Metals are predominantly found on the left side of the periodic table.

They include:

Alkali metals (Group 1): Highly reactive metals like lithium (Li) and sodium (Na).

Alkaline earth metals (Group 2): Elements such as magnesium (Mg) and calcium (Ca).

Transition metals (Groups 3–12): Examples include iron (Fe), copper (Cu), and gold (Au).

Lanthanides (Rare Earth Metals): These are placed below the main table.

Actinides: Also placed below the main table.

2. Metalloids:

Metalloids (or semimetals) exhibit properties intermediate between metals and nonmetals.

They form a zigzag line on the periodic table, separating metals from nonmetals.

Notable metalloids include Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te)

3. Nonmetals:

Nonmetals are primarily located on the right side of the periodic table.

They include:

Halogens (Group 17): Fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

Noble gases (Group 18): Elements like helium (He), Neon (Ne), and xenon (Xe).

Other nonmetals such as oxygen (O), nitrogen (N), carbon (C), and sulfur (S).

 

Characteristics of Period and Group in Periodic Table

In Group (Vertical): From Top to Bottom 

  1. Valency: The valency of elements remains the same.
  2. Atomic Size: Atomic size increases
  3. Electropositivity and Electronegativity: Electropositivity Increases, Electronegativity Decreases
  4. Chemical Reactivity: Increases

In Period (Horizontal): From Left to Right 

  1. Valency: Varies
  2. Atomic Size: Decreases
  3. Electropositivity and Electronegativity: Electropositivity Decreases, Electronegativity Increases
  4. Chemical Reactivity: For metals reactivity Decreases, For Nonmetals reactivity Increases

 

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