non metals on right side of the periodic table. This means metallic character decreases while non metallic character increases as we move along a period (from left to right).

Let us take group 14 (IVA) elements.

IVA group: C     Si     Ge     Sn     Pb

Here also we know that carbon is nonmetal. Si and Ge are metalloids. Sn and Pb are metals.

So we find nonmetals particularly at the right hand side top and metals at the left and right hand side bottom of the periodic table. This means metallic character increases while non metallic character decreases in a group as we move from top to bottom

KEY WORDS

Triad, Octave, Periodic Law, Periodic table, period, group, Lanthanides, Actinides, Element family, Metalloids, Periodicity, Atomic radius, Ionization energy, Electron affinity, Electronegativity, Electropositivity

What we have learnt

• Elements are classified on the basis of similarities in their properties.

• Dobereiner grouped the elements into Triads and Newlands gave the law of Octaves.

• Mendeleeff’s Periodic law: The physical and chemical Properties of the elements are the periodic functions of their Atomic Masses.

• Moseley’s Periodic law : The physical and chemical properties of the elements are the periodic functions of their Atomic numbers.

• Modern Periodic Law: The Physical and chemical Properties of the elements are the periodic functions of their Electronic Configurations.

• Anomalies in arrangement of elements based on increasing atomic mass could be removed when the elements were arranged in order of increasing atomic number, a fundamental property of the element discovered by Moseley.

• Elements in the Modern Periodic table are arranged in 18 groups and 7 periods.

• Elements are classified into s, p, d, f blocks, depending upon to which sub shell, the differentiating electron enters in the atom of the given element.


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