3. Classification of Elements and Periodicity in Properties
The organization of elements in the Periodic Table illustrates systematic trends that enhance the understanding of their properties. The development of Periodic Law over time helped establish a foundation upon which elements are classified based on atomic number and electronic configuration, thereby revealing periodic patterns in properties such as atomic radius, ionization energy, and electronegativity. These patterns facilitate predictions about the behavior of elements in reactions and their chemical properties.
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What we have learnt
- The Periodic Table categorizes elements based on atomic number, leading to trends in properties.
- Mendeleev’s Periodic Law, based on atomic weights, was modified to incorporate the modern understanding that properties are periodic functions of atomic numbers.
- Periodic trends help in predicting chemical reactivities and properties of elements.
Key Concepts
- -- Periodic Law
- The properties of elements are periodic functions of their atomic numbers, meaning that elements with similar atomic structure exhibit similar properties.
- -- Atomic Radius
- The size of an atom, which varies periodically across the periodic table, decreasing across a period and increasing down a group.
- -- Ionization Enthalpy
- The energy required to remove an electron from an atom or ion; it generally increases across a period and decreases down a group.
- -- Electronegativity
- A measure of the tendency of an atom to attract a bonding pair of electrons; this value tends to increase across a period and decrease down a group.
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