He left vacant spaces in the original table for elementsto be discovered. (Say – 2010)Ī) Discuss about the main features of Mendeleev’s periodic table.Ĭ) Give the name for the element with atomic number 112.Ī) Mendeleev’s periodic table made the study of chemistry of elements easier and systematic.

Hence electron gain enthalpy of F is less negative that of Cl.ĭevelopment of Periodic Table have made the study of elements and their compounds easier. However, adding an electron to the 2p orbital leads to greater repulsion than adding an electron to the larger 3p or bital. So, atomic radius decreases from left to right.Ĭ) Within a group electron gain enthalpy becomes less negative down a group. It is because within the period the outer electrons are in the same valence shell and the effective nuclear charge increases as the atomic number resulting in the increased attraction of the electrons to the nucleus. Consequently, it is easier to remove the fourth 2p electrons from oxygen than it is, to remove one of the three 2p electrons from nitrogen.ī) The atomic size generally decreases across a period. (Hund’s rule) whereas in the oxygen atom, two of the four2p electrons must occupy the same 2p orbitals resulting in an increased electron repulsion. This arises because in nitrogen atom, three 2p electrons reside in different atomic orbitals. (March – 2009)ī) State the modern periodic law of elements.Ī) Mendeleev’s Periodic law : The physical and chemical properties of elements are periodic functions of their atomic mass.ī) Modern Periodic law: The physical and chemical properties of elements are a periodic function of their atomic numbers.Īccount for the following: (March – 2010)Ī) Ionization enthalpy of nitrogen is greater than that of oxygen.ī) Atomic radius decreases from left to right in a period.Ĭ) Electron gain enthalpy of F is less negative than that of Cl.Ī) Ionisation enthalpy of nitrogen is greater than that of oxygen. Kerala Plus One Chemistry Chapter Wise Previous Questions Chapter 3 Classification of Elements and Periodicity in PropertiesĪ) Who introduced the periodic law of elements for the first time? State the law. Here we have given Plus One Chemistry Previous Questions Chapter 3 Classification of Elements and Periodicity in Properties. Plus One Chemistry Chapter Wise Previous Questions Chapter 3 Classification of Elements and Periodicity in Properties is part of Kerala Plus One Chemistry Chapter Wise Previous Year Questions and Answer.

Ns2 np3 valence shell