electronic configuration in periods short note
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Electronic Configuration in Periods. The value of n, the principal quantum number, for the valence shell is the period of the element. Different energy levels can accommodate different number of electrons. ... Thus, the first period with n = 1 can hold up to 2 elements by filling the lowest level 1s.
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Configuration Trends Across Periods And Groups
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Electronic Configuration in Periods and Groups
The electronic configuration of an atom is the numerical representation of the arrangement of electrons distributed in the orbitals of the atom. This determines the position of an element in the periodic table and in turn its chemical behavior. It explains how the atoms are held together by the chemical bonds, and the peculiar trends which are observed in the rows and columns of the periodic table. In this article, we will discuss the electronic configuration of elements in the same periods and groups of the periodic table.
Electronic Configuration in Periods
The value of n, the principal quantum number, for the valence shell is the period of the element.
Different energy levels can accommodate different number of electrons.
The maximum number of electrons that a given energy level can accommodate is given by 2n2, where n is the energy level. So the first energy level (K shell) can hold up to 2 electrons, second level (L shell) can hold up to 8 electrons, and third level (M shell) can also hold 18 electrons and so on.
Thus, the first period with n = 1 can hold up to 2 elements by filling the lowest level 1s. The elements are Hydrogen and Helium with electronic configuration 1s1 and 1s2 This marks the complete filling of K shell.
The second period starts with Lithium and Beryllium which have 3 and 4 electrons and hence the last electrons enter the level 2s and they have an electronic configuration of 1s22s1 and 1s22s2 This is followed by the start of the 2p orbital filling. It starts with Boron (1s22s22p1) and ends with Neon (1s22s22p6) which marks the completion of L shell. Thus, 8 elements are present in the second period.