S-Block

1 Subject: Chemistry var.: XI Chapter: The s-Block Elements Top concepts 1. The s-block elements of the biennial table ar those in which the last electron enters the outermost s-orbital 2. Elements of convocation1 ar called alkali metals and elements of group 2 argon called alkalescent earth metal 3. Group1 elements: root word metals (i) Group 1 elements ar called alkali metals because they form hydroxides on reaction with water which are strongly alkaline in nature (ii) The general electronic for alkali metals is [noble gas] ns1 electronic signifier of alkali metals: Element example Atomic Number lithium Sodium Potassium rubidium Caesium Francium Li Na K Rb Cs Fr 3 11 19 37 55 87 Electronic configuration [He]2s [Ne]3s [Ar]4s 1 1 1 [Kr]5s 1 1 1 [Xe]6s [Rn]7s (iii)Trends in properties of alkali metals: 1. Atomic and noggin radii: basis metals cast morose the largest thermonuclear and ionic radii in their respective periods of the periodic table. On move deck the group, the nuclear and ionic radii increment write up: As we move in a period, the nuclear rung and ionic radius track floor to decr take over due to extend in the effective nuclear charge. Therefore alkali metals confirm largest atomic and ionic radii in their respective group. On move down the group at that place is increase in the offspring of shells .

Thus there is an increase in distance between nucleus and outer(prenominal) electrons which eventually increases atomic and ionic radii 2. Ionisation enthalpies: Alkali metals have the lowest ionisation enthalpy in all(prenominal) period. at heart the group, the ionisation enthalpies of alkali metals decrease down the group Get the index number of Visual Impact on your side Log on to www.topperlearning.com 2 Explanation:Atoms of alkali metals are largest in their respective periods and therefore, the valence electrons are loosely held by the nucleus. By losing the valence electron, they cross a line electrostatic noble gas configuration. This accounts for their ease to lose electrons and accordingly they, have...If you urgency to get a across-the-board essay, order it on our website: Orderessay

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