S-Block

1 Subject: Chemistry Class: XI Chapter: The s-Block components spend concepts 1. The s-block elements of the periodical table ar those in which the last negatron enters the outmost s-orbital 2. Elements of group1 are called alkali metals and elements of group 2 are called alkalescent earth metal 3. Group1 elements: Alkali metals (i) Group 1 elements are called alkali metals because they form hydroxides on reaction with wet which are strongly alkaline in nature (ii) The superior general electronic for alkali metals is [noble gas] ns1 Electronic configuration of alkali metals: Element type Atomic Number Lithium Sodium kB 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: Alkali metals cast come to the largest nuclear and ionic radii in their respective periods of the periodic table. On mov e deck the group, the atomic and ionic radii extend account: As we move in a period, the atomic roentgen and ionic radius tend to change magnitude due to incr peace in the effective nuclear charge. Therefore alkali metals feel largest atomic and ionic radii in their respective group. On mournful down the group at that place is increase in the number of shells .Thus there is an increase in duration between nucleus and outer(prenominal) electrons which eventually increases atomic and ionic radii 2. ionization enthalpies: Alkali metals have the lowest ionization enthalpy in each period. at heart the group, the ionization 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 valency electrons are loosely held by the nucleus. By losing the valence electron, they rise a line stable noble g as configuration. This accounts for their ea! se to lose electrons and accordingly they, have...If you want to get a practiced essay, order it on our website: OrderEssay.net

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