S-Block

1 Subject: Chemistry Class: XI Chapter: The s-Block parts tip 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 be 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 urine which are strongly alkaline in nature (ii) The command electronic for alkali metals is [noble gas] ns1 Electronic configuration of alkali metals: Element type Atomic Number Lithium Sodium chiliad 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 gain the largest nuclear and ionic radii in their respective periods of the periodic table. On move deck the gr oup, the atomic and ionic radii join on explanation: As we move in a period, the atomic spoke and ionic radius tend to shine due to incr hush in the effective nuclear charge. Therefore alkali metals be in possession of largest atomic and ionic radii in their respective group. On locomote down the group at that place is increase in the number of shells .

Thus there is an increase in length 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 nu mber of optic 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 recover a line stable noble gas configuration. This accounts for their ease to lose electrons and accordingly they, have...If you want to get a wide essay, order it on our website: OrderEssay.net

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