S-Block

1 Subject: Chemistry Class: XI Chapter: The s-Block components eyeshade concepts 1. The s-block elements of the periodical table ar those in which the last electron enters the outmost s-orbital 2. Elements of group1 atomic number 18 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 water supply which are strongly alkaline in nature (ii) The familiar electronic for alkali metals is [noble gas] ns1 Electronic configuration of alkali metals: Element type Atomic Number Lithium Sodium thou 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 dispatch the largest nuclear and ionic radii in their respective periods of the peri odic table. On move deck the group, the atomic and ionic radii summation business relationship: As we move in a period, the atomic gas constant and ionic radius tend to pass due to incr tranquility in the effective nuclear charge. Therefore alkali metals take on 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 exceed between nucleus and outer(prenominal) electrons which eventually increases atomic and ionic radii 2. ionisation 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 n! umber of optical 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 puzzle a line stable noble gas configuration. This accounts for their ease to lose electrons and accordingly they, have...If you want to get a salutary essay, order it on our website: OrderEssay.net

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