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Model Paper 9 — Chemistry STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 ScienceChemistryModel Paper 92 Marks
Question
Why are elements at the extreme left and extreme right the most reactive?
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Answer

Elements at the extreme left and extreme right of periodic table are most reactive. It is due to following reasons:
1. Alkali metals are present at extreme left end of periodic table. Due to greatest atomic size of alkali metals, their ionisation enthalpy is low. These metals can easily lose electrons to form cations. Hence, these metals are very reactive in nature.
2. On the other hand, Halogens (group $17^{\text {th }}$ ) are present on extreme right side of periodic table (Noble gases, group $18^{\text {th }}$, are stable). Due to smallest atomic size of halogens, their electron gain enthalpy is very high. Therefore, these elements can form anions easily by gaining the electrons. So, These elements are also reactive.

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