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The s-block Elements — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryThe s-block Elements3 Marks
Question
Why do beryllium and magnesium not impart colour to the flame in the flame test?
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Answer

Beryllium and magnesium do not give colour to flame because they (Be and Mg) have a small size and very high ionisation enthalpies. The enthalpy of the flame is not sufficient to excite their electrons to higher energy levels. Other alkaline earth metals impart colour to the flame because they have fairly low ionisation enthalpies, so electrons in their atoms can be easily excited by the enthalpy of the flame. The excited electrons on returning to their original positions lose enthalpy in the form of coloured light.

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