Question

why alkali metals put colouration to the flame

Answer 1

alkali metal have lower ionization energy.
when they are exposed to flame the outermost electron gets excited and moves to higher energy level
when this electron come back to the lower energy level or ground state then it releases radition of different wavelength in visible region (coloured )
therefore alkali metal show colouration like
Na- yellow
Rb- red violet etc
may this answer help you

Answer 2

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ᴀʟᴋᴀʟɪ ᴍᴇᴛᴀʟꜱ ʜᴀᴠᴇ ᴠᴇʀy ʟᴏᴡ ᴠᴀʟᴜᴇ ᴏꜰ ɪᴏɴɪꜱᴀᴛɪᴏɴ ᴇɴᴇʀɢy ᴀꜱ ᴄᴏᴍᴩᴀʀᴇᴅ ᴛᴏ ᴏᴛʜᴇʀ ᴍᴇᴛᴀʟꜱ. ꜱᴏ ᴀʟᴋᴀʟɪ ᴍᴇᴛᴀʟꜱ ᴇᴀꜱɪʟy ɢᴇᴛ ᴇxᴄɪᴛᴇᴅ ᴀɴᴅ ɪᴍᴩᴀʀᴛ ᴄᴏʟᴏᴜʀ ᴛᴏ ꜰʟᴀᴍᴇ.⠀⠀⠀⠀⠀⠀⠀

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