When sodium atom reacts with chlorine atoms form a compound, the electron configurations of ions forming the compound are the same as those in which noble gas atoms

A sodium atom has the electron configuration of [ 2,8,1 ] before bonding with a chlorine atom which has the electron configuration of [ 2,8,7 ].

because sodium becomes a one plus ion ( +1 ), it must lose an electron to become stable therefore when bonded the electron configuration becomes [ 2,8 ] this is the same as the noble gas, Neon [ 2,8 ].

because chlorine becomes a minus one ion ( -1 ), it must gain an electron to become stable therefore when boded the electron configuration becomes [ 2,8,8 ] this is the same as the noble gas, Argon [ 2,8,8 ].

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