Question

5. Write the proper charges so that an alkali metal, a noble gas, and a halogen have the same electron configurations. What is the number of protons in each? Number of electrons in each? How many filled energy levels do each have? Arrange them from smallest to largest IE and explain. Arrange them from smallest to largest radii and explain.

Answer 1

Take 3 examples :: Na+ [alkali metal], F-[halogen], Ne[noble gas]

Na :: has atomic number 11 ,, for F atomic number = 9, Ne atomic number = 10

atom/ion	atomic number	number of proton	number of electron
Na	11	11	11
Na+	11	11	10
Ne	10	10	10
Ne	10	10	10
F	9	9	9
F-	9	9	10

All 3 ions has 10 electron so their configuration will be same

1s2 2s2 2p6

they have completely filled 2 energy levels..

Ionization energy is the energy needed to remove valance electron to form cation.This property\

increases as we move from left to right in a periodic table. Thus metals have least ionization energy,where as noble gases

have highest . Hence arranging them from least to highest

Na > F > Ne

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As atomic size increases down the group and it decreases across the period, Na will be largest

Na > F > Ne

when they form ions , Na+ will have smaller radii than F- ,because number of shells in Na reduces. Also effective nuclear

charge of Na+ increases hence ionic radii in the following order

F- > Na+ > Ne

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