Question

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> In the modern periodic table, sodium (atomic number: 11) is surrounded by elements with atomic numbers 3, 12, and 19 respectively. Which of these elements have physical and chemical properties resembling sodium?

Answer 1

Elements having the same number of valence electrons possess similar chemical and physical properties. The electronic configuration of sodium is 2, 8, 1.
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The electronic configuration of other elements is:

Atomic Number	Electronic Configuration
3	2, 1
12	2, 8, 2
19	2, 8, 8, 1

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Elements having atomic numbers 3 and 19 will show properties resembling to sodium because they have the same number of valence electrons.
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