Question

Why group 1 element combine with group 17 element to form ionic compounds

Answer 1

Answer:

first you need to know that atoms are the most stable when they attain an octet structure, which means having 8 outermost shell electrons.

for group 1 elements, they have 1 electron on their outermost shell, so they are very reactive. eg, Na is very reactive and cannot exist on its own under room conditions, so it loses one electrons and form Na+ ion, hence attaining an electronic configuration of 2,8, which is octet.

for group 7 elements, they have 7 electron on their outermost shell, so they wanna gain 1 electron in order to attain an octet structure. eg Cl gains one electron to become Cl- ion, hence attaining an electronic configuration of 2,8,8, which is also octet.

taking Na and Cl as example, the electron lost from Na is transferred to Cl, hence Na+ and Cl- are formed. since Na+ ions and Cl- ions are oppositely charged, there is a strong attraction force between them. the attraction force is the ionic bond. NaCl is the ionic compounds.

this works the same for other elements.

Explanation: