Which elements has a total of two shells, with three electrons in its valence shell?

Which elements has a total of three shells, with four electrons in its valence shell?

Which elements has two shells, both of which are completely filled with electrons?

Which element has twice as many electrons in its second shell as in its first shell?

Name two elements that have two electrons in their outermost shells.

Name three elements with filled outermost shells.

Name three elements that have a single electron in their outermost shells.

Which halogen has the highest electron gain enthalpy and which halogen has the highest Electronegativity?