You are a chemist working in your laboratory. In your storage closet you have a cabinet that holds only samples of pure elements, no compounds. While looking for a sample of lithium (L.), you notice that the label on one bottle has worn off. The
room is at normal temperature. The contents of the bottle are liquid and do not look metallic. What element should you
relabel the bottle as?

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.