Question

Are all elements in the group $17$ metals?

Answer 1

The elements present in the group $17$ are Fluorine, Chlorine, Bromine, Iodine and Astatine. These are present in the p block of the modern periodic table. There are six groups in the p block. The p block contains metals, nonmetals and metalloids.

Complete answer:
The group $17$ elements are called halogens and are very reactive in nature, in general, fluorine being the most reactive. The other groups of p block are – group $13$ (boron family), group $14$ (carbon family), group $15$ (nitrogen family), group $16$ (oxygen family), group $18$ (noble gases).
Halogens are definitely non-metals. They are oxidizing in nature and have negative charge on them in ionic form. They exist in gaseous form (eg. Chlorine), in liquid state (eg. Bromine). They react with metals like sodium to form halides (eg. Sodium chloride). They are not hard, malleable, ductile as metals do, so they cannot be considered as metals.
Halogens exhibit the properties of nonmetals like softness, liquid or solid state, oxidising nature etc. They have valency of $- 1$, i.e. they either accept or share one electron to form compounds with other elements.
Hence, the elements of group $17$ of the periodic table are nonmetals and metals.

Note:
Astatine though is classified as a metalloid because it has some properties a metal would have. The reactivity of astatine is also uncertain. Fluorine is highly reactive and reacts with hydrogen to form hydrogen fluoride, the strongest acid. Bromine exists in liquid form as brown liquid. Chlorine is also a reactive element and is a major part of CFC.