Without looking at a periodic table, list as many halogens as you can. (There are four common ones.)

Halogens are a group of elements found in Group 17 of the periodic table. They are known for their high reactivity, particularly with alkali and alkaline earth metals, forming salts. The four most common halogens are fluorine, chlorine, bromine, and iodine, each exhibiting distinct physical and chemical properties.

Chemical reactivity refers to the tendency of a substance to undergo chemical changes when it interacts with other substances. Halogens are highly reactive due to their seven valence electrons, which makes them eager to gain one more electron to achieve a stable octet configuration. This reactivity is a key characteristic that defines their behavior in chemical reactions.

The states of matter refer to the distinct forms that different phases of matter take on. Halogens exist in different states at room temperature: fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid. Understanding these states helps in predicting their behavior and applications in various chemical processes.