describe one property shared by elements form group 17 to group 18
One property shared by elements from group 17 to group 18 is that they all have a complete outermost electron shell, also known as a full valence shell. This makes them stable and less likely to react with other elements to form compounds. Additionally, they all have a relatively high electronegativity, meaning that they are able to attract electrons towards themselves in chemical reactions.
One property shared by elements from Group 17 to Group 18 (also known as Group VIIA to Group 0) is that they all have a full outer electron shell.
In Group 17, also known as the halogens, elements such as fluorine, chlorine, bromine, iodine, and astatine have 7 valence electrons (one less than a full outer shell) and tend to gain one electron to achieve a stable electron configuration. This allows them to form ions with a charge of -1.
In Group 18, also known as the noble gases, elements such as helium, neon, argon, krypton, xenon, and radon all have a full outer electron shell (8 electrons for helium and 8 or 18 electrons for the others). Because of this, noble gases are chemically inert and have very low reactivity, as their electron configuration is already stable. This stability is why they are often called "noble" gases.