Page 20 - E-Science Prep.2 2024-2025 t1 Unit1_Neat

Group (17) Or (7A): Halogens

- They are known as Halogens

Because halogens means ‘forming salts’ as they react
with metals forming salts.

Ex: 2K + 2 2 KBr

Its location in - On the right side of modern periodic table. They
periodic table
1-Its valency: are elements of group (17) in P- block

-They are monovalent bec. their outermost energy

level contains 7 electrons, so during chemical

reaction they tend to gain 1 electron in order to
complete its outermost energy level and form –ve

ion. − (carry only 1–ve charge)
M + 1e

2-Chemical - They are active elements so, they don’t existin
activity: nature in elementary state bec. they combine

- with other elements except Astatine which is
prepared artificially.
-

2nd Prep. First Term 27
20