Question

Why are the elements fluorine (F) , chlorine (Cl) , and bromine (Br) all found in the same group within the periodic table? A) They all exist as gases at 20°C) . B) They all react with the noble gases. C) They have the same chemical properties. D) They are all non-metals that form 1+ ions.

Answer 1

Fluorine, Chlorine, Bromine, Iodine and Astatine are representing the family of elements called : halogens.
Halogens:
- all have 7 electrons in their outer shell,
- are very reactive elements,
- form - 1 ions.
Answer: C ) They have same chemical properties. 

Answer 2

A  they all exist as gases at 20c