Elements in group 17 have similar properties because they all have the name number of what

Elements in group 17 have similar properties because they all the same number of electrons and valence electrons.

The atoms of the elements in Group 17 (also called the halogens) have seven electrons in their highest occupied energy level (the outer shell). This is why their chemical properties are similar.

Explanation:

They all form acids when combined with hydrogen.

They are all fairly toxic.

They readily combine with metals to form salts.

They have seven valence electrons in their outer shell.

They are highly reactive and electronegative.

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-