Group 7 Halogens

•Most reactive non metallic group

•Diatomic

•High EN

•At room temp.

o Fluorine (very reactive)       Pale yellow-G

o Chlorine                                  Greenish-G

o Bromine                                  Red-Brown-G

 o Iodine                                     Black-S

Astanine is radioactive, v. dangerous

• Increases down group  

• Extra filled O.E.S

• Increasing nuclear charge ,increased shielding  

• Decreases down group

• attrac. of nuc. to bond. elec.

• Affected by:

 -Elec. shells, more shells therefore more shielding,inc. nuc. charge.

-Atomic radius, elec. further from nuc., nuc. attract. reduced

-Atomic no., nuc. charge increases counteracted ,increase in elec. shells.            

• Increase down group
• The halogens bond as diatomic molecules ,intermolecular forces will be weak VdW attractions (instantaneous – induced dipole).
• The atomic radius increases down group, molecules have a greater SA
• The bigger SA = greater surface contact, intermolecular forces are larger.
• Needs more energy,so BP is increased.

• Decreases down the group
• The oxidising ability depends on:

          1) The strength of the X–X bond (this must break to form ions).

                This increases going down the group (the F–F bond is very weak).

          2) The energy released when the X– ion goes into solution.

                This decreases down the group, as the charge density of the ion. 

                increases, so larger ions benefit less 

          3) The affinity of an X atom for an electron (to form an X– ion).

              This doesn’t vary very much, so has little effect on the oxidising

                power.