Group 7: Halogens

reactivity

physical attributes

exists as diatomic molecules = two atoms held together by a single covalent bond, for e.g. F2,Cl2

non-metallic

poor conductors of heat and electricity

toxic and corrosive

'hals' = salt 'gen' = to make

halogens make salts like table salt

Group 7 standings

Fluorine (F)

Chlorine (Cl)

Bromine (Br)

Iodine (I)

Astatine (At)

(MP) -101 (BP) -24 (D) 0.0032 (AP) green gas

(MP) -7 (BP) 59 (D) 3.12 (AP) brown liquid

(MP) 114 (BP) 184 (D) 4.95 (AP) purple/black solid

reactivity

react with both metals and non-metals

product = ionic compound called salt which contains halide ions(X-)

Cl₂ (g)+ Mg(s) = MgCl₂

F₂ (g) + 2Na(s) = 2NaF(s)

uses

sodium chloride (table salt)

sodium fluoride ( in toothpaste)

sodium bromide (disinfectant for swimming pools)

sodium iodide (added to table salt to prevent iodine deficiency)

use as disinfectants and bleaches

kill microorganisms and remove colour

Halogens react with hydrogen to form hydrogen halides which can dissolve in water to form acidic solutions like for example:
H₂(g) + Cl₂ (G) = 2HCl(g) (Hydrogen chloride) 2HCl(g) dissolves in water to make hydrochloric acid

Chlorine used in swimming pools and many types of bleach.

Test: damp blue litmus paper in chlorine gas turns red then bleaches white

(H+) and (Cl-) ions in water and the H+ makes it acidic

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