INTRODUCTION

Element

Symbol

Atomic number

 Electronic      configuration

Charge of ion

Valency

State at Room Temperature

Fluorine

Chlorine

Bromine

Iodine

Astatine

F

Cl

Br

I

At

9

17

35

53

85

2:7

2:8:7

2:8:18:7

2:8:18:18:7

2:8:18:32:18:7

F-

Cl-

Br-

I-

At-

1

1

1

1

1

Pale yellow gas

Pale green gas

Red liquid

Grey Solid

Radioactive