Melting point and boiling point
The halogens have low melting points and boiling points. This is a typical property of non-metals. You can see from the graph that fluorine, at the top of Group 7, has the lowest melting point and boiling point in the Group. The melting points and boiling points then increase as you go down the Group.
State at room temperature (20°C)
Fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. You should remember this trend down the periodic table - the top two elements are gases, the bottom two are solids and the middle element is liquid.
Colour
The halogens become darker as you go down the group. Fluorine is very pale yellow, chlorine is yellow-green and bromine is red-brown. Iodine crystals are shinygrey, but easily turn into a dark purple vapour when they are warmed up.
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