Halogen - 
	Halogen is the only group on the periodic table that contains elements in all
	three familiar states of matter at STP. All form acid when bonded with hydrogen.
	Most are produced from salts and minerals. Chlorine, bromine and iodine are used
	for disinfectants.   

	Fluorine (F) -
	Has the atomic number 9. At room temperature it is a pale yellow gas. Fluorine is
	the lightest halogen and the most electronegative element, it is very poisonous and
	extremely reactive. it is the 13th most abundant in the Earth's crust and is the 24th
	most abundant element in the known universe.

	Chlorine (Cl) -
	Has the atomic number 17. It is a pale yellow-green gas under standard conditions and
	is the second lightest halogen after fluorine. It has the highest electron affinity
	and is the third highest electronegativity.

	Bromine (Br) -
	Has the atomic number 35. It is a fuming red-brown liquid at room temperature. It is
	corrosive and very toxic with properties between iodine and chlorine. The name comes
	from the Greek meaning of "strong-smelling" or "stench."

	Iodine (I) -
	Has the atomic number 53. It is non-toxic The name comes from the Greek meaning for
	violet or purple because of the color of elemental iodine vapor. Iodine is relatively
	rare due to its high atomic numer and it the heaviest essential element used a lot in
	biological functions. 

	Astatine (At) -
	Has the atomic number 85. It is a radioactive chemical element and is found on earth
	as a result of radioactive decay of some heavier elements. Elemental astatine as never
	viewed by the naked eye because a mass of astatine that big would immediately be vaporized
	by the heat generated by its own radioactivity.

	Ununseptium (Uus) -
	Has the atomic number 117. It is a superheavy artificial chemical element, it is the second
	heaviest element of all of the known elements and is the most recently discovered element.