why is thallium soft metal ?

Question

rane · Answer

@jiteshmeghwal9

jiteshmeghwal9 · Answer

In my opinion because of its appearance & characteristics.

melting point=$302^0$c
boiling point=$1,457^0$c
density=$11.8g/cm^3$

Thallium metal is so soft that it can easily be cut with a knife. It has a metallic luster that slowly tarnishes upon exposure to air to give the metal a bluish-gray appearance (caused by the formation of Tl 2 O 3 ). The thin layers of surface oxide prevent further oxidation . However, in moist air or water, the soluble hydroxide TlOH is formed. Thallium can exist in two oxidation states, (I) and (III). When heated in air, the metal oxidizes to Tl 2 O. Thallium reacts vigorously with the halogens , forming dihalides of composition 2Tl X 3 where X = fluorine, chlorine, or bromine. Thallium is rapidly dissolved in nitric acid but rendered passive in sulfuric and hydrochloric acids due to the formation of insoluble Tl(I) salt

rane · Answer

that paragraph doesn't answer Why is it soft metal.... 
its tells us its characteristics

jiteshmeghwal9 · Answer

http://en.wikipedia.org/wiki/Thallium wikipedia will give the detailed concept :)

rane · Answer

i did read that but it also doesn't states y its soft

jiteshmeghwal9 · Answer

then u should ask it at http://in.answers.yahoo.com/