化學一問...........

Question

Rubidium ( Rb ) and potassium belong to the same group in the periodic table . The relative atomic mass of rubidium is larger than that of potassium .
a ) Explain whether rubidium is more reactive than potassium .
b ) Suggest how rubidium can be stored safety in the laboratory .
c ) Suggest ONE satety precaution for handling rubidium in the laboratory .

Answer 1

a)
Rubidium is more reactive than potassium.
The atomic size of rubidium is greater than potassium, because rubidium has a greater number of shells. The electron in the outermost shell of rubidium is farther apart from the nucleus, and is thus experienced a weak nuclear attraction. Therefore, the electron in the outermost shell of rubidium is lost to give a cation more readily.

b)
It is stored in paraffin oil in a reagent bottle.

c)
Wear gloves, etc.

Answer 2

a) Reactivity or the ease with which these elements give off their electrons increases with the size of the atoms. The size of the atom increases from Li to Fr. The outermost electron is less loosely bound in Rb than in K, as in Rb the distance between the last electron and the positive nucleus is large; this makes the attractive force binding or holding the electron to be less.

b)Rubidium reacts violently with water and can cause fires. To ensure both safety and purity, this element must be kept under a dry mineral oil, in a vacuum or in an inert atmosphere.

c)Wear the safety goggles or use it under vacuum.