someone help answer a hard chemistry question for me please

on the academic forum there are not that many active users
im struggling very much on chemistry and would appreciate some input as to this question

a)
state and explain the trend in melting points of the elements down Group II from Be to Ba. decreases????

b)State the trend in reactivity with water of the elements down group II from Be to Ba. Write an equation for the reaction of magnesium with steam and an equation for the reaction of strontium in water

c)sulfates of the group II elements from Be to Ba have different solubilities. Give the formula of the least soluble of these sulfates and state one use that depends upon insolubility of this sulfate

please!

on the academic forum there are not that many active users
im struggling very much on chemistry and would appreciate some input as to this question

a)
state and explain the trend in melting points of the elements down Group II from Be to Ba. decreases????

please!

on the academic forum there are not that many active users
im struggling very much on chemistry and would appreciate some input as to this question

a)
state and explain the trend in melting points of the elements down Group II from Be to Ba. decreases????

b)State the trend in reactivity with water of the elements down group II from Be to Ba. Write an equation for the reaction of magnesium with steam and an equation for the reaction of strontium in water

c)sulfates of the group II elements from Be to Ba have different solubilities. Give the formula of the least soluble of these sulfates and state one use that depends upon insolubility of this sulfate

please!

As the group is descended the atoms (and hence ions) become bigger for each respective element. This means that the charge density of the ions decreases as the group is descended and so the attraction between the delocalised electrons and metal cations is weaker. In addition smaller ions are able to fit closer together which further increases the strength of the metallic bonds as the force between the ions is given by kQ^2/d^2, where d is the distance between the charges and Q being the charge on each metal ion. This means the melting points decrease down the group.


When reacting with water, the metal atoms must lose electrons to form positive ions which, in most cases, will be attacked by the OH- nucleophile of the water molecule. Hence, the ease with which the atoms are able to lose electrons determines the feasibility of the reaction. As the group is descended, the atoms become larger and the attraction beween the nucleus and the outer electrons is weakened as a result. Additionally there is the effect of increased shielding from the inner electrons. This means that reactivity increases as the group is descended.

Magnesium reacts with steam to produce the oxide, whereas strontium (being slightly more reactive) may be able to form a hydroxide (Im not sure about this).


Solubility depends on whether the energy required to break the ionic lattice can be recouped in the subsequent hydration of the newly formed ions. So, we would expect that solubility would be greater for species which have a small (more positive) lattice enthalpy and a large negative value for hydration of the ions. The lattice enthalpy of the salt depends on the strength of the bond between the metal ion and the sulphate ion, but there is little difference in the strength of such bonds for group 2 sulphates as the sulphate ion is large relative to the cation so with changing cation size there is little effect on the bond strength and lattice enthalpy. This means that the most soluble salt will be the one containing the ion with the greatest hydration enthalpy, which will be the smallest ion as this will have the greatest charge density. Therefore, solubility increases up the group with Beryllium sulphate being most soluble.

The least soluble is Barium Sulphate (radium is radioactive)