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प्रश्न
Beryllium and magnesium do not give colour to flame whereas other alkaline earth metals do so. Why?
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उत्तर
When an alkaline earth metal is heated, the valence electrons get excited to a higher energy level. When this excited electron comes back to its lower energy level, it radiates energy, which belongs to the visible region. Hence, the colour is observed. In Be and Mg, the electrons are strongly bound. The energy required to excite these electrons is very high. Therefore, when the electron reverts back to its original position, the energy released does not fall in the visible region. Hence, no colour in the flame is seen.
संबंधित प्रश्न
Discuss the general characteristics and gradation in properties of alkaline earth metals.
The product obtained as a result of a reaction of nitrogen with CaC2 is ______.
Assertion: Generally alkali and alkaline earth metals form superoxides.
Reason: There is a single bond between O and O in superoxides.
Assertion: BeSO4 is soluble in water while BaSO4 is not
Reason: Hydration energy decreases down the group from Be to Ba and lattice energy remains almost constant.
Alkaline earth metal (A), belongs to 3rd period reacts with oxygen and nitrogen to form compound (B) and (C) respectively. It undergoes metal displacement reaction with AgNO3 solution to form compound (D). Identify A, B, C and D.
Why alkaline earth metals are harder than alkali metals?
When sodium is dissolved in liquid ammonia, a solution of deep blue colour is obtained. The colour of the solution is due to ______.
Identify the correct formula of halides of alkaline earth metals from the following.
(i) BaCl2.2H2O
(ii) BaCl2.4H2O
(iii) CaCl2.6H2O
(iv) SrCl2.4H2O
Discuss the trend of the following:
Thermal stability of carbonates of Group 2 elements.
Discuss the trend of the following:
The solubility and the nature of oxides of Group 2 elements.
What is the structure of BeCl2 molecule in gaseous and solid state?
Assertion (A): Beryllium carbonate is kept in the atmosphere of carbon dioxide.
Reason (R): Beryllium carbonate is unstable and decomposes to give beryllium oxide and carbon dioxide.
An element of group 2 forms covalent oxide which is amphoteric in nature and dissolves in water to give an amphoteric hydroxide. Identify the element and write chemical reactions of the hydroxide of the element with an alkali and an acid.
Alkaline earth metals show ______.
MgBr2 and Mgl2 are soluble in acetone because of ______.
PbCl4 exists but PbBr4 and Pbl4 do not because of ______.
