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  Diagonal Relationship between Beryllium and Aluminium The ionic radius of Beryllium (Be 2+) is estimated to be nearly 31 pm; the charge/radius ratio Or e/m ratio is nearly the same as that of the Al 3+ ion. Hence beryllium resembles aluminium in these ways. Some of the similarities are given below: » Like Aluminium, Beryllium(be) is not readily attacked by acids H+ donor because of the formation of an oxide film on the surface of the metal by reacting with oxygen, i.e. they are rendered passive by nitric acid. » Beryllium hydroxide[[Be(OH)4]2] dissolves in excess of alkali to give a beryllate ion, [ Be(OH)4]2– just as aluminium hydroxide[Al(OH)3] gives aluminate ion, [Al(OH)4] » The chlorides of metals beryllium and aluminium have Cl– bridged chloride structure in vapour phase. Both the chlorides are soluble in organic solvents and are strong as Lewis acids They are used as Friedel Craft catalysts. » Beryllium(Be) and aluminium(Al) ions have strong tendency to form complexes, (Be...

                  QUANTUM NUMBERS  Orbitals represent regions in the space around the nucleus where the probability of finding the electron is maximum. A large number of electron orbitals are possible in atom. These can be distinguished by their size, shape and orientation of the orbitals. To describe each electron in an atom in different orbitals, we need a set of three numbers known as quantum numbers. These are designated as n, l and m. In addition to these three numbers another quantum number is also needed which specifies the spin of the electron. These four numbers are called quantum numbers. These are discussed below: 1. Principal quantum number (n) :  This quantum number determines the main energy shell or level in which the electron is present. It is denoted by n. It can have whole number values starting from 1 such as n = 1, 2, 3, 4 ... This quantum number also identifies as shell. The shell with n 1 is called the first sh...

  Difference   between Electromagnetic Waves and Matter Waves » Electromagnetic waves 1. Electromagnetic waves are associated with electric and magnetic fields perpendicular to each other and to the direction of propagation of radiation. 2. Electromagnetic waves can be radiated into space or emitted. 3. They do not require any medium for propagation i.e., these waves can pass through vacuum. 4. All electromagnetic waves travel with the same velocity.  5. The velocity of all electromagnetic waves is equal to that of light (3 x 108 m/s). 6. The wavelengths of electromagnetic radiation are much large .   » Matter waves 1. Matter waves may not be associated with electric and magnetic fields. 2. Matter waves are neither radiated into space nor emitted by the particles. These are simply associated with the particles 3. They require medium for propagation i.e., these waves cannot pass through vacuum. 4. Matter waves travel with different vel...

A tower, x metre, has a flagstaff at its top. The tower and flagstaff subtends equal angles at a point distant y metre from the foot of the tower. Then find the length of the flagstaff ( in metre). 

Ques 15 : What do you mean by a precipitation reaction? Explain by giving examples. Ans 15 : A reaction in which an insoluble solid (called precipitate) is formed is called a  precipitation reaction.  It get deposited at the bottom of the container. It is denoted by ↓. For example:      Na 2 Co 3 +   CaCl 2  →  CaCo 3  + 2 Na Cl In this reaction, calcium carbonate is obtained as a precipitate. Hence, it is a precipitation reaction.  «« Previous question              Next question »»