Why cu is not stable in aqueous solution

The shielding effect of f-orbitals in very poor due to their diffused shape. It results in the stronger force of nuclear attraction of the 4f electrons and the outer electrons causing decrease in size. Consequences of lanthanoid contraction: i Similarly in the properties of elements of second and third transition series e.

This resemblance is due to the similarity in size due to the presence of lanthanoids in berween. The important characteristics of transition metals are: i All transition elements are metallic in nature, e. The presence of partially filled d-orbitaIs in the electronic configuration of atomic and ionic species of these elements is responsible for the characteristic properties of transition elements.

They are called transition elements because of their position in the periodic table. These elements lie in the middle of periodic table between s and p-blocks i. A transition element may be defined as a element whose atom or at least one of its simple ions contain partially filled d-orbitals, e. The general characteristic electronic configuration may be written as n — 1 d 1—10 ns 1—2.

The elements of group 12 i. One of the main characteristic of a transition element is that it can show large variety of oxidation states in its compounds. It is due to its characteristic electronic configuration i. The stability of oxidation state depends mainly on electronic configuration and also on the nature of other combining atom.

The elements which show largest number of oxidation states occur in or near the middle of series i. The lesser number of oxidation states at extreme ends arise from either too few electrons to loose or share e. Sc and Ti or too many d electrons hence fewer orbitals available in which to share electrons with others for higher elements at upper end of first transition series i. Thus electronic configuration, to large extent, the existence and stability of oxidation states.

The other factors which determine stability of oxidation state are: i Enthalpy of atomisation ii Ionisation energy iii Enthalpy of solvation iv E. Interstitial compounds are those which are formed when small atoms like H, C, N, B etc.

They are generally non-stoichiometric and neither typically ionic nor covalent. Most of transition metals form interstitial compounds with small non-metal atoms such as hydrogen, boron, carbon and nitrogen. These small atoms enter into the void sites between the packed atoms of crystalline transition metals and form chemical bonds with transition metals.

For Example, steel and cast iron become hard by forming interstitial compound with carbon. The existence of vacant n — 1 d orbitals in transition elements and their ability to make bonds with trapped small atoms in the main cause of interstitial compound formation.

Other examples are : VH 0. Some borides of transition elements approach diamond in hardness. The melting points and solubility in water of amino acids are generally higher than that of the corresponding halo acids.

Q1 Silver atom has completely filled d orbitals 4d10 in its ground state. How can you say that it is a transition Q3 Which of the 3d series of the transition metals exhibits the largest number of oxidation states and why?

What is possibly the reason for this? Hint: consider Q5 How would you account for the irregular variation of ionization enthalpies first and second in the first series Q6 Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only? Q10 Actinoid contraction is greater from element to element than lanthanoid contraction.

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Q:- The melting points and solubility in water of amino acids are generally higher than that of the corresponding halo acids.