The formation of chemical compounds takes place as a result of combination of atoms of various elements.
Explain how ionization enthalpy (I.E) and electron gain enthalpy (E.G.E) determine whether atoms of elements will combine to form ionic compounds.

The formation of chemical compounds takes place as a result of combination of atoms of various elements. The dipole moment of NH_3 is 0.49 D and that of BF_3 is zero. From the above values predict molecular structure of NH_3 and BF_3 .

The energy released during the addition of an electron to an isolated neutral atom is called electron gain enthalpy. a) Explain how electron gain enthalpy differ from electronegativity. b) The second ionisation enthalpy of an element is always greater than the first ionisation enthalpy. Give reason.

Among the elements B , Al , C and Si . a. Which has the highest first ionization enthalpy? b. Which has most negative electron gain enthalpy? c. Which has the largest atomic radius? d. Which has the most metallic character?

The element Cu with atomic number 29 undergoes chemical reaction to form an ion with oxidation number +2. a) Write down the subshell electronic configuration of this ion? b) Can this element show variable valency? Why? c) Write down the chemical formula of one compound formed when this elemrnt reacts with chlorine (Cl_17)

11,17,10 are the atomic number of elements X,Y and Z: Write the molecular formulac of the compound formed when any two of the above elements are combined.

A quantitative measure of the tendency of an element to lose electron is given by its ionisation enthalpy (I.E.). I.E. increases from left to right in a period of the periodic table. However, in second period, the I.E of oxygen is less than that of nitrogen. Why?

The combination of elements of form compounds is governed by the laws of chemical combination. Hydrogen combines with oxygen to form compounds, namely water and hydroge peroxide. 28 g of nitrogen is mixed with 12 g of hydrogen to form ammonia as per the reaction, N_2 + 3H_2 rarr 2NH_3 . Which is the 'limiting reagent' in this reaction? [Atomic masses: N = 14, H = 1]