Question

Please explain each of the questions, thanks.

1. Describle the correlation between bond energy and bond length for a series of single bonds.

2. Describle, with appropriate explanantions, the key factors which affect the magnitude of the lattice energy of an ionic substance.

3. Explain why hydrogen is placed in Group IA even though it really belongs in a group by itself.

4. Explain when and why chemists make use of the concept of hybridization.

5. Explain why the first member of each period (row) in the periodic table differs so greatly from the rest of the elements in the same period.

6. Explain how the elements in Group IVA differ.

7. Explain why the trend in electron affinity increases in general as you move from left to right across a period (row) of the periodic table.

Answer 1

1. Bond energy is inversely proporational to bond length. Thus, shorter a bond be higher would be the bond energy. Bond energy is energy required to break a bond.

Say for C-C a single bond when compared to a C=C and a C C triple bond, the bond energy would increase in the order C-C single < C=C double < C C triple bond. the increased s-character in from C-C single bond to triple bond makes the bond much stronger and more diffficult to break.

2. Lattice energy which is energy that is released when two ions of opposite charges are combined together to form a ionic bond. As expected stronger bonds would be for ions which are smaller in size and greater in charge as the attraction would be maximum between the opposite charges. thus higher lattice energies.

3. Hdrogen has similar electronic configuration as Group-IA metals, al of which have 1 electron in their outer s-orbital. thus it is placed above group-IA series.

4. Hybridization is used to explain the equal strengths of bonds formed when atoms come together. Say for example C has 2s2 2p2 electronic configuration in its valence shell. Technically s and p orbital should have different energies. However, all the C-H bonds formed in a tetrahedral CH4 are of same strength. this led to the idea of mixing atomic orbital of different energies to generate a new set of hybrid orbitals of equal energies, which is termed as hybridization.

5. First member of each period in the periodic table have fewer shells as compared to the rest of the elements in the period. They have limited number of electrons and cannot expand its octet like others, thus bonding is limited in these elements, as oppsoed to other elements on the same period.

6. Group IVA stays in the middle of the periodic table of elements, they have the tendency to loose electrons at the same time can also gain electrons. Thus they have varied oxidation states. They form strong covalent bonds with non-metals. They have properties between metals and non-metals in the periodic table.

7. Electron affinity is the ability to take electrons by the elements. The ability depends upon size thus smaller the size greater would the the internuclear attraction and higher would be the tendency to take electrons by the electrons. Internuclear attraction is the attraction between the valence shell electrons and the positively charged nucleus. As the number of electrons increases in the outer shell, the attraction between the nucleus and proton in the nucleus increases, the elements tends to acheive the octet state, which is the most stable state. thus the electron affinity increases going from left to right in the periodic table.