Question

1. The distance between chlorine and sodium in Naal is 2.82 A, but their atomic radi are 0.99 and 1.54 A, respectively Explain the discrepancy between the sum of the radi and the distance. 2. The element Setonium, St, is the next, undiscovered noble gas in the periodic table based on the Pauli's principle that a maximum of 3 electrons can occupy an orbital. Give the electronic configuration of the valence shell of St. 3. Oxidation can be defined as either (0) the combination of an atom or molecule with oxygen, for example the oxidation of a hydrocarbon to water and carbon dioxide or the oxidation of iron to iron oxide, or, () the shift the charge of a species toward more positive values by loss of electrons to an atom or molecule, for example the reaction of Fe with carbon, 2FeO reaction C is oxidized by Fe while the metal ion is reduced. Thus, Fe is an oxidant or oxidation reagent. Consider the species I, O, Zn, Sn", and K. Choose which one(s) you would expect to be a good oxidant. Justify your answer.

Answer 1

1. Sodium chloride (NaCl) is an ionic compound which is formed by the electrostatic attraction between sodium ions and chloride ions. Sodium atom completely transfers an its valency electron to the chlorine atom resulting in the formation of positively charged sodium ion and negatively charged chloride ion. The force of attraction between these positive and negative charges held these at fixed positions and we call this electrostatic interaction as ionic bond. Unlike in the covalent bond, an ionic bond does not require a direct physical contact of the two atoms to form bond. It is the attractive force we call a bond and not a physical contact. The magnitude of this attraction is directly proportional to the charge on the atoms and bond strength. As the charge on atoms increases, the attaction between then increases resulting in the decreased inter nuclear distance.

There are two points to be considered here.

1. There is an ionic bond between Na and Cl - the internuclear distance need to be less than sum of atomic radii.

2. Na and Cl both have charge of magnitude one only - results in lesser bond strength and more internuclear distance.

Thus the sum of atomic radii of Na and Cl

0.99 + 1.59 = 1.58$\AA$ is smaller than inter nuclear distance of 2.82$\AA$