Bounty Ended with 25 reputation awarded by Community♦ occurred Aug 5 '17 at 18:09 5 Unit edited Aug 5 '17 at 4:35 orthocresol♦ 43.4k77 gold badges136136 silver badges267267 bronze badges Some hard data: bond enthalpies (in $$\pu{kJ mol-1}$$) $$\begin{array}{c|c|c|c} \text{Bond} & \text{Enthalpy} & \text{Bond} & \text{Enthalpy} \\ \hline \ce{C-C} & 350 & \ce{Si-Si} & 226\\ \ce{N-N} & 163 & \ce{P-P} & 201\\ \ce{O-O} & 146 & \ce{S-S} & 226\\ \ce{F-F} & 155 & \ce{Cl-Cl} & 240 \\ \end{array}$$ We observe a decrease in bond energy from carbon to nitrogen and from silicon to phosphorus. It is clear and probably have same reason: appearance of lone electron pair of the atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic radii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. The general decrease in energy from carbon to silicon is thanks to increased size of the orbitals of valence level, making them more diffuse with less efficient overlap and longer bond length. The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bonds is easier. Some hard data: bond enthalpies $$\begin{array}{c|c|c|c} \text{Bond} & \text{Enthalpy} & \text{Bond} & \text{Enthalpy} \\ \hline \ce{C-C} & 350 & \ce{Si-Si} & 226\\ \ce{N-N} & 163 & \ce{P-P} & 201\\ \ce{O-O} & 146 & \ce{S-S} & 226\\ \ce{F-F} & 155 & \ce{Cl-Cl} & 240 \\ \end{array}$$ We observe a decrease in bond energy from carbon to nitrogen and from silicon to phosphorus. It is clear and probably have same reason: appearance of lone electron pair of the atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic radii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. The general decrease in energy from carbon to silicon is thanks to increased size of the orbitals of valence level, making them more diffuse with less efficient overlap and longer bond length. The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bonds is easier. Some hard data: bond enthalpies (in $$\pu{kJ mol-1}$$) $$\begin{array}{c|c|c|c} \text{Bond} & \text{Enthalpy} & \text{Bond} & \text{Enthalpy} \\ \hline \ce{C-C} & 350 & \ce{Si-Si} & 226\\ \ce{N-N} & 163 & \ce{P-P} & 201\\ \ce{O-O} & 146 & \ce{S-S} & 226\\ \ce{F-F} & 155 & \ce{Cl-Cl} & 240 \\ \end{array}$$ We observe a decrease in bond energy from carbon to nitrogen and from silicon to phosphorus. It is clear and probably have same reason: appearance of lone electron pair of the atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic radii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. The general decrease in energy from carbon to silicon is thanks to increased size of the orbitals of valence level, making them more diffuse with less efficient overlap and longer bond length. The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bonds is easier. 4 Jax tidying, few other text tweaks edited Aug 4 '17 at 19:30 hBy2Py 14.8k33 gold badges5454 silver badges9393 bronze badges Some hard data: bond enthalpies $$\begin{array}{c|c|c|c} Bond & Enthalpy &Bond & Enthalpy \\ \hline C-C & 350 & Si-Si & 226\\ N-N & 163 & P-P & 201\\ O-O & 146 & S-S & 226\\ F-F & 155 & Cl-Cl & 240 \\ \end{array}$$$$\begin{array}{c|c|c|c} \text{Bond} & \text{Enthalpy} & \text{Bond} & \text{Enthalpy} \\ \hline \ce{C-C} & 350 & \ce{Si-Si} & 226\\ \ce{N-N} & 163 & \ce{P-P} & 201\\ \ce{O-O} & 146 & \ce{S-S} & 226\\ \ce{F-F} & 155 & \ce{Cl-Cl} & 240 \\ \end{array}$$ We observe fala decrease in bond energy from carbon to nitrogen and from silicon to arsenicumphosphorus. It is clear and probably have same reason: appearance of lone electron pair otheof the atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic readiiradii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. The general fall downdecrease in energy from carbon to silicon is thanks to increased size of the orbitals of valentvalence level, making them more diffuse with less efficient overlap and longer bond length. The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bondbonds is easier. Some hard data: bond enthalpies $$\begin{array}{c|c|c|c} Bond & Enthalpy &Bond & Enthalpy \\ \hline C-C & 350 & Si-Si & 226\\ N-N & 163 & P-P & 201\\ O-O & 146 & S-S & 226\\ F-F & 155 & Cl-Cl & 240 \\ \end{array}$$ We observe fal in bond energy from carbon to nitrogen and from silicon to arsenicum. It is clear and probably have same reason: appearance of lone electron pair othe atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic readii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. The general fall down in energy from carbon to silicon is thanks to increased size of the orbitals of valent level, making them more diffuse with less efficient overlap and longer bond length. The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bond is easier. Some hard data: bond enthalpies $$\begin{array}{c|c|c|c} \text{Bond} & \text{Enthalpy} & \text{Bond} & \text{Enthalpy} \\ \hline \ce{C-C} & 350 & \ce{Si-Si} & 226\\ \ce{N-N} & 163 & \ce{P-P} & 201\\ \ce{O-O} & 146 & \ce{S-S} & 226\\ \ce{F-F} & 155 & \ce{Cl-Cl} & 240 \\ \end{array}$$ We observe a decrease in bond energy from carbon to nitrogen and from silicon to phosphorus. It is clear and probably have same reason: appearance of lone electron pair of the atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic radii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. The general decrease in energy from carbon to silicon is thanks to increased size of the orbitals of valence level, making them more diffuse with less efficient overlap and longer bond length. The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bonds is easier. 3 deleted 191 characters in body edited Aug 4 '17 at 19:02 permeakra 18.8k11 gold badge4141 silver badges8787 bronze badges Some hard data: bond enthalpies $$\begin{array}{c|c|c|c} Bond & Enthalpy &Bond & Enthalpy \\ \hline C-C & 350 & Si-Si & 226\\ N-N & 163 & As-As & 146\\ O-O & 146 & S-S & 226\\ F-F & 155 & Cl-Cl & 240 \\ \end{array}$$$$\begin{array}{c|c|c|c} Bond & Enthalpy &Bond & Enthalpy \\ \hline C-C & 350 & Si-Si & 226\\ N-N & 163 & P-P & 201\\ O-O & 146 & S-S & 226\\ F-F & 155 & Cl-Cl & 240 \\ \end{array}$$ We observe fal in bond energy from carbon to nitrogen and from silicon to arsenicum. It is clear and probably have same reason: appearance of lone electron pair othe atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic readii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. It seems, thatThe general fall down in case of As this effect is overshadowed by the fact, that lone pairenergy from carbon to silicon is located on the S-orbital, isnteadthanks to increased size of hybridized $$sp^3$$the orbitals of valent level, making them more diffuse with less efficient overlap and thus they repulse strongerlonger bond length.   The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bond is easier. Some hard data: bond enthalpies $$\begin{array}{c|c|c|c} Bond & Enthalpy &Bond & Enthalpy \\ \hline C-C & 350 & Si-Si & 226\\ N-N & 163 & As-As & 146\\ O-O & 146 & S-S & 226\\ F-F & 155 & Cl-Cl & 240 \\ \end{array}$$ We observe fal in bond energy from carbon to nitrogen and from silicon to arsenicum. It is clear and probably have same reason: appearance of lone electron pair othe atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic readii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. It seems, that in case of As this effect is overshadowed by the fact, that lone pair is located on the S-orbital, isntead of hybridized $$sp^3$$ orbitals, and thus they repulse stronger.   The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bond is easier. Some hard data: bond enthalpies $$\begin{array}{c|c|c|c} Bond & Enthalpy &Bond & Enthalpy \\ \hline C-C & 350 & Si-Si & 226\\ N-N & 163 & P-P & 201\\ O-O & 146 & S-S & 226\\ F-F & 155 & Cl-Cl & 240 \\ \end{array}$$ We observe fal in bond energy from carbon to nitrogen and from silicon to arsenicum. It is clear and probably have same reason: appearance of lone electron pair othe atom. There is a repulsion between lone pairs, that is in partially compensated by stronger bonds formed by smaller atoms (the atomic readii falls down to the end of the row). When moving from second to third row, this repulsion is reduced thanks to larger size of atoms of the elements of the third row. The general fall down in energy from carbon to silicon is thanks to increased size of the orbitals of valent level, making them more diffuse with less efficient overlap and longer bond length. The stability of esters vs thioesters is ruled by different reasons. Sulfur is not as electronegative as oxygen, but when you consider an anion, sulfur anions have larger radius and are less prone to grabbing first positive charge they find. So sulfur anions are more stable intermediates (kinetically), and thus polar dissociation of thioester bond is easier. 2 added 364 characters in body edited Aug 4 '17 at 14:40 permeakra 18.8k11 gold badge4141 silver badges8787 bronze badges 1 answered Aug 4 '17 at 14:35 permeakra 18.8k11 gold badge4141 silver badges8787 bronze badges