heat flow electron pair molecules atom presence protons neutrons and electrons atomic weights solvent electrophile salicylic acid organic solvents methanol glucose krebs cycle hydrogen activation energy alcohols highest energy synthesis cesium reactants acids and bases Organic reagent dehydration reaction cytosine racemic mixture chemical reactions atoms temperatures sodium equilibrium electrons protons exothermic reaction selectivity covalent bonds catalytic hydrogenation hydrogen peroxide ketone electron acceptor carbons journal article atomic mass cis ammonia chromosomes cells phosphate transition state ethers carbon atoms derivatives local anesthetic substrates reagents chirality catalyst catalysts hydrogen bonds alcohol correlation junior chemistry single step alkyne cell cycles amino acids byproducts acetone nucleophile organic reactions intermediates constituents carbon dioxide molecule aspirin hydrogen gas acyl alkenes proteins concentration diels alder reaction chemistry dehydration pyruvate organic chemistry living organisms dna molecule chemicals room temperature metabolism chemical reaction joules alkene water molecules esters isomer electron density thymine oxidation