1/17/2024 0 Comments Reactivity trend in periodic tableThis is best illustrated with the halides: basicity, like electronegativity, increases as we move up the column.Ĭonversely, acidity in the haloacids increases as we move down the column. When moving vertically within a given column of the periodic table, we again observe a clear periodic trend in acidity. Once again, a more reactive (stronger) conjugate base means a less reactive (weaker) conjugate acid. The nitrogen lone pair, therefore, is more likely to break away and form a new bond to a proton - it is, in other words, more basic. Oxygen, as the more electronegative element, holds more tightly to its lone pair than the nitrogen. We can use the same set of ideas to explain the difference in basicity between water and ammonia.īy looking at the pK avalues for the appropriate conjugate acids, we know that ammonia is more basic than water. Thus, the ethoxide anion is the most stable (lowest energy, least basic) of the three conjugate bases, and the ethyl anion is the least stable (highest energy, most basic). The more electronegative an atom, the better it is able to bear a negative charge. Remember the periodic trend in electronegativity: it also increases as we move from left to right along a row, meaning that oxygen is the most electronegative of the three, and carbon the least. In the ethyl anion, the negative charge is borne by carbon, while in the methylamine anion and ethoxide anion the charges are located on a nitrogen and an oxygen, respectively. Look at where the negative charge ends up in each conjugate base. The key to understanding this trend is to consider the hypothetical conjugate base in each case : the more stable (weaker) the conjugate base, the stronger the acid. We can see a clear trend in acidity as we move from left to right along the second row of the periodic table from carbon to nitrogen to oxygen. We’ll use as our first models the simple organic compounds ethane, methylamine, and ethanol, but the concepts apply equally to more complex biomolecules, such as the side chains of alanine, lysine, and serine. \)įirst, we will focus on individual atoms, and think about trends associated with the position of an element on the periodic table.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |