Basic Chemistry

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iodic table are observed to follow several other general trends as they progress form left to right and from top to bottom on the periodic table. The first and most obvious trend is the size of the atomic and ionic radii. As the atoms progress from left to right on the table, they become smaller due to added electrons and therefore more negative energy. This negative energy attracts increasingly to the positive energy of the protons drawing them closer together and decreasing the size of the radius. However, as elements progress from top to bottom, they gain radius size. This is due to the fact that more energy levels are added and the outer levels are partially shielded from protons by the lower electron levels. This trend does not apply to ions. The second trend is one in a group of three directly related trends. These three are just the opposite of atomic radii. As elements progress from left to right it increases, but the opposite is true from top to bottom. The first of the three (and the second of all the trends) is ionization energy, or the amount of electron volts needed to remove an electron from an element’s atom. The voltage needed increases from left and right because of the increasing pull between increasing numbers of electrons and increasing protons. It decreases from top to bottom because the more energy levels that exist the farther away the outer levels are from the nucleus the outer electrons are. The third periodic trend is electron affinity or the energy released when a negative ion is formed. It is the opposite of ionization energy in that it measures how easily it attracts other electrons. It is the same, however, in the respect that it also increases from left to right and decreases from top to bottom for the same reasons. The fourth trend, electronegativity measures the tendency of bonded atoms to attract electrons. Linus Pauling invented this trend, based on a scale of zero to four.

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