+ Organization of the Periodic Table Periodic Trends

+ Organization The periodic table is organized so that elements are grouped together that have similar properties and characteristics. This allows us to predict how an element will react based on its position on the chart.

+ Atomic Radius how large the atom is from the center of the nucleus to the outer valence shell. Increases down and to the left. Why? As protons are added moving across the table, the positive charge is increased which pulls in the electrons in the outer shell closer. This decreases the radius. As we move down a group on the table the radius increases because electrons begin to fill valence shells that are further away from the nucleus.

+ Ionization Energy energy required to remove an electron from a neutral atom. Increases up and to the right. Why? More energy is required to remove an electron as the valence shell becomes fuller. If the atom doesn’t have as much to lose it will be more willing to give up one or two electrons. As we move down the table more electron shells cover the nucleus shielding it from knowing what it has to lose.

+ Electronegativity force of attraction of an atom to electrons/ ability to attract electrons. Increases up and to the right. Why? As we move down, electrons are farther from the nucleus (attractive/ positive force) because more electron shells are being added so attraction is higher at the top of the group. As we move across the table (left to right) the atomic radius decreases because the number of protons increases, pulling in tighter the electron shells increasing the attractive force.

+ Metallic vs. Non-metallic elements Metallic character relates to the ability of an element to lose electrons Non-metallic character relates to the ability of an element to accept electrons. Elements increase metallic character as we move to the left on the periodic table.

+ Valence Electrons As energy levels increase, number of valence electrons stay the same for each group Example: Alkali Metals (Group 1) has 1 electron in the outer shell Alkali Earth Metals (Group 2) have 2 electrons in outer shell All halogens (group 17) have 7 electrons in their outer shell Noble Gases (Group 18) have a full 8 electrons in their outer shell

+ Periodic Trends

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