GET OUT YOUR SCIENCE NOTEBOOKS AND ANSWER THE FOLLOWING: Use a periodic table and your knowledge of the element families to identify each element by name. 1. I am a member of the Carbon family with 14 electrons. 2. I am a member of the Alkaline Earth family and would have 6 energy levels. 3. I am a Transition Metal with 79 protons. 4. I am a member of the Alkali Metal family with 20 neutrons. YOUR TIME REMAINING:

The answers are … 1. I am a member of the Carbon family with 14 electrons. 2. I am a member of the Alkaline Earth family and would have 6 energy levels. 3. I am a Transition metal with 79 protons. 4. I am a member of the Alkali Metal family with 20 neutrons. Silicon Barium Gold Potassium

Periodicity When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties. An important consequence is that the elements with similar chemical and physical properties end up in the same column. Trends on the periodic table govern how elements behave chemically. All elements are unique, but follow these trends….generally.

Ion Charges Group 1 (1A) = All form +1 cations Group 14 (4A) = Form +4 ions Group 15 (5A) = All form ─3 anions Group 16 (6A) = All form ─2 anions Group 17 (7A) = All form ─1 anions Group 18 (8A) = 0 charge, does not gain or lose electrons.

Atomic Radius Atomic radius is ½ the distance between the nuclei of identical atoms that are bonded together. Group Trend – size INCREASES as you move down (added energy levels; electrons farther from nucleus). Period Trend – size DECREASES as you move left to right (more protons and electrons pulling harder on one another). Due to increasing energy levels and shielding by inner electrons. Inner electrons shield the outermost electrons from the nucleus.

Atomic Size Cont.

Check for Understanding: Atomic Radius Which atom has the larger radius? Be or Ba Ca or Br Ba Ca

Check for Understanding: Atomic Radius Rank the following elements by increasing atomic radius: carbon, aluminum, oxygen, potassium. Oxygen, Carbon, Aluminum, Potassium

Ionic Radius Ionic Radius is the relative size of the most common ion of an atom. Group Trend – INCREASE top to bottom due to shielding. Period Trend – In cations, there is a DECREASE left to right across a period. When the Periodic Table switches to anions, there is an increase in size due to the extra level of electrons. However, across a period in the anion section, there is a DECREASE left to right.

Ionic Size/Ionic Radius

Check for Understanding: Ionic Radius Circle the atom in each pair that has the largest ionic radius. B or Al Na or Al S or O O or F Cl or Br Mg or Ca

Electronegativity Electronegativity is a measure of the ability of an atom in a chemical compound to attract electrons when they are chemically combined with atoms of another element. Group Trend – DECREASE as you move down due to increasing number of energy levels. Period Trend – INCREASE from left to right right due to switch from cations to anions. Fluorine has an electronegativity of 4.0, everything below and to the left is lower.

Check for Understanding: Electronegativity Rank the following elements by increasing electronegativity: sulfur, oxygen, fluorine, aluminum, helium helium, aluminum, sulfur, oxygen, fluorine

Electronegativity

Ionization Energy Ionization Energy is the energy required to overcome the attraction of the protons and remove one electron from a neutral atom of an element . The energy required to remove the 1st outermost electron is call the 1st ionization energy.

Ionization Energy Group Trend – ionization energy DECREASES as you move down (electrons further from the pull of the nucleus are easier to remove). Period Trend – ionization energy INCREASES as you move left to right (greater attraction of the nucleus for electrons).

N Ne Cl N or Bi Ba or Ne Cl or Si Examples Which atom has the higher ionization energy? N or Bi Ba or Ne Cl or Si N Ne Cl

Reactivity Metals Non-Metals Group Trend = INCREASES down a group Period Trend = DECREASES from left to right. Non-Metals Group Trend = DECREASES down a group Period Trend = INCREASES from left to right. Exceptions = Group 18 (Noble Gases)