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Have Students come up with a trend in reactivity for the halogens (group 17).ġ. It will be more reactive then all of them (except chlorine because it is the same).Ĥ. Pour the chloride (bleach) into each of the solutions. They should be making a prediction of each event and then explaining their prediction.ģ. Tell them that reactivity describes how reactive the element is.Ģ. Explain what would happen once chloride (bleach) was poured into one of the vials if the chloride was more reactive than the element (chlorine, bromine, iodine). Have three vials of aqueous NaCl, NaBr, and NaI ready.ġ.We will be comparing six different elements today in class Lithium, Sodium, Magnesium, Chlorine, Bromine, and Iodine and observing how they react differently.Just as the students had to compare different elements to create their own periodic tables, scientists had to compare the elements to place them in groups.We will be looking at the general trend of how elements react across the periodic table and what causes these differences in reactivity.Introduce topic of Reactivity in the unit of Periodic Trends.Going to have to relate many of these ideas today to understand what is going on.Learned that the elements are arranged in the Periodic table in a way that helps to relate the characteristics of those elements.Learned that atoms are different because of their number of protons, neutrons, electrons and different in the way that the electrons are positioned around the nucleus.Learned about how each element is different from each other and thus each atom that makes up the elements is different from one another.

Know that elements are composed of their specific atoms.

Remind them of what they already know about atoms and elements.

Welcome students into class and tell them they will begin a new unit.

Before students enter classroom make sure that materials are ready and that the necessary safety equipment is nearby.

Non-metals that are up and to the right are closer to the noble gases and do a better job of attracting electrons to their nucleus because they don’t have as many energy levels, and therefore their electrons feel less shielding. For non-metals the trend is that reactivity increases up and to the right. Metals that are down and to the left are closer to the noble gases and have electrons that are easier to remove. The trend for metals is increasing reactivity down and to the left. This also accounts for trends of reactivity. Electrons in higher energy levels are further away from the nucleus and do not feel as much attraction to the nucleus as electrons in lower energy levels. Also as you move down the periodic table the dominant factor is the number of energy levels. Metals react to lose electrons while non-metals react to gain electrons due to their position on the periodic table that corresponds to their valence electrons. This simple idea leads to the reactivity trends we observe. Depending on the number of electrons all ready in their valence shell it may be easier to either gain or lose electrons. Elements all want to be more stable, and the easiest way to accomplish this goal is to either gain or lose electrons to fill their valence shell orbital.

Reactivity is a periodic trend that is ultimately related to valence electrons and the process of gaining and losing electrons to become more stable. One major observable periodic trend is reactivity. The development of the periodic table (which occurred well before atomic substructure was understood) was a major advance, as its patterns suggested and led to the identification of additional elements with particular properties. (Most of this text came from the National Science Education Standards Framework draft, pages 89-91). The substructure of atoms determines how they combine and rearrange to form all of the world’s substances. Today the table’s patterns are now recognized as related to the atom’s outermost electron patterns, which play an important role in explaining chemical reactivity and bond formation, and the periodic table continues to be a useful way to organize this information. Some of these patterns include trends in oxidation numbers, atomic radii, and elemental group/families, just to name a few. As the table is constructed in a logical fashion based off certain properties many other patterns begin to arise, all of which correlate with atomic structure that explains chemical phenomena and interactions among different elements.

The periodic table is constructed around the elements and their different characteristics.