PERIODIC TABLE TRENDS & REACTIVITY Phenomenon: Three periodic trends (atomic radius, ionization energy, and electronegativity) help chemists determine an element’s reactivity in creating compounds.

Within a Group, elements have the same number of valence electrons but as you go down a group, the number of shells increase. As the number Of shells increase, the valence electrons are moved closer away from the nucleus. Thus, it will require less energy (lower Ionization energy) to remove an electron from the outermost shell and It will also be more difficult To attract electrons (low electronegativity)

Within a period, elements have the same number Of Shells, But Increase in the number Valence electrons as you travel across a period. As the number of Protons and valence electrons Increase, The attraction increases which pulls the outermost shell closer to the nucleus (Opposites Attract). As the electrons move closer to the nucleus, It will require more energy to remove them (High ionization energy) and It will be easier for the atom to attract more electrons (High electronegativity).

REACTIVITY OF Metals: As you go from right to left within a period, the amount of valence electrons a Metal has to give away decreases, so It will become more readily available to react. As you go down a group, the valence electrons move farther away from the nucleus (more shells) which make them easier to be given/taken away. Francium is the most reactive metal! reactivity of non-metals: As you go left to right within a period, the atom is getting a closer to obtaining a full valence shell, so the more readily it will react to receive those electrons. As you go up a group the amount of shells an atom has decreases which pulls the valence electrons in the outermost shell closer to the nucleus and increases an atom’s ability to attract more electrons To The protons in its nucleus. Fluorine is the most reactive non-metal!

Let’s Practice: Which metal is more reactive?

Let’s Practice: Which metal is more reactive?

Let’s Practice: Which non-metal is more reactive?

Let’s Practice: Which non-metal is more reactive?