Notes #2: Periodic Trends Need YOUR PT and blank PT Notes #2: Periodic Trends WCHS Chemistry

Mendeleev Challenge +3+2+1 Main Point - Elements in the same group (vertical column) have similar physical & chemical properties. They follow a pattern as you move down the group!

Trend #1 - Atomic Radii (size) Atoms get LARGER as you go DOWN a group. WHY?? → More energy levels! (to hold more e-s)

TRENDS More energy levels Larger down a group

Trend #1 - Atomic Radii (size) Atoms get LARGER as you go DOWN a group. WHY?? → More energy levels! (to hold more e-s) Atoms get SMALLER as you go ACROSS a period. WHY?? → More protons = nucleus pulls harder on the electrons.

Smaller across a period Larger down a group TRENDS More energy levels Smaller across a period Nucleus pulls harder on e-s Larger down a group

Trend #2 - Valence Electrons electrons found in the outermost energy level They are the only electrons used in bonding! They come in contact with other atoms Group # = # of valence electrons

Smaller across a period Larger down a group EXCEPTION! 8e- TRENDS 2e- 3e- 4e- 5e- 6e- 7e- 2e- More energy levels Smaller across a period Larger down a group Nucleus pulls harder on e-s

Trend #2 - Valence Electrons electrons found in the outermost energy level They are the only electrons used in bonding! They come in contact with other atoms Group # = # of valence electrons EXCEPTION! →Helium (only has 2 e-s total!) K = S = He = O = Ar = Sr = Sn =

Metals form CATIONS (+) Formed when atom GIVES electrons Trend #3 - Ions Metals form CATIONS (+) Formed when atom GIVES electrons Nonmetals form ANIONS (-) Formed when the atom TAKES electrons

Smaller across a period Larger down a group TRENDS NON-METALS take e-s (-) 1e- 8e- 2e- 3e- 4e- 5e- 6e- 7e- METALS give e-s (+) 2e- More energy levels Smaller across a period Larger down a group Nucleus pulls harder on e-s

Trend #4 - Reactivity IA Alkali metals - Extremely Reactive metals! IIA Alkaline Earth metals - reactive Transition metals Rare Earth metals VIIA Halogens - Extremely Reactive nonmetals! VIIIA Noble Gases - Inert - doesn’t react!!!

Transitions from metalic to non-metalic properties TRENDS NON-METALS take e-s (-) 1e- 8e- 2e- 3e- 4e- 5e- 6e- 7e- METALS give e-s (+) 2e- More energy levels Smaller across a period Larger down a group Nucleus pulls harder on e-s Transitions from metalic to non-metalic properties INERT!! Most REACTVE NonMetals REACTIVE Rare on Earth Most REACTIVE Metals

Trend #4 - Reactivity continued Metals become more reactive as you go down the group. Most reactive metal =

Transitions from metalic to non-metalic properties TRENDS NON-METALS take e-s (-) 1e- 8e- 2e- 3e- 4e- 5e- 6e- 7e- METALS give e-s (+) 2e- More energy levels Smaller across a period Larger down a group More reactive down group Nucleus pulls harder on e-s INERT!! Transitions from metalic to non-metalic properties Most REACTVE NonMetals REACTIVE Rare on Earth Most REACTIVE Metals

Trend #4 - Reactivity continued Metals become more reactive as you go down the group. Most reactive metal = Francium!! Nonmetals become more reactive as you go up the group. Most reactive nonmetal =

Transitions from metalic to non-metalic properties TRENDS NON-METALS take e-s (-) 1e- 8e- 2e- 3e- 4e- 5e- 6e- 7e- METALS give e-s (+) 2e- More energy levels Smaller across a period Larger down a group More reactive up group Nucleus pulls harder on e-s More reactive down group INERT!! Transitions from metalic to non-metalic properties Most REACTVE NonMetals REACTIVE Rare on Earth Most REACTIVE Metals

REACTIVITY VIDEOS https://www.youtube.com/watch?v=I8tOtZKpi04