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Periodicity. Periodic Trends. Trends we have covered Atomic Mass Atomic Number Valence e- Orbitals by periodic location New ones for Today Atomic radius Ionization energy Reactivity Electronegativity Density and Melting Point. Groups (families). Group 1 – Alkali Metals
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Periodic Trends • Trends we have covered • Atomic Mass • Atomic Number • Valence e- • Orbitals by periodic location • New ones for Today • Atomic radius • Ionization energy • Reactivity • Electronegativity • Density and Melting Point
Groups (families) • Group 1 – Alkali Metals • Group 2 - Alkaline Earth Metals • Group 7 – Halogens • Group 8 – Noble Gases
Atomic Radius • The relative size of an atom • One half the distance between the nuclei of two identical atoms
Atomic Radius • Group trend: size increases as you go down a group • More shells= larger • Period trend: Size generally decreases as you go across a period until you reach the noble gases • More protons= smaller
Ionization Energy • The energy required to overcome the nuclear attraction and remove an electron. Na Na+ + e-
Ionization Energy • Group trend: The energy decreases as you go down a group • it gets easier to remove an electron • Period trend: The energy generally increases as you move across the periodic table • It gets harder to remove an electron
Electronegativity • The tendency for an atom to attract electrons from other elements • Smaller= higher electronegativity and Noble Gases= no electronegativity • Fluorine is the most electronegative
Electronegativity Draw an arrow indicating the general electronegativity trend Increasing electronegativity
Density and Melting Point • Density is highest at the bottom & middle of the PT • Higher density= tighter particles= harder to separate= higher m.p.
Melting Point Trend Hardest to Melt
My fave PT Site Summary Increasing Ionization Energy Increasing Reactivity Increasing Electronegativity Increasing Reactivity Increasing Atomic Radius Highest MP