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  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 Make a prediction AtomicradiusAtomicradius Atomic Number

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

Atomic Radius

Ionization Energy  Make a prediction IonizationEnergyIonizationEnergy Atomic Number

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

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Ionization energy

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

Summary Increasing Atomic Radius Increasing Ionization Energy Increasing Electronegativity Increasing Reactivity Highest MP My fave PT Site