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

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

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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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 generalelectronegativity 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

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Highest MP

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