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Periodic Table and Periodicity

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Presentation on theme: "Periodic Table and Periodicity"— Presentation transcript:

1 Periodic Table and Periodicity

2 Dmitri Mendeleev “The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.”

3 I. History A. Dimitri Mendeleev, 1869 B. Moseley, 1914
periodic law: The chemical and physical properties of the elements are periodic functions of their atomic numbers; When the elements are arranged in order of increasing atomic number, there is a periodic repetition of their properties.

4 II. Structure/Organization
A. Periodic table Periods Groups or families Valence electrons - Representative elements B. Metals - Alkali metals - Alkaline earth metals - Transition metals - Inner transition metals C. Nonmetals - Halogens - Noble gases D. Semimetals/metalloids

5 Compare properties of metals and nonmetals

6 Periodicity in properties
A. Ionization energy

7 Ionization Potential/Energy
IE: Energy required to remove e- Higher the IE: more difficult to remove e- Across Period IE INCREASES* as the number of protons increases * with each subshell Why? (effective nuclear charge) Down Group IE DECREASES as the number of shells increases Why? (shielding, effective nuclear charge)

8 B. Electronegativity

9 Electronegativity The ability to attract e- Across Period EN INCREASES
Because nuclear charge (# p+) increases Down Group EN DECREASES Because more shells (n), more shielding, e- further away from nucleus

10 C. Atomic/ionic radius

11 Atomic Radius Across Period Atomic size DECREASES!
Because nuclear charge (# p+) increases, as e- are added to same shell (n), pulls e- in tighter Down Group Atomic size INCREASES Because more n (shells), more shielding, e- further away from nucleus

12 Ionic

13 Ionic Radius Ion Charged atom Cation
Positive (+) ion (neutral atom looses e-) Anion Negative (-) ion (neutral atom gains e-) Isoelectronic Same electron structure

14 Ionic Radius Across Period IR DECREASES* (why?)
* with jump up in metalloids! Down Group IR INCREASES Compare to neutral atom Valence e- are the outermost e- of an atom

15 D. Metallic character/nonmetallic character
Nonmetallic character increases Metallic Character Increases

16 Metallic Properties Across Period Metallic Properties DECREASES Down Group Metallic Properties INCREASES

17 Summary of Periodic Table Trends
Moving Left --> Right Atomic Radius Decreases Ionization Energy Increases Electronegativity Increases Metallic character decreases Moving Top --> Bottom Atomic Radius Increases Ionization Energy Decreases Electronegativity Decreases Metallic character increases

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