Ch. 11 – Periodicity:Patterns in Periodic Table

Explaining Chemical and Physical Properties

ReviewWhat Patterns do You Already Know?

• Atomic number• Type of Atoms• Electron Configurations• Alkali Metals• Halogens• Noble Gases

Review: Atomic Numbers

Review: Type of Atoms

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Review: Electron Configurations

sp

d

f

+1

s blockp block

+2 +3 +4 -3 -2 -1 0Common Charges

Other Physical and Chemical Patterns

• Melting Points• Boiling Points• Reactivity– Type of Bonds– Number of Bonds

• Solubility• Density

These Patterns of Properties on the Periodic Table Affect Geology…

Patterns Affect Health…

Two New Important PatternsThat affect all Chemical and Physical Characteristics

Patterns in Size of Atoms

Patterns in Electron Holding Ability

3 Reasons for Patterns

• Valence Shell• Protons per Shell• Shielding

1. Valence Shell Occupied

• More Valence Shells– Farther from nucleus = atom can be larger

• This pattern can be seen as you look…

– Down a Column(size increases at each new row)

2. Protons in Nucleus per Shell• For atoms occupying a given shell (say the second shell…

– Lithium has 3 protons (3+) can hold electrons in the second shell “OK”

– Neon has 10 protons (10+), and has much more attractive force to hold electrons, can hold electrons in the second shell “STRONGLY”• Strong attraction “skrunches” the size of the atom

• This is called “electron affinity” and the atoms on the right side of the periodic table “skrunch” the size

– Across the Row(size “skrunches” as you move to the right from group to group)

3. Shielding

• When there are many electrons in the inner shells– Interfere with ability of protons to attract

electrons

– This pattern can be seen as you look

• Down a Column

Practice• Which atoms are largest or smallest?• Which atoms are least able to hold valence electrons?

• Consider– Shell– Electron Affinity– Shielding

• Rank these atoms– Potassium– Fluorine– Carbon

Quiz

1. What are the two new patterns on the Periodic Table that you have to learn about?

2. What are the three main reasons for these patterns?