ch. 11 – periodicity: patterns in periodic table explaining chemical and physical properties
TRANSCRIPT
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
? ?
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?