Transcript Atomic Mass vs Atomic

Trends in the Periodic Table
Atomic Mass
Atomic Radius
Ionization Energy
Electronegativity
Density
Electron Affinity
Trends in the Periodic Table
Atomic Mass - The represents two things; Mass of an atom in amu (Atomic
Mass Units) , the Molar Mass in grams/mole
Atomic Mass vs Atomic #
120
y = 2.3x - 2.7
100
Atomic Mass
80
60
40
20
0
0
-20
5
10
15
20
25
30
35
40
Atomic Number
• Slope of line is very consistent, therefore predictable
• As Atomic # Increases, Atomic Mass increases linearly
45
Trends in the Periodic Table
Atomic Radius
• In each Row the Radius Decreases
• Moving to Increasing Rows the Radius Increases
Trends in the Periodic Table
Atomic Radius
Trends in the Periodic Table
Why does Radius decrease as electrons are added across a
row?
• Larger nucleus
• More Protons
• More Electrostatic force
Trends in the Periodic Table
Ionization Energy – Energy required to remove an electron from a neutral atom of an
element.
How strong an element holds on to its outer most electron.
Measure in Joules.
A + Energy 
+
A
+
e
Trends in the Periodic Table
Ionization Energy Trend in Periodic Table
• IE increases as you move from Left to Right across Periodic Table
• IE decreased as you move down the Periodic Table
Trends in the Periodic Table
Electronegativity – desire for electrons
• Electronegativity increases as you move from Left to Right across Periodic Table
• EN decreased as you move down the Periodic Table
Trends in the Periodic Table
Density
• Density is high in the middle of the row and low on the ends
• As you move down the Periodic Table the Density of things increases
Trends in the Periodic Table
Electron Affinity – The energy change that occurs when an electron is
acquired by a neutral atom.
Most atoms give away energy when they acquire an electron. Energy
given away is given the sign (-).
A + e-  A- + Energy
Some atoms must be forced to gain an electron by the addition of
Energy.
A + Energy + e-  A-
Trends in the Periodic Table
Electron Affinity – This one is a bit difficult to sort out.
Trends in the Periodic Table
Electron Affinity – Add some lines to see the pattern
Trends in the Periodic Table
Electron Affinity- green lines indicate general trend
• Affinity decreases as you move from left to right.
Trends in the Periodic Table
Summary