1. Chemistry
Chapter 6/7
Notes #3

2. Periodic Trends
Many elemental properties change in a predictable way (trend) as you move across the periodic table in periods, or down the periodic table in families/groups
4 Examples
Atomic Radius
Ionic Radius
Ionization Energy
Electro negativity

3. Atomic Radius
Going left to right on the periodic table atomic radius decreases
Due to increased nuclear positive charge, pulling electrons closer
Going down the periodic table (in columns) atomic radius increases
Due to increasing p.e.l.’s
E- are further from nucleus – hence less pull on them
Shielding

4. Atomic Radius

5. Ionic Radius
Ion – Atom that has lost or gained electrons and has an overall charge
Loss of electrons = positive charge
Gain electrons = negative charge
Loss of e- : gets smaller than original atom (empty outer energy level – electrons get pulled closer to nucleus)
Gain of electrons: Radius gets bigger – increases electrostatic repulsion (likes repel)

6. Ionic Radius Moving down the columns Moving left to right
Ionic radius generally increases
Same reason that atomic radius increases
Moving left to right
Generally decreases.
First along the metals
Big jump in size when you hit nonmetals
Then, they decrease again

7. Ionic Radius

8. Ionic radius increases
Ionic radius decreases
Ionic radius increases

9. Ionization Energy
The energy needed to overcome the attraction between the + charge in the nucleus and the – charge of the electron in order for an electron to be removed from the outer energy level of a neutral atom
High ionization energy: atom has strong hold on its e-
Low ionization energy – atom loses e- more easily
All follows the octet rule!
Moving down the columns it decreases (atoms are larger – the electrons are farther from the nucleus – so they are easier to remove)
Moving left to right – atoms have a stronger hold on their electrons

10. Ionization energy decreases
Ionization energy increases as you move to the right
Ionization energy decreases

11. Electro negativity
The ability of an atom to attract electrons in a chemical bond
Moving left to right – it increases
Moving down the columns, it decreases
Lowest electro negativities are found at the lower left of the table
F = most electronegative element

12. Electronegativity decreases
Electronegativity increases as you move to the right
Electronegativity decreases