Periodic Trends
http://www.youtube.com/watch?v=Q
SZ-3wScePM
6.1 Organizing the Elements
The Periodic Table
6.3 Periodic Trends


Properties that change in a
predictable pattern as you move
through the periodic table.
XOOXOOXO
6.3 Periodic Trends

Electron Shielding


Atomic Radius


The size of the atom
Ionization energy


The ability of the core electrons to shield
the outer electrons from the nucleus
The energy needed to remove an
electron
Electronegativity

The tendency of an atom to attract an
electron while in a bond
6.3 Periodic Trends
Electron Shielding
6.3 Periodic Trends
Electron Shielding
6.3 Periodic Trends
Electron Shielding
6.3 Periodic Trends
Atomic Radius


The distance from the center of the
nucleus to the outermost electron
Increases going down a group



Electron Shielding increases
Outer electrons are able to move
farther from the nucleus
Decreases going across a period


Electrons shielding remains constant
The nucleus pulls the electrons closer.
6.3 Periodic Trends
Atomic Radius
6.3 Periodic Trends
Ionic Size

Size of an ion




Cations (positive ions) are smaller than
the atom they came from
Anion (negative ions) are larger than
the atom they came from
Increases down a group
Positive ions decrease and then
negative ions decrease across a
period
6.3 Periodic Trends
Ionic Size
6.3 Periodic Trends
Ionization Energy


The energy needed to remove an
electron from an atom to give a
charge of positive one
Increases across a period


Atomic size decreases, outer electrons
are harder to pull off
Decreases down a group

Atomic size increases, outer electrons
are easier to pull off
6.3 Periodic Trends
Ionization Energy
6.3 Periodic Trends
Electronegativity


The ability of an atom to attract an
electron while it is in a bond.
Increases across a period


Decreases down a group


Atomic size decreases, easier for the
nucleus to attract other electrons
Atomic size increases, harder for the
nucleus to attract other electrons
Noble gases do not have
electronegativities because they are
typically not involved in bonds
6.3 Periodic Trends
Electronegativity
6.3 Periodic Trends




How many electrons are in a
Sodium Atom?

11
How many energy levels are
there in a Na atom?

3
How many electrons go in
levels 1,2,3 and 4?

2,8,18,32

2,8,1
In our Na atom how many
electrons will go in each level?