Periodic

Trends

So how is it arranged?

The elements are placed in specific places based on the way they look and act

The Periodic Table is organized by rows and columns

Rows (left to right)

Columns (up and down)

You've got your periods...

All of the rows go left to

right.

Each of the rows is

considered to be a

different period

Elements in the same

row have the same

number of electron

rings

And you got your groups…

When a column goes from top to bottom, it's called a group.

Elements in the same group have similar chemical properties

Elements in the same group have the same number of valence electrons

Trends

Atomic Radius

Ionization Energy

Electron Affinity/Electronegativity

Reactivity

Metallic Character

Atomic Radius

Size of the atom

Distance from nucleus to the outermost

electron energy level

Decreases from left to right

As you go from left to right, e- are put into

the same energy level, but there are more p+

Increases from top to bottom

As you go down, e- are filled into orbitals

(energy levels) that are farther away from

the nucleus

Atomic Radius

“Effective Nuclear Charge”

Amount of attractive “hold” or Force the

nucleus exerts on electrons

Net positive charge experienced by an electron

Positive Protons attract negative electrons inward

Inner electron energy levels “shield” the outer

electrons

Increases as you move along a period, left

to right

Decreases as you move down a group

Ionization Energy

Energy needed to remove the outermost e-

Elements with a high ionization energy will

not give up their electrons easily

Decreases from top to bottom

As you go down, atomic size is increasing,

therefore there is less attraction and it is easier to

remove an e-

Increases from left to right

As you go from left to right, atomic size is

decreasing, so it is more difficult to remove an e-

Ionization Energy

How do electron configurations explain

why there is a big change in energy at

the red line?

Electron Affinity /

Electronegativity

How good an atom is at pulling in an electron

Increases from left to right

As you go from left to right, atomic size is

decreasing, so the electrons are more

attracted to the nucleus

Decreases from top to bottom (generally)

As you go down, atomic size is increasing,

so there is less attraction of electrons to the

nucleus

Electron Affinity /

Electronegativity

Reactivity

Tendency of an atom to react

Metals – lose e- when they react

Reactivity is based on lowest Ionization Energy

Low ionization energy = high reactivity

Nonmetals – gain e- when they react

Reactivity is based on high electronegativity

High electronegativity = high reactivity

Metallic Character

Increases from top to bottom

Metallic character increases because

ionization energy decreases

Decreases from left to right

Metallic character decreases because

ionization energy decreases

Summary of Periodic

Trends