1. Chapter 6: Periodic Table Trends
Wasilla High School

2. Periodic Law
Dmitri Mendeleev created the first real periodic table by arranging the elements in order or increasing atomic mass
Was so accurate, he was able to predict the existence of elements not yet discovered
Modern periodic table – elements are organized by increasing atomic number

3. Mendeleev’s Periodic Table

4. Periodic Trend #1: Atomic Size
Atomic size increases from top to bottom and decreases from left to right

5. Periodic Trend #2: Ionization Energy
The energy required to remove an electron from an atom
You can have a first, second and third ionization energy
Decreases as you move down a group, increases as you move across a period from left to right

6. Ionization Energy is Related To Valence Electrons
Group IA elements have one valence electron
Low 1st Ionization Energy
Extremely High 2nd Ionization Energy
Group IIA elements have two valence electrons
Low 1st and 2nd Ionization Energy
Extremely High 3rd Ionization Energy
Nonmetals ALWAYS have high ionization energies
They want to GAIN electrons not LOSE

7. Periodic Trend #3: Electronegativity
Electronegativity is the ability of an atom to attract electrons
Values decrease from top to bottom and increase from left to right