1. Trends in the Periodic Table

2. Periodic Trends
The arrangement of the periodic table shows trends of properties of the elements
Boiling Point:

3. Atomic Radius Atomic Radius is the size of an atom
Atomic Radius INCREASES as you move down the periodic table
This is because you are adding energy levels each time you move down a level in a group
Atomic Radius DECREASES as you move from left to right
This is because you are adding electrons to the same energy level

4. Atomic Radius

5. Electron Shielding
Shielding electrons are the electrons in the energy levels between the nucleus and the valence electrons.
They are called "shielding" electrons because they "shield" the valence electrons from the force of attraction exerted by the positive charge in the nucleus.
Shielding increases as you move down the periodic table
Adding energy levels
Shielding has no effect as you move across the table from left to right
Not adding energy levels

6. Ionization Energy The energy required to remove an electron
Ionization energy DECREASES as you move down the periodic table
This is due to shielding effect
Ionization energy INCREASES as you move left to right
This is due to the elements increasing atomic charge with no increase in shielding effect
This is mostly due to the atoms wanting to gain an electron to achieve an octet

8. Electronegativity
The desire of an atom in a molecule to attract electrons to itself
Electronegativity DECREASES as you move down the periodic table
This is due to shielding effect
Electronegativity INCREASES as you move left to right
This is because the atoms will want to gain electrons to complete the octet

9. Electronegativity

10. Ionic Size The size of an atom as it becomes an ion
When an atom loses an electron (ionization energy), the atom decreases in size
When an atom gains an electron, the atom increases in size
Both are due to the idea of atomic charge (nucleus is positive, shell is negative)