Trends in the Periodic Table

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

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

Atomic Radius

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

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

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

Electronegativity

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)