Periodic Trends

Electron Shielding New Vocabulary The reduction of the attraction between a positively charged nucleus and its outermost electrons due to the cancellation of a portion of the positive charge by the innermost electrons

Atomic Radii Down a Group Atomic radii generally increase as you move down a group This trend is caused by the addition of an energy level from one row to the next

Atomic Radii Across a Period Atomic radii generally decrease as you move across a period This trend is caused by the increasing positive charge of the nucleus as protons are added

Atomic Radii Trend Visual

Ionization Energy Review Vocabulary The amount of energy needed to remove an outer electron from an atom in its ground state and in gas phase

Ionization Energy Down a Group This trend is the opposite of atomic radii. The closer or more tightly bound an electron is to its nucleus, the harder it will be to remove As you move down a group, ionization energy decreases because the electrons are further from their nucleus

Ionization Energy Across a Period This trend is also the opposite of atomic radii As you move across a period, ionization energy increases because the electrons are closer to their nucleus.

Ionization Energy Trend Visual

Electronegativity Review Vocabulary The tendency of an atom to attract bonding electrons to itself

Electronegativity Review Vocabulary The tendency of an atom to attract bonding electrons to itself

Electronegativity Down a Group This trend is the opposite of atomic radii. Electronegativities generally decrease as you move down a group.

Electronegativity Across a Period This trend is also the opposite of atomic radii. Electronegativities generally increase as you move across a period. This is because the Alkali Metals want to give away their single valence electron so that they will have the same electron configuration as a Noble Gas, S2P6.

Electronegativity Across a Period Continued… However, Halogens need just one electron to become like Noble Gases. Therefore, the Halogens’ tendency to attract bonding electrons is very high.

Eletronegativity Trend Visual

Trend Summary