How do I measure nucleophilicity?

Nucleophilicity is measured by observing reaction rates. The quicker the reaction, the more effective the nucleophile is. The periodic trends of electronegativity and charge stability also provide useful information regarding nucleophilic strength. Among charged species, Cl− and F− are the strongest nucleophiles because they can neutralize their destabilizing negative charge by donating a lone pair to form a chemical bond.