- James K. Polk (Wikipedia)
James Knox Polk (/poʊk/; November 2, 1795 – June 15, 1849) was the 11th president of the United States, serving from 1845 to 1849. A protégé of Andrew Jackson and a member of the Democratic Party, he was an advocate of Jacksonian democracy and extending the territory of the United States. Polk led the U.S. into the Mexican–American War, and after winning the war he annexed the Republic of Texas, the Oregon Territory, and the Mexican Cession.
- Ionic compound (Wikipedia)
In chemistry, an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions. These can be simple ions such as the sodium (Na+) and chloride (Cl−) in sodium chloride, or polyatomic species such as the ammonium and carbonate ions in ammonium carbonate. Individual ions within an ionic compound usually have multiple nearest neighbours, so are not considered to be part of molecules, but instead part of a continuous three-dimensional network. Ionic compounds usually form crystalline structures when solid.