as understanding increased
- Martin Van Buren (Wikipedia)
Martin Van Buren (/væn ˈbjʊərən/ van BURE-ən; Dutch: Maarten van Buren [ˈmaːrtə(ɱ) vɑm ˈbyːrə(n)]; December 5, 1782 – July 24, 1862) was the eighth president of the United States, serving from 1837 to 1841. A primary founder of the Democratic Party, he served as New York’s attorney general and U.S. senator, then briefly as the ninth governor of New York before joining Andrew Jackson’s administration as the tenth United States secretary of state, minister to Great Britain, and ultimately the eighth vice president from 1833 to 1837, after being elected on Jackson’s ticket in 1832. Van Buren won the presidency in 1836 against divided Whig opponents. Van Buren lost re-election in 1840, and failed to win the Democratic nomination in 1844. Later in his life, Van Buren emerged as an elder statesman and an anti-slavery leader who led the Free Soil Party ticket in the 1848 presidential election.
- Plum pudding model (Wikipedia)
The plum pudding model was the first scientific model of the atom to describe an internal structure. It was first proposed by J. J. Thomson in 1904 following his discovery of the electron in 1897, and was rendered obsolete by Ernest Rutherford’s discovery of the atomic nucleus in 1911. The model tried to account for two properties of atoms then known: that there are electrons, and that atoms have no net electric charge. Logically there had to be an equal amount of positive charge to balance out the negative charge of the electrons. As Thomson had no idea as to the source of this positive charge, he tentatively proposed that it was everywhere in the atom, and that the atom was spherical. This was the mathematically simplest hypothesis to fit the available evidence, or lack thereof. In such a sphere, the negatively charged electrons would distribute themselves in a more or less even manner throughout the volume, simultaneously repelling each other while being attracted to the positive sphere’s center.
