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400 BCE
Democritus
Democritus, 460 BCE - 370 BCE discovered that if you keep on cutting, everything must be made of tiny eternal particles. He called these Atoms. His idea laid the foundation for atomic theory, though he didn’t describe them in the way we understand atoms today. -
400 BCE
Greece
After Cyrus has been killed, his Greek mercenaries make their way back to Greece, where Sparta is so impressed with their feats in and march through Persia that they declare war on the Persians. -
John Dalton & "marble" model
John Dalton, 1766- 1844. Discovered that each element consists of its unique brand of indivisible atom. Dalton's model of the atom was a simple, solid sphere, marking a significant step in the development of atomic theory. -
Lousinia Purchase
The Louisiana Purchase was the 1803 acquisition of the territory of Louisiana by the United States from the French First Republic. -
Michael Faraday
Michael Faraday, 1791-1867 discovered that the structure of atoms is somehow related to electricity. His work provided key evidence that atoms have an internal structure capable of interacting with electricity, influencing later developments in the understanding of atomic structure, particularly the discovery of electrons. -
Eugen Goldstein
Eugen Goldstein, 1850-1930, discovered several important properties of cathode rays, which contributed to their later identification as the first subatomic particle, the electron.This discovery showed that atoms not only contain negatively charged particles (electrons), but also positively charged particles (protons). Goldstein's work helped improve the understanding of the atom's structure by revealing the presence of positive charge inside the atom. -
Slavery in Cuba
Spain officially abolished slavery in Cuba on October 7, 1886. This marked the end of the transatlantic slave trade in Spanish territories, and the decree emancipated slaves in Cuba, which was Spain's last major colony with slavery. -
JJ Thomson & “plum pudding” model
JJ Thomson, 1856-1940, discovered atoms have negative particles (electrons) using a cathode ray tube. He proposed the "plum pudding model" of the atom, where the atom was a sphere of positive charge with electrons scattered like "raisins" in a pudding. -
Robert Millikan
Robert Millikan contributed to the atomic model by measuring the electron's charge through his oil drop experiment in 1909. His work confirmed the electron's charge, helping to refine the understanding of atoms as consisting of negatively charged electrons and positively charged protons. -
Ernest Rutherford & “nuclear” model
Ernest Rutherford, 1871-1937, demonstrated the nuclear nature of atoms by measuring the deflection of alpha particles passing through a thin gold foil. He found that atoms are mostly empty space, with a tiny, dense, positively charged core at the center, which he called the nucleus. This was a major shift from the earlier atomic models, showing that the atom has a nucleus made of positive charge, while electrons orbit around it. -
Neils Bohr & "Solar System" model
Neils Bohr, 1885-1962, proposed a model of the atom in which the electron was able to occupy only certain orbits around the nucleus. This model helped explain why atoms emit light in specific colors and was a key step in developing modern quantum mechanics. -
Titanic
Titanic was launched on May 31, 1911, and began its maiden voyage from Southampton on April 10, 1912, with 2,240 people aboard. On April 15, 1912, it struck an iceberg, broke apart, and sank, resulting in the deaths of over 1,500 passengers and crew. -
Edwin Schroedinger & "electron cloud" model
Edwin Schroedinger, 1887-1961, formulated a wave equation that accurately calculated the energy levels of electrons in atoms. His key contribution was formulating the Schrödinger equation, which describes how electrons behave as both particles and waves. This equation helped explain the probability distributions of where electrons are likely to be found around the nucleus, leading to the concept of electron clouds instead of fixed orbits. -
Werner Heisenberg
Werner Heisenberg, 1901-1976, proposed the “uncertainty relation”, setting limits for how precisely the position and velocity of a particle can be simultaneously determined. This principle states that it is impossible to simultaneously know both the exact position and momentum of an electron. This challenged the earlier Bohr model, which depicted electrons in fixed orbits, and instead supported the idea that electrons exist in regions of probability rather than precise paths. -
The Great Depression
The Great Depression started with the U.S. stock market crash on October 29, 1929. It caused severe economic problems, high unemployment, and instability around the world, affecting many countries throughout the 1930s. -
James Chadwick
James Chadwick, 1891-1974, By conducting experiments with beryllium and alpha particles, Chadwick observed that the radiation produced was not deflected by electric or magnetic fields, suggesting it was neutral. This led him to conclude that a new, uncharged particle, the neutron, existed in the atomic nucleus alongside protons. -
WWII
World War II (1939-1945) was a global war between the Allies (USA, UK, Soviet Union) and the Axis (Germany, Italy, Japan). It started when Germany attacked Poland. Key events included the Holocaust, the Pearl Harbor attack, and the use of atomic bombs on Japan. The war ended in 1945 with the defeat of the Axis powers.