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492 BCE
Democritus Theory
According to Democritus' atomic theory, everything is made up of atoms, which are physically indivisible: atoms are indestructible, eternal and invisible, small and unable to be diminished. He posited that atoms occupy space and differ in size, shape, magnitude, position and arrangement. In his model, atoms are homogeneous. -
460 BCE
Democritus
Democritus was born in Abdera, Thrace around 460 BC, to a wealthy family. Democritus then travel around he country to follow his interest in Natural Philosophy where his mentor came to be Leucippus, aka the founder of the atom theory. Democritus then adopted the theory of the atom. He then theorized the idea, if you cut one thing into smaller pieces that it doesn't change state. -
John Dalton
John Dalton (1766-1844) was born on September 6th, 1766, in Eaglesfield England. His family were known Quakers, He received education from his father. Later in life he was a teacher and a public speaker and shortly after perused his interest in atmospheric pressures by attending the college of William and Mary. Dalton experimented with varios gases, filling bottles full of gas, where he observed that the mixture of gases added, was the sum of partial pressures, expriments lead to Dalton's Theory -
Period: to
Electromagnetic spectrum (1800)
The electromagnetic spectrum extends from below the low frequencies used for modern radio communication to gamma radiation at the short-wavelength (high-frequency) end, thereby covering wavelengths from thousands of kilometers down to a fraction of the size of an atom. Visible light lies toward the shorter end, with wavelengths from 400 to 700 nanometres. -
Dalton's Theory
1).All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties. 3) Compounds are formed by a combination of two or more different kinds of atoms. -
JJ Thomson
Joseph John Thomson later know as JJ Thomson was born in Cheetham Hill, England, near Manchester, in 1856. JJ's father planned for him to be and engineer where he was sent to college at the age of 14. In 1894, Thomson began studying cathode rays, he demonstrated that cathode rays were negatively charged. JJ realized that the accepted model of an atom did not account for negatively or positively charged particles. Directing him to his discovery of the Thompson's Atomic Theory. -
Ernest Rutherford
Chemist and physicist Ernest Rutherford was born August 30, 1871 in Spring Grove New Zealand. He grew up on a farm spending his time either miking doing chores or swimming in the creek he was very inventive creative kid. -
Niels Bohr
Niels Bohr was born in Copenhagen, Denmark to a family of 5. Bohrs father was a professor of physiology at the university of Copenhagen. He went to study at Copenhagen majoring in physics. Rutherfords model of the atom interested Bohr so he looked into it. By basic mechanics he found that an atom couldn't be stable the electrons would lose energy and spiral into the nucleus according to Rutherford model realizing an atom must contain a constant. Which lead him to the creation of Bohr theory. -
Thomsons Theory
He developed the Plum Pudding Model before the atomic nucleus was discovered. This model shows that the electrons are surrounded by a "pudding" of positive charges to balance the negative charges. -
Bohr theory (1913)
Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy. The energy of an electron depends on the size of the orbit and is lower for smaller orbits. Radiation can occur only when the electron jumps from one orbit to another. The atom will be completely stable in the state with the smallest orbit, since there is no orbit of lower energy into which the electron can jump. -
Alchemists
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Law of Definite Proportions
law of definite proportions statement that every chemical compound contains fixed and constant proportions by weight of its constituent elements. Thomson confirmed some of them and wrote in his article “Chemistry” (1801) that had definitely proved “metals are not capable of indefinite degrees of oxidation.” The principle was then concretely formulated by the English chemist John Dalton in his chemical atomic theory (1808). -
Law of Conservation of Mass
The law of conservation of mass states that mass in its own way is neither created nor destroyed by chemical reactions or physical transformations. Which means the mass of the products in a chemical reaction must equal the mass of the reactants.
The law of conservation of mass is useful for a number of calculations and can be used to solve for unknown masses such the amount of gas given off during a reaction. -
Law of Multiple Proportions
Law of Multiple Proportions is that when two elements combine with each other to form a compound the weights with a new fixed weight . -
