1. Johann Dobereiner • 1817-1829 Dobereiner began to cluster elements with similar properties into groups of three also known as triads. • Law of Triads- Began in 1817 when Dobereiner noticed the atomic weight of strontium, Sr, was midway between the weights of calcium and barium. These elements also had similar chemical properties. • In 1829 Dobereiner had discovered the halogen triad (chlorine, bromine and iodine) and an alkali metal triad (lithium, sodium and potassium). He proposed that nature contained triads of elements where the middle element had properties that were an average of the other two elements. This occurred when the elements were ordered in terms of atomic weight. • Later, other scientists found other triads and recognised that elements could be grouped into larger sets (more than three). However the poor accuracy of measurements for atomic weights made it difficult in grouping such elements. 2. John Newlands • Law of Octaves – 1863 Newlands proposed the Law of Octaves, which stated that elements repeated their chemical properties every ...
Although some of the elements have been known for thousands of years, our understanding of many elements is still young. Mendeleev’s first Periodic Table contained only 63 elements, and about that many were discovered in the following 100 years. Just like countries, emperors, philosophers, and cities, elements have histories, too.“The Disappearing spoon” by Sam Kean, is a detailed history of the elements on the Periodic Table. Kean does a important job of telling every single element’s journey throughout the history of mankind: from the earliest times, when chemistry was intermingled with alchemy, to these days of modern chemistry. For example: Thallium is considered the deadliest element, pretending to be potassium to gain entry into our cells where it then breaks amino acid bonds within proteins. The CIA once developed a plan to poison Fidel Castro by dosing his socks with thallium-tainted
Dalton’s atomic theory, which stated “the atoms were tiny, indivisible, indestructible particles” (Bender), differed drastically from that of the Greeks’ in that it “wasn’t just a philosophical statement that there are atoms because there must be atoms” (Bender). Although Aristotle believed that there are four terrestrial elements, earth, water, air, and fire, Democratus believed that “a piece of a substance can be divided into smaller pieces of that substance until we get down to a fundamental level at which you can’t divide the substance up and still have pieces of that substance” (“Atoms”). Aristotle’s theory was popular, but incorrect; Democratus’s was closer to our current theory, yet he remained relatively unpopular and obscure. This demonstrates of the key way in which a personal point of view can, in fact, retard the pursuit of knowledge. The scientist with the better oratory abilities has his theories more widely accepted. Dalton’s own theory, which extrapolated upon four basic
Mendelsohn was born March 21, 1887 in Olsztyn, Poland, and died on September 19, 1953. He got his start making sketches, and put himself through the Technical Academy in Munich. Although he was drafted into the army, at the start of World War 1, he did not stop drawing and sketching; by the end of the war his sketches had gained notoriety and he was hired to build and design the Hermann Hat factory in Luckenwalde, Germany. This was the beginning of Mendelsohn’s career. Mendelsohn was an expressionist, who liked to make sturdy rectangular structures that had a round centerpiece or corner. His buildings were mostly made out of concrete, steel and glass like those of most expressionists. Mendelsohn often let the form of his buildings be influenced by their function; they were never designed without their purpose being foremost in his mind. In fact, Mendelsohn was a firm believer that form follows function and not the way around, which is evident in his design for the Einstein tower. The Einsteintrum The Einsteintrum or Einstein tower is designed to house a solar observatory, to either prove or disprove Einstein’s theory of relativity and is built in 11/11/13 Potsdam, Germany. It is the first tower observatory in Europe. Mendelsohn worked with an astronomer called Erwin Finlay Freundlich, who designed it. This is Erich Mendelsohn’s most famous work and was finished in 1921. When it was finished Mendelsohn personally gave Einstein a tour of the tower, eagerly waiting for some word of Einstein’s approval, yet Einstein said nothing to Mendelsohn and later simply described it as “organic’ to the building committee. Erich search for approval steamed from the fact that he had designed the building while being inspired by “the mystique aroun...
They new the structure and particle makeup of atoms, as well as how they behaved. During the 1930Õs it became apparent that there was a immense amount of energy that would be released atoms of Gioielli 2certain elements were split, or taken apart. Scientists began to realize that if harnessed, this energy could be something of a magnitude not before seen to human eyes. They also saw that this energy could possibly be harnessed into a weapon of amazing power. And with the adven...
This showed that dissolved gases were mechanically mixed with the water and weren?t mixed naturally. But in 1803 it was found that this depended on the weight of the individual particles of the gas or atoms. By assuming the particles were the same size, Dalton was able to develop the idea of atomic weights. In 1803 this theory was finalised and stated that (1) all matter is made up of the smallest possible particles termed atoms, (2) atoms of a given element have unique characteristics and weight, and (3) three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules).
Dmitri Ivanovich Mendeleev Dmitri Mendeleev was one of the most famous modern-day scientists of all time, who contributed greatly to the world’s fields of science, technology, and politics. He helped modernize the world and set it further ahead into the future. Mendeleev also made studying chemistry easier, by creating a table with the elements and the atomic weights of them put in order by their properties. Dmitri Ivanovich Mendeleev was born in Tobolsk, Siberia, on February 7, 1834. The blonde-haired, blue-eyed boy was the son of Maria Dmitrievna Korniliev and Ivan Pavlovitch Mendeleev and the youngest of 14 children.
As elements get heavier the ratio of neutrons:protons moves away from being 1:1, Bands of instability surround the band of stability showing where the neutron:proton ratios are either to great or too small,
The writings of some Greek philosophers may be considered to be among the very first chemical theories, such as the theory that all things are composed of air, earth, fire, and water. Each of these were represented by different elements, such as sulfur, salt, mercury, and, ideally, gold. Other ideas held by alchemists were that each of the known elements were represented by heavenly bodies. Gold was earth's representation of the sun, silver for the moon, mercury for the planet Mercury, copper for Venus, iron for Mars, tin for Jupiter, and lead for Saturn.
The Atomic Theory began in roughly 400BC with Democritus in Ancient Greece and is universally believed to be correct today. Democritus who was born in 460 BC and died 370 BC and is known as the father of modern science. Democritus proclaimed that everything is made up of atoms. He continued his theory to say that atoms will always be in motion, between atoms there is empty space, atoms are unbreakable, there are an infinite number of atoms all different sizes and shapes. He also said that iron atoms are solid and strong and have hooks to lock them together, water atoms are smooth and slippery, salt atoms have sharp jagged edges because of its taste and air atoms are light and spiralling.
Dalton was the first person to develop a scientific atom theory, the ancient Greeks had ideas about the atom but could not prove it scientifically.
The next big step in the discovery of the atom was the scientific test that proved the existence of the atom. After the discovery of the atom we had the discovery of subatomic particles. With the discovery of the subatomic particles came the research, which came from experiments that were made to find out more about the subatomic particles. This research is how we uncovered that most of the weight of an atom is from its nucleus. With the gold foil experiment, tested by Ernest Rutherford, he discovered the existence of the positively charged nucleus. He proved this when the experiment was happening, a small fraction of the photons th...
Things are very different from each other, and can be broken down into small groups inside itself, which was then noticed early by people, and Greek thinkers, about 400BC. Which just happened to use words like "element', and `atom' to describe the many different parts and even the smallest parts of matter. These ideas were around for over 2000 years while ideas such as `Elements' of Earth, Fire, Air, and Water to explain `world stuff' came and went. Much later, Boyle, an experimenter like Galileo and Bacon, was influenced much by Democritus, Gassendi, and Descartes, which lent much important weight to the atomic theory of matter in the 1600s. Although it was Lavoisier who had divided the very few elements known in the 1700's into four different classes, and then John Dalton made atoms even more believable, telling everyone that the mass of an atom was it's most important property. Then in the early 1800's Dobereiner noted that the similar elements often had relative atomic masses, and DeChancourtois made a cylindrical table of elements to display the periodic reoccurrence of properties. Cannizaro then determined atomic weights for the 60 or so elements known in the 1860s, and then a table was arranged by Newlands, with the many elements given a serial number in order of their atomic weights, of course beginning with Hydrogen. That made it clear that "the eighth element, starting from a given one, is a kind of a repeat of the first", which Newlands called the Law of Octaves.
This law states that, “when elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical and physical properties” (textbook). From that, the modern periodic table was born; “each new horizontal row of the table corresponds to the beginning of a new period because a new principal energy level is being filled with electrons” (textbook).
Scientists from earlier times helped influence the discoveries that lead to the development of atomic energy. In the late 1800’s, Dalton created the Atomic Theory which explains atoms, elements and compounds (Henderson 1). This was important to the study of and understanding of atoms to future scientists. The Atomic Theory was a list of scientific laws regarding atoms and their potential abilities. Roentagen, used Dalton’s findings and discovered x-rays which could pass through solid objects (Henderson 1). Although he did not discover radiation from the x-rays, he did help lay the foundations for electromagnetic waves. Shortly after Roentagen’s findings, J.J. Thompson discovered the electron which was responsible for defining the atom’s characteristics (Henderson 2). The electron helped scientists uncover why an atom responds to reactions the way it does and how it received its “personality”. Dalton’s, Roentagen’s and Thompson’s findings helped guide other scientists to discovering the uses of atomic energy and reactions. Such applications were discovered in the early 1900’s by using Einstein’s equation, which stated that if a chain reaction occurred, cheap, reliable energy could b...