Periodic Table Research Task By Kevin Shaji Part A.
You are to research the task below and submit as a written piece of work i) John Dalton proposed his atomic theory in 1808. Outline his theory. (4 marks) ii) Explain which part of Dalton’s atomic theory was later found to be incorrect. (3 marks) iii) Dalton developed a way to measure the relative atomic mass of the different elements. Using examples research and describe the meaning of the term ‘relative atomic mass’. (3 marks) i) 1) Elements are made up of tiny particles called atoms. 2) Atoms cannot be destroyed or created but can be rearranged during chemical changes.
) Atoms of a particular element are identical in mass, size, shape and other properties. 4) Atoms of different elements are different in their mass, size, shape and other properties. 5) Atoms cannot be divided into smaller particles. 6) Atoms of different elements combine in small whole-number ratios to form compounds. ii) 1) One part of Dalton’s atomic theory that was later discovered to be incorrect was the part where atoms could not be divided into smaller pieces. New research has proved that atoms can be sub-divided into sub-atomic particles like protons, neutrons and electrons. ) Due to the discovery of isotopes it has been discovered that atoms of the same element are not exactly identical.
They have different masses due to the number of neutrons. 3) Also it has been discovered that different elements have the same mass. These elements are called isobars. 4) It has been recently discovered that atoms can actually be destroyed by fission processes in atomic reactors or by atomic bombs. 5) Another defect in Dalton’s atomic theory is that not all compounds have small whole-number ratios. They can actually have large whole-number ratios as well.
ii) The relative atomic mass is defined as: “the average mass of the isotopes in a naturally occurring sample of the element, taking into account the proportion of each isotope present. ” The symbol for relative atomic mass is Ar. For example naturally occurring chlorine has two isotopes Cl-35 and Cl-37. Cl-35 has a relative abundance (which is the percentage of that isotope on Earth in relation to the total abundance of the atom on Earth) of 75% while Cl-37 has a relative abundance of 25%. To calculate the Ar you must put the above into a formula. Ar= (75/100? 35) + (25/100? 37) =35.
Another example of calculating relative atomic mass is: For an element E with the naturally occurring isotopes aE, bE, cE, and with the respective abundances of A%, B%, C% etc, the relative atomic mass (Ar) = (A/100 x a) + (B/100 x b) + (C/100 x c) Part B Leucippus Leucippus was an early pre-Socratic ancient Greek philosopher who lived sometime during the 5th century BCE. Not much of Leucippus early life is known due to the fact that not many of his dates were recorded. What we do know is that he was an Ionian Greek that studied at an Ionian school of naturalistic philosophy.
At around 440 BCE Leucippus founded a school at Abdera, which his famous pupil Democritus attended. Around this time he proposed the theory of atomism. According to this atomism, the universe is composed of two elements: the atoms and the void in which they exist and move. This theory was later explained in much greater detail by his pupil Democritus. Leucippus contributed indirectly towards the development of the periodic table since he proposed the first idea of atoms. Thanks to his ideas the foundation for the periodic table was possible.
Without his ideas the way we view the world may be completely different.Democritus Democritus was an influential pre-Socratic ancient Greek philosopher who lived from circa 460 BCE to circa 370 BCE. He inherited his father’s vast fortunes and used it to travel the world and visit many countries on his quest of knowledge.
During these trips he met many scholars who taught many lessons. When he finally came back to his native land he became interested in natural philosophy. At the around 440 BCE he became associated with a school in Abdera, which was founded by Leucippus, his mentor. His teacher was the first one to propose atoms, but Democritus later adopted this into his own atomic theory.His theory stated that everything contains tiny particles called atoms and that they were indivisible. He hypothesised that these atoms cannot be destroyed, that they were invisible that they were always and moving.
He also stated and that they differ in size, shape, mass, position, and arrangement. Democritus contributed indirectly to the development of the periodic table. His contribution helped people to understand what an atom was and helped other scientist’s further look into science of the atom, which in turn led to the creation of the atomic table.
AristotleAristotle was an ancient Greek philosopher who lived from 384 BCE to 322 BCE. He was the student of the ancient Greek philosopher Plata and the teacher to one of the greatest military commanders in the world Alexander the Great. He taught many subjects including physics, metaphysics, poetry, theatre, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology. He is considered to be one the most important figures in Western philosophy due to his writings encompassing morality, aesthetics, logic, science, politics, and metaphysics.
One of his most well-known theories is that all mater is made from five elements. These elements are fire, water, air, earth and the fifth element aether. He believed all matter was made from a combination of the four elements except the stars and planets which are made of the fifth element aether. Even though Aristotle’s theory was wrong he contributed indirectly to the periodic table. The periodic table consists of elements and he hypothesised that elements exist. John Dalton John Dalton was an English chemist, meteorologist and physicist. He was born on the 6th of September 1766 and died on the 27th of July 1844.He began to study at a local village school and at the age of 12 began to teach there.
At the age of 15, he began to teach at a Quaker school in Kendal. After teaching here for 10 years he moved to Manchester as a teacher. While there he joined the Manchester Literary and Philosophical Society, which provided him laboratory facilities. The first paper he presented was about colour blindness which he suffered from.
Dalton arrived to atomism by his fascination of meteorology. Dalton stated that the forces of repulsion thought to cause pressure acted only between atoms of the same type.From here on he proceeded to calculate the atomic weight of atoms from percentage compositions of compounds. After this he developed his own atomic theory, which completely revolutionised the way we see the world today.
Dalton contributed indirectly to the development of the periodic table. Dalton’s information on atomic weights was a huge factor in the creation the periodic table. He also proposed a chemical symbols for some elements. Without Dalton’s ground-breaking work the periodic table would not be possible. Johann DoberienerJohann Wolfgang Doberiener was a German chemist who was born on the 13th of December 1780 and died on the 24th of March 1849. Doberiener had little opportunity for formal schooling, and so he was apprenticed to a pharmacist. He began to read widely, and attended scientific lectures whenever he received the chance. In time he became a professor at the University of Jena in 1810.
During the period of 1815-29, Johann Doberiener arranged elements in order of their atomic weight. He sorted these elements into groups of three, which became known as the law of triads.He arranged them according to the atomic weight of the middle element to the average atomic weight of the remaining two. Doberiener contributed indirectly toward the development of the periodic table. Though his method was discarded due to the fact it didn’t apply to all the elements, Doberiener gave rise to new ways to classify the elements which greatly helped in the creation of the periodic table.
John Newlands John Alexander Reina Newlands was an English chemist who worked on the development of the periodic table. He was born in London on the 26th of November of 1837 and died on the 29th of July 1898.He did not study at a normal school but was rather home schooled by his father. He went on to study at the Royal College of Chemistry.
In 1863, he set up a practice as an analytical chemist and in 1868 he became the chief chemist at James Duncan’s London sugar refinery. He later left this profession and in 1864 published his concept of the periodicity of the chemical elements. He arranged all 62 elements (known at the time) into a table based upon the ascending order of the atomic weights. He observed that every 8th element in his table displayed similar properties.
He named this discovery the Law of Octaves and stated that an element exhibits behavior that is similar to the eighth element preceding/succeeding it. John Newlands contributed indirectly to the development of the periodic table. Even though Newland’s table was not accepted, his work helped to lead Mendeleev (the father of the periodic table) on the right track thus greatly contributing to creation of the periodic table. Dmitri Ivanovich Mendeleev Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He was born in Siberia in 1834 and died in 1907.He is considered the father of the periodic table because he created the first version of the periodic table of element and used it to predict elements yet to be discovered. In 1849 his family relocated to St.
Petersburg and Mendeleev entered the Main Pedagogical Institute in 1850. He studied science there and graduated in 1856. In 1863 Mendeleev was appointed to a professorship in the University he studied in. In 1864 Dmitri Mendeleev produced his greatest achievement: the periodic table of elements. He arranged the 66 elements known at the time by their atomic weight.By doing this he managed to organise them into groups possessing similar properties. If a gap existed in his table, he anticipated that a brand new element would one day be discovered and he predicted its properties. Some of the elements he predicted were later found and provided great evidence towards the accuracy of his table.
Dmitri Mendeleev contributed directly towards the development of the periodic table since he developed it. Mendeleev’s original periodic table of elements is the model of the modern day periodic table of elements and thanks to his discovery we have a greater understanding of the universe. Henry MoseleyHenry Gwyn Jeffreys Moseley was an English physicist who was born in England on the 23rd of November 1887 and died on the 10th of August 1915 at Gallipoli. As a young boy Moseley studied at Summer Fields School where he was awarded a King’s scholarship to attend Eton College. In 1906, Moseley entered Trinity College of the University of Oxford, where he earned his bachelor’s degree. In 1910, Moseley began to study under Sir Ernest Rutherford. In 1913, he moved back to Oxford, where he was given laboratory facilities.
While at Oxford, Moseley measured the x-ray spectral lines of nearly all the elements known at the time.The results of his study showed a clear and simple progression of the elements that was based on the number of protons in the atom’s nucleus, rather than the order based on atomic weights that was then the basis of the periodic table. Moseley contributed indirectly to the development of the periodic table. He discovered the atomic number of elements which revolutionised the way the elements were sorted.
Now thanks to him the modern periodic table is sorted by atomic number. Timeline of The Periodic Table 440 BCE Democritus and Leucippus put forward the idea of the atom, an indivisible particle that all matter is made of. 30 BCE Aristotle proposes his theory about the four elements which are earth, air, fire & water. He also proposes a fifth element aether, which the stars and planets were made of. 360 BCE Plato coins term the term ‘elements’. 1605 CE Sir Francis Bacon published “The Proficience and Advancement of Learning” which contained a description of what would later be known as the scientific method which is the acquirement of new knowledge or the correction of existing knowledge.
1661 CE Robert Boyle published “The Sceptical Chymist” which was a written work on the distinction between chemistry and alchemy.It also contained some of the first ideas of atoms, molecules, and chemical reactions. 1754 CE Joseph Black isolated carbon dioxide, which he called “fixed air”. 1778 CE Antoine Lavoisier wrote the first detailed list of elements. The list contained 33 elements & differentiated between metals and non-metals. 1766 CE Henry Cavendish discovered hydrogen was a colourless, odourless gas that burns and can form an explosive mixture with air.
1773–1774 CE Carl Wilhelm Scheele and Joseph Priestly independently isolated oxygen. 1803 CE John Dalton proposed “Dalton’s Law” which described the bond between the components in a mixture of gases. 828 CE Jons Jacob Berzelius created a table of atomic weights and introduced letters to represent elements. 1828 CE Johann Doberiener developed groups of 3 elements with similar properties, which he called triads. 1864 CE John Newlands organised the known elements in order of atomic weights and observed resemblances between some elements. 1864 CE Julius Lothar Meyer develops an early version of the periodic table, with 28 elements classified by valence. 1864 CE Dmitri Mendeleev produced a table based upon atomic weights but organised ‘periodically’ with elements of congruent properties under each other.
His Periodic Table included the 66 elements known at the time, classified by their atomic weights. 1894 CE William Ramsay discovered the Noble Gases. 1898 CE Marie and Pierre Curie isolated radium and polonium from pitchblende. 1900 CE Sir Ernest Rutherford discovered the cause of radioactivity was decaying atoms. 1913 CE Henry Moseley discovered the atomic number of each of the elements which changed the way the periodic table was organised.
1940 CE Edwin McMillan and Philip H. Abelson discover neptunium, the lightest and first synthesized transuranium element, found in the products of uranium fission. 1940 CEGlenn Seaborg arranged the transuranic elements (the elements after uranium in the periodic table) below the periodic table making it easier to read. Reference List tutorvista. com. Dalton’s Atomic Theory.
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