The atom has three main components the protons, neutrons, and electrons. The protons and neutrons make up the nucleus, while the electrons are found outside the atom’s nucleus. Each component of an atom has a charge to it. The protons have a positive charge. The electrons have a negative charge, and the neutrons have a neutral charge.
The atoms also have a charge. For example hydrogen can be negative, positive or neutral. These are called ions. H would be a neutrally charged hydrogen atom, while H- would be a negatively charged hydrogen atom. H+ would be a positively charged hydrogen atom. The structure of an atom can tell someone what type of atom it is. For example if an atom has one proton then it is a hydrogen atom. Also if it has one electron then it will have a proton, and if it has a hundred electrons then it will have a hundred protons. You cannot take away any of its protons, neutrons or electrons without changing the type of atom. The atom is the smallest form of the elements. If we cut a piece of wood into its smallest form there would be an atom. The atom still has all of the characteristics of the original element, but it is much smaller. To best explain how small an atom is compare an atom to an apple, and the compare the apple to the Earth. The Earth is way bigger than the apple, and the apple is way bigger than the atom. The atomic number is how we classify elements on the periodic chart. The atomic number is determined by how many protons an atom has in its nucleus. That number also determines the type of element it is. For example hydrogen only has one proton so its atomic number is one, while iron has twenty six and its atomic number is twenty six. The mass number of an atom is determined by adding the protons and neutrons together. Normally the number of neutrons is the same as the number of protons, but sometimes they are different. The atoms that do have different number of protons and neutrons are called isotopes. For example a hydrogen atom that has one proton and two neutrons mass number would be 3.
John Dalton was born 1766 in Cumberland, England. He started school in a village at twelve years old. He was a teacher for ten years at a Quaker boarding school, and then he moved to Manchester. He started to write papers there and wrote a paper called Daltonism. One of his claims was to explain the law of particle pressure to chemists. This claim stated that forces of repulsion thought to cause pressure acted only between atoms of the same kind and that the atoms in a mixture were indeed different in weight and complexity. To put in English he said that forces of repulsion only acted on the same kind of atom. After all of this he proceeded to study atoms and their weights. He received many honors in his life and in Manchester over forty thousand people marched at his funeral. He died in 1844. Sir J J Thomson was born in 1856 in Manchester, England. His dad wanted him to be an engineer, but he could not pay the fee for the apprenticeship. So instead he went to Owens College. His professor recognized his mathematic ability and told him to apply for a scholar ship to Trinity College. He had first-class honors in math. He became a professor in physics. He discovered the electron in 1895. He is known as the man who split the atom. He was awarded the Nobel Prize in Physics in 1908. He made atomic science a modern science. His interest in atoms led to the discovery of the mass spectrometer that could measure the mass of an atom. This was invented by a man called Francis Aston. Thomson was a leading chemist in the field of physics. He also discovered the isotope during WWI. Then he died on August 30, 1940. He was buried in Westminster Abbey, next to Isaac Newton.
Rutherford, Ernest was born on 1871 in New Zealand. Rutherford studied under J. J. Thomson at the Cavendish Laboratory in England. His work helped create a notable landmark in the history of atomic research as he developed Bacquerel's discovery of Radioactivity into an exact and documented proof that the atoms of the heavier elements, which had been thought to be immutable, actually disintegrate into various forms of radiation.
Rutherford was the first to establish the theory of the nuclear atom and to carry out a transmutation reaction in 1919 the formation of hydrogen and oxygen isotope by bombardment of nitrogen with alpha particles. Uranium emanations were shown to consist of three types of rays, alpha of low penetrating power, beta, and gamma, of exceedingly short wavelength and great energy.
Ernest Rutherford also discovered the half-life of radioactive elements and applied this to studies of age determination of rocks by measuring the decay period of radium to lead-206.
In 1913 Bohr published a theory about the structure of the atom based on an earlier theory of Rutherford's. Rutherford had shown that the atom consisted of a positively charged nucleus, with negatively charged electrons in orbit around it. Bohr expanded upon this theory by proposing that electrons travel only in certain successively larger orbits. He suggested that the outer orbits could hold more electrons than the inner ones, and that these outer orbits determine the atom's chemical properties. Bohr also described the way atoms emit radiation by suggesting that when an electron jumps from an outer orbit to an inner one, that it emits light. Later other physicists expanded his theory into quantum mechanics. This theory explains the structure and actions of complex atoms.
Taking up research in mathematical physics, Louis de Broglie nevertheless maintained an interest in experimental physics. His brother Maurice de Broglie was at that time carrying out experimental work on X-rays and this proved a considerable interest to Louis de Broglie during the first few years of the 1920s during which he worked for his doctorate. Louis de Broglie's doctoral thesis Researches on the quantum theory of 1924 put forward this theory of electron waves, based on the work of Einstein and Planck. It proposed the theory for which he is best known, namely the particle-wave duality theory that matter has the properties of both particles and waves. After his doctorate, de Broglie remained at the Sorbonne where he taught for two years, becoming professor of theoretical physics at the Henri Poincaré Institute in 1928. From 1932 he was also professor of theoretical physics at the Faculté des Sciences at the Sorbonne. De Broglie taught there until he retired in 1962. From 1944 he was a member of the Bureau des Longitudes. In 1945 he became an adviser to the French Atomic Energy Commissariat A powerful model of the atom was developed by Erwin Schrödinger in 1926. Schrödinger combined the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom. The advantage of this model is that it consists of mathematical equations known as wave functions that satisfy the requirements placed on the behavior of electrons. The disadvantage is that it is difficult to imagine a physical model of electrons as waves.
The Schrödinger model assumes that the electron is a wave and tries to describe the regions in space, or orbitals, where electrons are most likely to be found. Instead of trying to tell us where the electron is at any time, the Schrödinger model describes the probability that an electron can be found in a given region of space at a given time. This model no longer tells us where the electron is; it only tells us where it might be.