ernest rutherford contribution to atomic theory

Scientists then need to develop a new theory or revise the current one so that it accounts for the new observation/evidence.įrom this failed hypothesis, Rutherford developed his own atomic theory. In its place, we have the new observation, the results of this experiment. When this happens, the earlier observation is incorrect. How could the densely charged high velocity alpha particles get knocked back and away by the sparse charge of the gold atoms? The emprical evidence did not back up the hypothesis made before the test.

To add to the above, the observation (made from the plum pudding model) did not make sense anymore.Some particles even scattered back towards the source. Instead of virtually no deflection in all the alpha particles, while most particles passed through unaffected, some had huge deflection angles. If it is not true, there will be significant deflection If the hypothesis is true, there would be almost no deflection. The hypothesis is about deflection of particles, so the scientists measure deflection of particles. Scientists design an experiment which applies the hypothesis, where a measurable result will tell you if it is true or not.They predict a result that almost no deflection of alpha particles will take place, because if the observation was true then the fast-moving charged alpha particles will not be deflected by the sparse, ‘cloudy’ positive charge of the gold atoms. Scientists create a hypothesis or prediction to test the observation.Scientists take an observation from an existing topic: according to the plum pudding model, atoms are neutral overall, electrons are small negatively charged particles inside the atom so the rest of the atom must be sparse, dispersed cloud of positive charge.Rutherford’s experiment is a classic example of how the scientific method works in an observation-hypothesis-experiment cycle:.Positively-charged alpha particles were fired at high-speed at a thin gold foil sheet and the way they deflected was recorded. Ernest Rutherford’s gold foil experiment was a massive breakthrough which tested Thomson’s ‘plum pudding’ model.He took the correct idea that atoms are neutral overall and devised the plum-pudding model: electrons were negatively charged ‘plum’ chunks sitting dispersed through the rest of the atom – the ‘pudding’, which must be a positively charged cloud to balance out the electrons and give the overall neutral atom.

JJ Thomson is credited with discovering the electron, as a small electrically charged part of an atom.This became the conservation of mass, which is part of our current understanding of a chemical reaction.ĭalton also made major contributions to our knowledge of chemical compounds and formulae, measuring the relative masses of elements which he found reacted together to make new chemical substances. These atoms couldn't be destroyed or created, only rearranged and combined in different ways. In the early 19th Century, John Dalton proposed his atomic theory: matter came in a variety of elements, and all the atoms of a given element were identical in mass and their other properties.Little progress was made in atomic theory until the 19th century, when a number of experiments were done and their results could be explained by atomic theory. Many cultures around the world had somewhat similar ideas – the idea that ultimately, all the complex matter in the universe is made up of much smaller, simpler substances or energies that interact with one another.īecause the technology to measure and see atoms did not exist, not many serious scientific experiments could be done to investigate them. There was also “ether”, the substance that fills empty space.Earth was cold and dry while air is hot and wet.Fire was hot and dry while water was cold and wet.These properties were held by the classical elements: However, without microscopes and other technology, in ancient Greece the best way of describing matter was by the properties that could be felt by human senses, such as hot or cold and dry or wet. The word comes from the ancient Greek “atomos” meaning indivisible. We have a detailed periodic table showing all the elements and a detailed model of the atom and its features.īut the idea of 'atoms' is thousands of years old. Today, the words ‘atom’ and ‘element’ are learned very early in chemistry and are well understood.How a coherent scientific theory is developed by observation, hypothesis and experiment.The steps in the breakthroughs to lead to our modern understanding of the atom.The key scientists involved in developing atomic theory.

Ernest rutherford contribution to atomic theory