The greek scholar named Empedocles proposed that matter PDF

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I just want notes, this is literally from grade 9...

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The greek scholar named Empedocles proposed that matter was composed of four “elements”: Water, Earth, Air, Fire. These elements mixed together to yield different substances. Rust might be one part fire, and two parts earth. Unlike other Philosophers of his time, Empedocles checked his theories experimentally: Even though air is invisible, it’s not nothing, It takes up space, so it has a form. Democritus, another greek philosopher, suggested that matter could be made of tiny particles that could not be broken down any further than they already were. He would come to call these particles atoms, after the word atomos, which meant invisible in greek.Thus different elements were composed of different kinds of atoms, This was a revolutionary idea at the time. Democritus’ idea was never accepted because Socrates, an influential figure at the time. The philosopher Aristotle believed in four elements modeled despite the more recent atomic model. Aristotle's influence was son great, on so many people, that the four-element model was accepted for almost 2000 years. Do metals grow like plants, ripening into gold? Many Alchemists believed that they did. For centuries they performed numerous experiments attempting to make gold from cheap metals. An English scientist Robert Boyle, did not believe in the four element model. He devised a new definition for the word Element: “I mean by element, simple unmitigated bodies .” This became the definition we know today as: a pure substance that cannot be broken down into simpler subsStances, boyle also did not believe that air was an element but a mixture. Joseph Priestley was the first person to isolate oxygen but he did not know that oxygen is an element. Antoine Lavoisier concluded that air must be a mixture of at least 2 gases on of which was oxygen. Meanwhile, Henry Cavendish experimented by mixing metal with acid, which resulted in a flammable gas that was Lighter than air. This gas was hydrogen, the hydrogen burned with some of Henry’s air and produced water. By this time it was generally accepted that matter was made up of elements, Dalton’s atomic model for matter stated that All matter is made up of atoms Each element has it’s own kind of atom Compounds are created when atoms of different Elements link to form molecules

Atoms cannot be created, or destroyed. Dalton’s atomic model cannot explain why, on a dry winter day, you get a spark when you touch a metal door knob. Matter is able to develop positive or negative charges. A new model was developed, introducing tiny negatively charged particles that could be separated From their atoms and moved to other atoms. In 1831 Michael Faraday found that electric currents could cause chemic in some compounds and solutions. In a modified Version of dalton’s model Matter must contain positive or negative charges Opposite charges attract and a-like charges attract Atoms combine to make molecules. J.J Thompson revised the atomic model further, to explain his discovery of very light negative particles, called electrons. The new model became know as the raisin bun model: Atoms contain particles called electrons Electrons have very small mass and negative charge The rest of the atom is a sphere of positive Charge The electrons are embedded in this sphere, so that the resulting atoms are Neutral or uncharged.

Ernest Rutherford, working at Mcgill University in montreal, designed an experiment to test Thompson’s and Nagaoka’s models. He aimed a type Of radiation at a sheet of gold foil. He predicted, based on Thompson’s Raisin bun model, that the particles Would pass right through the gold foil, as indeed they did. However a small amount of the alpha particles Bounced almost straight back from The gold foil. So Ernest had to come up with a new model called the nuclear model:

An atom has a tiny, dense, positively core called the nucleus The nucleus is surrounded by rapidly moving electrons....