The atom is the smallest unit of matter. The name “atom” comes from the Greek word atomos, which means “uncuttable.” Atomic theory states that all matter is made up of these small particles, and that these atoms, and the matter made from them, cannot be created nor destroyed, merely reshaped and reformed. Modern chemistry unofficially began in the eighteenth century. French scientist Antoine Lavoisier discovered the law of the conservation of mass c. 1785. This law states that “The total mass remains constant during a chemical change,” (Ebbing and Gammon, 7) or that matter does not simply vanish during a chemical reaction.
Shortly after Lavoisier’s discovery, Chemist John Dalton created the theory that all matter is comprised of tiny, indivisible particles called atoms. This theory is the first of four postulates proposed by Dalton. The second is that “an element is a type of matter composed of only one kind of atom” (Ebbing and Gammon, 43). This means that …show more content…
He was able to find the charge of an electron with an experiment involving passing oil through an electrically charged plate with a hole in the center. Using this newfound charge and the determined mass-to-charge value of an electron, “you obtain an electron mass of 9.109 x 10-31 kg, which is more than 1800 times smaller that the lightest atom” (Ebbing and Gammon, 47).
Some years later, in 1911, Ernest Rutherford created his nuclear model of the atom. Rutherford launched positively-charged alpha particles at a metal foil and recorded the results. Most all of the particles passed through the foil with ease, however, a small few were reflected at large angles backwards off of the foil. From this data, Rutherford was able to find that most of the mass of an atom is in the center, or nucleus. This mass is extremely compact, however, “Nuclei have diameters of about 10-15m whereas atomic diameters are about 10-10m” (Ebbing and Gammon,
Shortly after Lavoisier’s discovery, Chemist John Dalton created the theory that all matter is comprised of tiny, indivisible particles called atoms. This theory is the first of four postulates proposed by Dalton. The second is that “an element is a type of matter composed of only one kind of atom” (Ebbing and Gammon, 43). This means that …show more content…
He was able to find the charge of an electron with an experiment involving passing oil through an electrically charged plate with a hole in the center. Using this newfound charge and the determined mass-to-charge value of an electron, “you obtain an electron mass of 9.109 x 10-31 kg, which is more than 1800 times smaller that the lightest atom” (Ebbing and Gammon, 47).
Some years later, in 1911, Ernest Rutherford created his nuclear model of the atom. Rutherford launched positively-charged alpha particles at a metal foil and recorded the results. Most all of the particles passed through the foil with ease, however, a small few were reflected at large angles backwards off of the foil. From this data, Rutherford was able to find that most of the mass of an atom is in the center, or nucleus. This mass is extremely compact, however, “Nuclei have diameters of about 10-15m whereas atomic diameters are about 10-10m” (Ebbing and Gammon,