History of Atoms

• Alchemy is a medieval philosophy whose aims were the transmutation of base into gold
• Democritus is the first man who had contribution in the field of chemistry
• Democritus

  he said that matter is made up to small particles, we call it atomos.
• atomos were indivisible, indestructible, and uncuttable and the smalles particle of matter.
• democritus 


  he also believed that these atoms differ in shape, size, weight, sequence, and position
• the concept of atoms refuted the idea of Empedocles that the world was composed of air, earth, fire , and water.
• John Dalton


  the father of atomic theory. he agreed with the idea of Democritus; all matter is made of atoms; atoms are indivisible
• john dalton


  proposed Dalton's atomic theory, and used the bowling ball model.
• law of conversation of mass - the most important chemical observation of the 18th century, which states that the total mass in any chemical or physical change does not change
• law of definite composition - formulated by joseph proust that states when element combine to form compounds, they do so in definite proportions (fractions) by mass.
• Law of multiple proportions- states that if two elements combine to form different compounds, the different masses of one element that combine with a fixed mass of another element can be expressed as a ratio of small whole numbers such as 1:2, 2:3
• Law of conservation destroy states that an atom cannot be created or destroy
• J.J Thompson


  in 1987, he discovered the electrons, and developed the plum pudding model
• J.J Thompson

  he proposed a model where an atom as a positively charged sphere where the electrons are embedded
• Ernest Rutherford 


  In 1912, he discovered the protons. he devised the nuclear model
• ernest rutherford


  in this model, the posivitely charged is held in an extremely small area called the nucleus
• James Chadwick 


  In 1930, he improved the nuclear model. He also discovered the neutrons.
• Niels Bohr


  he decrived the movement of the electrons, and compared it to the planets. he devised the planetary model or the solar system model. where an atom has a nucleus made up of protons and neutrons , with atoms distributed at energy levels.
• Planetary model


  where an atom has a nucleus made up of protons and neutrons , with atoms distributed at energy levels.
• Erwin Schrodinger


  In 1932, he also described the motion of the electrons and developed the electron cloud model.
• Electron cloud model


  am atom consists of electrons moving around the nucleus without a fixed orbit
• Isotopes


  elements that have the same atomic number but can have different mass numbers. They have the same number of protons but different number of neutrons.
• Isotopes have the same number of protons but have different number of neutrons
• Isotopes has a characteristics of : Protium, Deuterium, and Tritium
• Protium is for hydrogenation; a process where molecular hydrogen is added to react with other compound to treat substances
• Deuterium is used in prototype fusion reactors and has their application in military, industrial, and scientific fields
• Tritium is used as fuel in some nuclear fusion reactions
• Molecules are a combination of two or more atoms that are chemically bonded
• Molecules can be classified as monatomic, diatomic, polytomic
• Monotomic molecule are composed of a single atom only
• diatomic molecules are composed of two atoms from either a single element or from two different elements
• polyatomic molecules consists of more that two atoms form one or more elements
• Ion is an atom or molecule with a positive and negative charge. it is formed when a NEUTRAL atom loses or gains one or more electrons
• Ions is where the number of protons is not equal to the number of electrons
• Two types of ions: cation and anion
• cation are positive ion and is formed when a neutral atom loses one or more electrons
• anion are negative ion and is formed when a neutral atom gains one or more electrons
• Electron configuration describes where electrons are located around the nucleus of an atom
• components of electron configuration: energy level/shell, energy sub-level/sub-shell/orbitals, and number of electrons in sub-level
• Electron configurations are a very important factor in determining the chemical properties of an atom