Physical Science

Subdecks (1)

Cards (100)

  • Empedocles asserted that all things are composed of four primal elements: Earth, Air, Fire, Water
    450 BC
  • Democritus proposed that all matter is made-up of very small particles called atoms, which cannot be divided into smaller units

    400 BC
  • Aristotle proposed that all matter was continuous and can be further divided infinitely into smaller pieces

    380 to 320 BC
  • Joseph Proust proposed the Law of Definite proportion
    1799
  • John Dalton formulated the atomic theory and proposed the law of multiple proportion

    1808
  • Dimitri Mendeleev arranged the known elements in the periodic table based on the atomic mass
    1869
  • Antoine Becquerel and Marie Currie observed that radioactivity causes some atoms to break down spontaneously
    1890
  • Wilhelm Rotgen Discovered X-ray

    1895
  • Joseph John Thompson discovered electrons
    1897
  • Joseph Thomson suggests that plum pudding model of the atom (negative electron dispersed in a positive structure)

    1904
  • Robert Millikan found that the charge of an electron is equal to -1.6022 X

    1908 to 1917
  • Ernest Rutherford observed that atoms are mostly empty space

    1910 to 1911
  • Niel Bohr proposed an atomic model that shows electrons move in concentric orbits around the nucleus

    1913
  • Henry Gwyn Jeffreys Moseley used X-rays to study atomic structure

    1913
  • Ernest Rutherford discovered protons
    1919
  • James Chadwick discovered neutron
    1932
  • Democritus
    He proposed that matter could not be divided into smaller pieces forever, and that matter was made of small, hard particles he called atoms
  • Dalton
    He created the very first atomic theory, and viewed atoms as tiny solid balls
  • Thompson
    He showed that the atom was made of even smaller things, and his atomic model was known as the raisin bun model
  • Rutherford
    He discovered protons and the nucleus, and showed that atoms have positive particles in the center and are mostly empty space
  • Bohr
    He improved on Rutherford's model, and proposed that electrons move around the nucleus in specific layers or shells
  • Chadwick
    He discovered neutrons, and working with Rutherford, discovered particles with no charge called neutrons
  • Modern atomic model
    Work done since 1920 has changed the model, and the new atomic model has electrons moving around the nucleus in a cloud
  • Democritus: 'Matter could not be divided into smaller and smaller pieces forever, eventually the smallest possible piece would be obtained'
  • Atomos
    The smallest piece of matter, meaning "not to be cut"
  • Aristotle and Plato favored the earth, fire, air and water approach to the nature of matter, and their ideas held sway because of their eminence as philosophers. The atomos idea was buried for approximately 2000 years
  • Dalton's theory
    All elements are composed of atoms, atoms are indivisible and indestructible particles, atoms of the same element are exactly alike, atoms of different elements are different, compounds are formed by the joining of atoms of two or more elements
  • Thomson's Plum Pudding model
    Atoms were made from a positively charged substance with negatively charged electrons scattered about, like raisins in a pudding
  • Thomson's model

    • Thomson studied the passage of an electric current through a gas, and concluded that the negative charges came from within the atom, meaning a particle smaller than an atom had to exist. He called the negatively charged "corpuscles", today known as electrons
  • Rutherford's Gold Foil Experiment
    Rutherford fired a stream of tiny positively charged particles at a thin sheet of gold foil, and observed that most of the particles passed through the foil, meaning the gold atoms were mostly empty space. Rutherford concluded that an atom had a small, dense, positively charged center that he called the "nucleus"
  • Bohr model
    Bohr proposed an improvement on Rutherford's model, placing each electron in a specific energy level
  • Chadwick discovered the neutron in 1935
  • Wave model
    According to the theory of wave mechanics, electrons do not move about an atom in a definite path, and it is impossible to determine the exact location of an electron. The probable location of an electron is based on how much energy the electron has
  • Electron Cloud
    A space in which electrons are likely to be found, where electrons whirl about the nucleus billions of times in one second. The location of electrons depends upon how much energy the electron has, with lower energy electrons found closer to the nucleus and higher energy electrons found in the outermost energy levels
  • Lewis Dot Symbol
    It consists of the symbol of an element (representing its nucleus and inner electrons) surrounded by one or more dots, where each dot corresponds to every valence electron in an atom of the element
  • Valence electrons

    The electrons in the highest occupied energy level of the atom, which are the only electrons generally involved in bond formation
  • Intramolecular forces
    • Ionic bonds
    • Covalent bonds
    • Metallic Bonds
  • Ionic bond
    It is due to the attraction between a cation (produced when a metal loses its electron and gains a positive charge) and an anion (created by a non-metal gaining electrons and acquiring a negative charge)
  • Covalent compound

    It exists when two non-metals share electrons to attain stability as required by the octet rule, and can have single or multiple bonds
  • Polarity/Covalent bond
    A molecule or bond is polar when it has a buildup of opposite charges on opposite ends due to the unequal sharing of electrons between atoms, and is non-polar when the electrons are shared equally