Examen de science

Examen de science

1. Atoms

   • What is?
     • An atom is the smallest unit in matter.
   • Subparticules
     • Protons, electrons and neutrons
       • Charges
         • Protons: (+). Electrons:(-). Neutrons: no charge.
   • Atom's regions
     • Neucleus and electron cloud
       • Neucleus: Protons and neutrons
       • Electron cloud: electrons.
   • Theories
     • Democritus
       • The atom is indivisible
     • Jhon Dalton
       • The atom is indivisible and it's a solid sphere.
     • J.J. Thomson
       • Atom is divisible, he discovered electrons, he proposed the cathode ray tube experiment and the plum pudding atomic model
     • Ernest Rutherford
       • Atom is divisible, he discovered protons, proposed the gold foil experiment and the nuclear atomic model
     • Nielhs Bohr
       • He proposed the solar system atomic model, the energy levels also called orbits that the energy decrease from the outer to the inner orbit and the outer orbit is called the Valence shell.
   • Calculation
     • The atomic number is the same number of protons
     • The mass number is the addition of the protons and the neutrons
     • In most of the cases the electrons and protons have the same amount of particles in an atom
     • The net charge represented as: +x; means that it has x more protons than electrons and: -x; meand that it has x more electrons than protons.