W6

• Who formulated the idea that matter is made up of tiny, invisible particles called "atomos"?

  Democritus
• What was Aristotle's belief regarding matter?

  He believed matter is made up of four elements: earth, wind, water, and fire.
• What is John Dalton credited with developing in 1803?

  The first atomic model, known as the solid sphere model.
• What are Dalton's Postulates regarding atoms?

  All matter is made up of tiny, indivisible spheres called atoms, which combine to form compounds.
• What does Dalton's first postulate state?

  All matter is made up of tiny, indivisible spheres with mass called atoms.
• According to Dalton's Postulates, what happens to atoms during chemical reactions?

  Atoms remain unchanged when they enter into chemical reactions to form compounds.
• Who discovered electrons?


  Joseph John Thomson
• What is the plum-pudding model proposed by Thomson?

  It depicts electrons embedded in a uniform sphere of positive charge.
• What does the nuclear model of the atom, proposed by Rutherford, depict?

  The atom as a heavy, positively-charged nucleus with negatively-charged electrons circulating around it.
• What are covalent compounds characterized by?

  They are neutral compounds formed by the sharing of electrons.
• What is the difference between atomic number and atomic mass?

  Atomic number is the total number of protons, while atomic mass is the combined number of protons and neutrons.
• How are ionic compounds formed?

  They are formed from the attraction between charged atoms through the transfer of electrons.
• Who proposed the electron cloud model?

  Erwin Schrödinger
• What does the electron cloud model represent?

  It represents the area around an atom's nucleus where electrons are most likely to be found.
• Who discovered neutrons?


  James Chadwick
• What fundamental discovery did Chadwick make in nuclear science?

  He proved the existence of neutrons, which are elementary particles devoid of any electrical charge.
• What is Neils Bohr known for in atomic theory?

  He is known for the planetary model, which describes electrons moving around the nucleus like planets orbiting the sun.
• How did Bohr describe the movement of electrons in his planetary model?

  He said that electrons move around the nucleus at random, similar to planets orbiting the sun.
• What are the key components of Dalton's Postulates?

  • All matter is made up of atoms.
  • Atoms of the same element are identical.
  • Atoms cannot be created or destroyed.
  • Atoms combine in fixed ratios to form compounds.
• Compare the models of the atom proposed by Thomson, Rutherford, and Bohr.

  • Thomson: Plum-pudding model with electrons embedded in a positive sphere.
  • Rutherford: Nuclear model with a dense nucleus and electrons orbiting around it.
  • Bohr: Planetary model with electrons moving in defined orbits around the nucleus.