2.1Nuclear Atom

Question 1

• Matter is composed of atoms,which move through an empty space.
• Atoms are solid, homogeneous, indestructible, and indivisible.
• In Greek, the word “atom” means “indivisible”.

Answer 1

460-370 b.C Democritus

Question 2

Timeline atomic model:

Answer 2

• 460-370 b.C. Democritus
• Lavoisier. France 1782
• Joseph Proust. France 1799
• John Dalton. England 1803
• Joseph Thomson. England 1897
• Ernest Rutherford. New Zealand 1909
• Niels Bohr. Denmark 1913
• Erwin Schrödinger. Austria 1926
• Weiner Heisenberg. Germany 1927
• James Chadwick. England 1932

Question 3

• Law of conservation of mass.

- Used the scientific method

Answer 3

Lavoisier. France 1782

Question 4

Law of definite proportions

Answer 4

Joseph Proust. France 1799

Question 5

• Atomic theory
  1. Matter is composed of extremely small particles called atoms.
  2. Atoms are indivisible and indestructible
  3. Atoms of a given element are identical, in size, mass and chemicals, properties(incorrect).
  4. Atoms of a specific element are different from those of another element.
  5. Different atoms combine in simple whole-number ratios to form compounds.
  6. In a chemical reaction, atoms are separated, combined or rearranged.

Answer 5

John Dalton. England 1803

Question 6

• Identifies the electron.
• The electron has a negative charge.
• Plum pudding model.

Answer 6

Joseph Thomson. England 1897

Question 7

• Discovered the atomic nucleus, and proton, with its positive charge.
• Experiment of the gold leaf, which concludes that an atom consists of empty space through which electrons move.

Answer 7

Ernest Rutherford. New Zealand 1909

Question 8

• Published a theory of atomic structure relating the arrangement of the electrons in the atom in fixed orbits around the core, just as the planets move in orbits around the sun. Winning the Nobel prize in 1922.
• He assigned a quantum number to each orbit.

Answer 8

Niels Bohr. Denmark 1913

Question 9

• Quantum mechanical model: Electrons occupy only certain orbitals around the nucleus. Those orbitals are stable and are called “stationary” orbitals.
• Calculated energy sublevels and orbitals. Each orbital has an energy associated.
• Introduce the electron cloud model.

Answer 9

Erwin Schrödinger. Austria 1926

Question 10

The uncertainty principle: “The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.”

Answer 10

Weiner Heisenberg. Germany 1927

Question 11

• Proves the existence of neutrons.

- Determines that the atomic number is determined by the number of protons in the nucleus of the atom.

Answer 11

James Chadwick. England 1932

Question 12

Mass cannot be created or destroyed, it is merely rearranged.

Answer 12

Law of conservation of mass

Question 13

A chemical compound always contains exactly the same proportion of elements by mass.

Answer 13

Law od definite proportions

Question 14

Electrons occupy only certain orbitals around the nucleus. Those orbitals are stable and are called “stationary” orbitals.

Answer 14

Quantum mechanical model

Question 15

The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.

Answer 15

The uncertainty principle