Atomic theory presentation finale
1 like2,412 views
The document discusses the history and development of atomic theory from ancient Greek philosophers like Democritus and Leucippus, who first proposed the idea of indivisible particles called atoms, to modern scientists like Dalton, Thomson, Rutherford, and Bohr who contributed key discoveries and models that led to our current understanding. It explains concepts like atoms, elements, isotopes, atomic number, atomic mass, ions, and different atomic models including the plum pudding model, Bohr model, and electron cloud model.
Atomic theory presentation finale
- 1. By: Bulacan, Arthur Estefani, Adrian Justin
- 2. ATOM The smallest particle into which an element can be divided and still be the same substance. Atoms are so small that, until recently, no one had ever seen one. But ideas, or theories, about atoms have been around for over 2,000 years.
- 3. ELEMENT A pure substance that cannot be separated into simpler substances by physical or chemical means. Atoms make up elements. Elements are made of only one kind of atom. Elements combine to form compounds. All matter is made of elements or compounds, so all matter is made of
- 4. THEORY A unifying explanation for a broad range of hypotheses and observations that have been supported by testing. Democritus (440 B.C.) Democritus proposed that if you kept cutting a substance in half forever, eventually you would end up with an “uncuttable” particle. He called these particles atoms,
- 5. Democritus Democritus is an Ancient Greek philosopher born in Abdera, Thrace, Greece He was said to be the first step toward the current atomic theory. Hypothesized that all matter is composed of tiny indestructible units, called atoms.
- 6. His atomic theory contradicted the idea that matter can be infinitely divided. According to him, atoms cannot be divided forever. In the long run, the object will become so small and invisible that you cannot divide it any further. He said that these indivisible invisible particles are ATOMS. The word atom means not to be cut or indivisible.
- 7. TAKE NOTE! He DID NOT MAKE THE ATOMIC THEORY. He just EXPANDED it. He learned this from the founder of the atomic theory, Leucippus.
- 8. Leucippus Democritus’ teacher and Developer of theory of atomism.
- 9. Democritus thought that atoms were small, hard particles of a single material and in different shapes and sizes. He thought that atoms were always moving and formed different materials by combining with each other. Aristotle disagreed with Democritus’s idea that you would end up with an indivisible particle. Because Aristotle had greater public influence, Democritus’s ideas were ignored for centuries.
- 10. John Dalton (1803) English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory.
- 11. Scientists knew that elements combined with each other in specific proportions to form compounds. Dalton claimed that the reason for this was because elements are made of atoms.
- 12. He published his own three-part atomic theory: 1) All substances are made of atoms. Atoms are small particles that cannot be created, divided, or destroyed. 2) Atoms of the same element are exactly alike, and atoms of different elements are different. 3) Atoms join with other atoms to make new substances.
- 13. 5 POINTS of Dalton’s Theory All matter consists of tiny particles called atoms. These are indivisible and indestructible. All atoms of a given element are identical in mass and properties. The atoms of a given element are different from those of any other element; the atoms of different elements can be distinguished from one another by their respective relative atomic weights.
- 14. Compounds are formed by a combination of two or more different kinds of atoms. Compounds are pure substances. They can’t be separated into elements by phase changes because the atoms of different elements are bonded to one another and are not easily separated from one another. A chemical reaction results to rearrangement of atoms.
- 15. Joseph John “JJ” Thomson •Born on December 18 •British physicist •Discoverer of electron •Discoverer of isotopes
- 16. •Invented the mass spectrometer •Proposed first waveguide •Proposed the Plum pudding model •Awarded the 1906 Nobel Prize in Physics
- 17. •Sometimes visualized as having a cloud of positive charge, a striking contrast to the most recent atomic model, which describes the positive nucleus to be surrounded by an electron cloud. •Electrons were free to rotate within the cloud of positive substance. •These orbits were stabilized in the model by the fact that when an electron moved farther from the center of the positive cloud, it felt a larger net positive inward force, because there was more material of opposite charge, inside its orbit.
- 18. Ernest Rutherford •Born on August 30 •New Zealand chemist and physicist •Father of nuclear physics •Discovered that atoms have their positive charge concentrated in a very small nucleus. •Rutherford Model
- 19. •Gold Foil Experiment •Discoverer of proton •Awarded Nobel Prize in Chemistry in 1908 •Widely credited as splitting the atom in 1917 •Leading the first experiment to “split the nucleus”
- 20. Discover
- 21. EUGENE GOLDSTEIN •German Physicist •Early investigator of discharge tubes •Discoverer of anode rays •Credited with the discovery of proton
- 22. PROTONS • subatomic particle with an electric charge of +1 elementary charge • found in the nucleus of each atom, along with neutrons, but is also stable by itself
- 23. JAMES CHADWICK • English Nobel laureate in physics awarded for his discovery of the neutron. • Hughes Medal of the Royal Society (1932) • Nobel Prize for Physics (1935)
- 24. 1932 • Chadwick discovered a previously unknown particle in the atomic nucleus. •Particle became known as electron because of lack of electric charge
- 25. • Unlike positively charged alpha particles (consist of two protons and two neutrons bound together into a particle identical to a helium nucleus), which are repelled by the electrical forces present in the nuclei of other atoms, neutrons do not need to overcome any Coulomb barrier and can therefore penetrate and split the nuclei of even the heaviest elements.
- 26. NEUTRON •subatomic particle with no net electric charge and a mass slightly larger than that of a proton •usually found in atomic nuclei - nuclei of most atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons
- 27. ATOMIC NUMBER AND ATOMIC MASS • p- proton • n- neutron • z- atomic number • a- atomic mass
- 28. Atomic number • the number of protons in the nucleus of an atom. Ex: H1 = Hydrogen has one proton
- 29. Atomic Mass • the sum of the proton and neutron of an atom Proton + neutron = atomic mass
- 30. Additional info. •Neutrons are all identical to each other, just as protons are. • Atoms of a particular element must have the same number of protons but can have different numbers of neutrons. • When an atom does not have the same number of protons and neutrons, it is called an isotope.
- 31. ION Ion is an atom or molecule where the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge.
- 32. Atomic Models
- 33. PLUM PUDDING MODEL •Also known as the “Chocolate Chip Cookie or Blueberry Muffin Model.” •Atom is composed of electrons surrounded by a soup of positive charge to balance the electron’s negative charge, like negatively-charged “plums” surrounded by positively- charged “pudding”.
- 34. Bohr’s Model also known as the planetary model neutrons and protons are in the nucleus while the electrons are orbiting the nucleus electrons are able to jump from one orbit to another
- 35. Electron Cloud Model 1920 consists of a dense nucleus composed of protons and neutrons surrounded by electrons that exist in different clouds at the various energy levels. Erwin Schrodinger and Werner Heisenburg developed probability functions to determine the regions or clouds in which electrons would most likely be found.