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The Atom!

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The Atom!

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  1. The Atom! Unit 4, Chapter 4 Click to see more pictures of the atom

  2. And the UNIT Essential Question is… What is the structure of the atom?

  3. 460-370 B.C. I.The development of the atomic model A.Democritus 1.Greek Philosopher 2. First predicted the existence of the atom and gave the atom its name 3.“Atom” means “indivisible” 4. Stated that different atoms have different properties 5. He was laughed at and his theory was not accepted Click on picture for more info Essential question: How was the atomic model developed?

  4. 1766-1844 Click on picture for more info B. John Dalton 1.English Chemist 2. Through experimentation in 1803 he developed the first official ATOMIC THEORY 3. His theory was accepted by the world and reads as follows… Essential question: How was the atomic model developed?

  5. C C C O O O O O O O C C C John Daltons’ 1803 Atomic Theory a. Elements are composed of indivisible atoms carbon-oxygen- b. Atoms of the same element have the same mass and atoms of different elements have different masses c. Compounds contain atoms of more than one element carbon dioxide- d. Atoms of different elements always combine in the same way carbon dioxide-carbon dioxide- O C

  6. Click on picture for more info 1856-1940 Known as the plum pudding model Real plum pudding C. J. J. Thomson 1.Discovered negative subatomic particles in 1897 and named them electrons 2. Stated that the atom is a ball of positive material in which electrons are scattered See video Listen to JJ Thomson Essential question: How was the atomic model developed?

  7. Click on picture for more info 1871-1937 D. Ernest Rutherford 1. Performed his famous gold foil experiment in 1909 2. Discovered that the atom has a dense positive nucleus Essential question: How was the atomic model developed?

  8. Click on picture for more info E. Niels Bohr 1. In 1913 predicted that electrons move in fixed energy levels (orbits) around the nucleus 1885-1962 Essential question: How was the atomic model developed?

  9. 2. Electrons can change orbits as they absorb or release energy Essential question: How was the atomic model developed?

  10. Here is how it works… energy lowest energy Energy passes through the atom An electron absorbs some of that energy and moves to a higher energy level This atom is in the ground state Immediately, the electron will return to the ground state releasing that absorbed energy as light higher energy highest energy repeat

  11. Click on picture for more info F. Erwin Schrödinger 1. Predicted the electron cloud model in 1926 a. Based on complicated math b. Shows electrons in an electron cloud (area of probability) 1887-1961 2. Energy levels are 3D areas not orbits Essential question: How was the atomic model developed?

  12. Bonus info: A proton is believed to be made of 3 quarks II.The Structure of the Atom A. Protons (p+) 1. Are located in the nucleus of the atom 2. Have a charge of +1 3. Have a mass of one atomic mass unit (AMU) 4. Identify the element Essential question: What are the parts of the atom? Images from education.jlab.org

  13. 1 1836 3. Have a mass of AMU 0.0005 amu B. Electrons (e-) 1. Are located in the electron cloud 2. Have a charge of -1 Essential question: What are the parts of the atom? Images from education.jlab.org

  14. Bonus info: A neutron is believed to be made of 3 quarks C. Neutrons (n) 1. Are located in the nucleus of the atom 2. Have no charge 3. Have a mass of one AMU Essential question: What are the parts of the atom? Images from education.jlab.org

  15. Here are some more facts about subatomic particles: Bonus Info Bonus Info Essential question: What are the parts of the atom?

  16. Cl atomic number 17 Chlorine atomic mass 35.453 III.Gathering Information on an Element A. Using the periodic table atomic number-the number of protons in the nucleus atomic mass- average mass of the element as it occurs in nature (includes all isotopes) Essential question: What are the number of subatomic particles in a given element?

  17. Here are a few things to think about: Where is most of the mass found inside the atom? The nucleus • Remember that an electron is 1836 times smaller • than a proton • The mass of the electrons in an atom is insignificant. • The largest natural element is uranium which has 92 • electrons. The total mass of 92 electrons is still only • 5% of the mass of one proton. • The mass of the electrons is miniscule compared to • the mass of the nucleus • The mass of an atom is basically equal to the mass of • the nucleus which contains the protons and neutrons • The mass of an atom is called the mass number mass number- the sum of the protons and neutrons in a given atom Essential question: What are the number of subatomic particles in a given element?

  18. Cl 17 Chlorine 35.453 B. Processing the information Protons: The number of protons in an element is equal to the atomic number Chlorine has 17 protons Electrons: The number of electrons in a neutral atom is equal to the number of protons Chlorine has 17 electrons Neutrons: The number of neutrons in an atom is equal to the mass number minus the atomic number 35 – 17 = 18 Chlorine has 18 neutrons Essential question: What are the number of subatomic particles in a given element?

  19. Os 76 Osmium 190.23 Lets practice! Protons: The number of protons in an element is equal to the atomic number Osmium has 76 protons Electrons: The number of electrons in a neutral atom is equal to the number of protons Osmium has 76 electrons Neutrons: The number of neutrons in an atom is equal to the mass number minus atomic number 190 – 76 = 114 Osmium has 114 neutrons Essential question: What are the number of subatomic particles in a given element?

  20. Zr 40 Zirconium 91.224 Protons: 40 Electrons: 40 Neutrons: 91 – 40 = 51 Essential question: What are the number of subatomic particles in a given element?

  21. IV.Isotopes of Atoms A. All atoms of the same element have the same number of protons B. The number of protons never change, they give the atom its identity C. Isotopes are atoms of the same element that have a different number of neutrons Essential question: What are the different forms an atom can take?

  22. H 1 1.0079 H H H 1 1 1 1 2 3 This is how hydrogen looks on the periodic table: The Isotopes of Hydrogen protium deuterium tritium 1 p+ = e- = n = mass = p+ = e- = n = mass = 1 p+ = e- = n = mass = 1 1 1 1 0 1 2 1 amu 2 amu 3 amu Which isotope is the most common hydrogen atom in the universe? protium The atomic mass is closest to the mass of protium Why? Essential question: What are the different forms an atom can take?

  23. What is the average of the following numbers? 3 3 3 3 4 4 20 6 = + Here is why… 3.3 3’s 20 Are there more 3’s or 4’s in the problem? 3 Is the average closer to 3 or 4?

  24. Lets practice!

  25. V.Ions of Atoms A. An ion is formed when electrons are lost or gained by an atom B. An ion can be negative or positive A negative ion has gained electrons A positive ion has lost electrons oxygen atom, O oxygen ion, O-2 calcium atom, Ca calcium ion, Ca+2 p+ = 8 e- = 8 p+ = 8 e- = 10 p+ = 20 e- = 20 p+ = 20 e- = 18 No net charge (neutral) -2 charge No net charge (neutral) +2 charge Essential question: What are the different forms an atom can take?