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The Atom http:// www.youtube.com/watch?v=yQP4UJhNn0I

The Atom http:// www.youtube.com/watch?v=yQP4UJhNn0I. The Atom. The smallest unit of matter It is composed of subatomic particles Protons (p+) Neutrons (n +/-) Electrons (e-). Inside the Atom. Nucleus

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The Atom http:// www.youtube.com/watch?v=yQP4UJhNn0I

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  1. The Atomhttp://www.youtube.com/watch?v=yQP4UJhNn0I

  2. The Atom • The smallest unit of matter • It is composed of subatomic particles • Protons (p+) • Neutrons (n +/-) • Electrons (e-)

  3. Inside the Atom • Nucleus • located in the center of the atom with electrons moving in complicated patterns around the nucleus

  4. Inside the Atom • Electron cloud • total region in space where electrons are likely to be found around the nucleus of an atom

  5. Location of Particles in the Atom • Nucleus • Protons • Neutrons • Electron Cloud • Electrons

  6. Charges of the Subatomic Particles • Proton • Positive • Neutron • neutral • Electron • Negative

  7. Charge of the Atom • Opposite charges attract • Like charges repel • Atoms are neutrally charged when # of electrons (-) = # of protons(+) • Nucleus • Positively charged due to protons • Neutrons help block repelling forces between protons • Electron cloud • Negatively charged due to electrons

  8. Electrons have Energy! • As the level of energy increases • The further from the nucleus an electron will be located • Electrons with more energy occupy higher energy levels further from the nucleus

  9. Mass of each subatomic particle • AMU • Atomic Mass Unit • Protons • 1 AMU • Responsible for mass • Neutrons • 1 AMU • Responsible for Mass • Electrons • 0 AMU • Volume of the Atom Protons + Neutrons Mass

  10. Each subatomic particle has a special job • Protons • Identify an element • Electrons • Outermost electrons (valence) determine the chemistry or reactivity of an atom • Neutrons • Responsible for Isotopes

  11. Reactivity of the Atom • The particles in the nucleus of the atom do not change in a chemical reaction. • Chemical reactions occur because the electrons around the atoms are exchanged or shared.

  12. Quarks even Smaller! • Quarks • Protons and neutrons are made of smaller parts called quarks • 6 different quarks • Arrangement of 3 quarks together makes either a proton or a neutron • Found using particle colliders

  13. Drawing Models of the Atom • Bohr Model (Model we will use in class) • Electrons travel in fixed orbits around nucleus. • Nucleus contain positive protons and neutral neutrons.

  14. Draw the Atom Practice • Sodium atom • Atomic #: • # P+ • Atomic Mass • # E- • # N+/-

  15. Draw the Atom Practice • Carbon Atom • Atomic #: • # P+ • Atomic Mass • # E- • # N+/-

  16. Brief History of the Atom • 448 B.C. Democritus: particle theory of matter; named nature’s basic particles of matter “the atom” Greek for indivisible • Aristotle succeeded Democritus and did not believe in atoms he thought all matter was continuous

  17. Brief History of the Atom • 1800s: Dalton theorized • All matter composed of atoms • Atoms of a given element have the same properties • Atoms can not be subdivided, created, or destroyed • Atoms of different elements combine to make compounds • In Chemical reactions atoms are combined, separated, or rearranged

  18. Brief History of the Atom • 1897: J.J. Thomson said atoms have smaller particles came up with “the plum pudding model” • Ernest Rutherford worked under Thomson developed the theory of the nucleus and that the mass of the atom was located in the nucleus

  19. Brief History of the Atom • Rutherford’s gold foil experiment • Fired a stream of positively charged particles at a thin sheet of gold foil • Found that 1 in 8000 particles had been deflected back to the source • Reasoned that they were deflected due to a very dense positively charged nucleus

  20. Brief History of the Atom • 1922 Niels Bohr • Boy genius who was a klutz in the lab but a true organizer of thought • Came up with the Bohr model of the atom which placed each electron in a specific energy level • Electrons move around the nucleus like planets around the sun at specific distances or energy levels

  21. Brief History of the Atom • The Wave Model • Current model based on wave mechanics • Electrons do not move in definite paths • It is impossible to determine the exact location of an electron; the probable location is determined by how much energy an electron has • Electron Cloud: • Where electrons are found • Move in random patterns around the nucleus a billion times a second • Lowest energy electrons are closest to the nucleus • High energy electrons are further from the nucleus

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