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Chapter 4 - H

Chapter 4 - H. Atoms. 4.1 Journal – Using Analogies.

patricia-villarreal
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Chapter 4 - H

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  1. Chapter 4 - H Atoms

  2. 4.1 Journal – Using Analogies The network of blood vessels in your body is like the network of streets and highways in a large city. How are the two networks similar? Both networks are used to transport objects from one location to another. The comparison is an example of an analogy. An analogy uses a similarity to compare two objects or systems. A familiar object is often used to help explain a less familiar object. • Atoms in compounds are like bricks in a wall. Explain this analogy. • Think of and explain another analogy for atoms in compounds. • WORK ON THE “ATOMIC MATH” WORKSHEET.

  3. 4.1 Studying Atoms ANCIENT GREEKS- • DEMOCRITUS: • “atomos” = indivisible, uncut • Different types of atoms with specific properties • ARISTOTLE: • Only 4 elements • No limit to divisions

  4. 4.1 Studying Atoms DALTON’S ATOMIC THEORY:all matter is made of particles that cannot be divided Evidence: • Compounds have fixed compositions H2O 2g H always combines with 8g O 4g H always combines with 16g O

  5. 4.1 Studying Atoms DALTON’S ATOMIC THEORY:all matter is made of particles that cannot be divided • MAIN POINTS: 1) All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. H2O, CO2, CH4, H2SO4 4) A chemical reaction is a rearrangement of atoms.

  6. 4.1 Studying Atoms DALTON’S ATOMIC THEORY:

  7. 4.1 Studying Atoms THOMSON’S ATOMIC THEORY:matter is made of particles that CAN be divided • EVIDENCE: • Conducted a current thru a tube

  8. 4.1 Studying Atoms THOMSON’S ATOMIC THEORY:all matter is made of particles that CAN be divided • EVIDENCE: • No matter what metal was used, the particles had a mass 1/2000 of a Hydrogen atom. • The beam was always attracted to the positive side Hypothesis- these particles came from the atoms.

  9. 4.1 Studying Atoms - Thomson’s “plum pudding” Model The 'Plum Pudding' Model of an Atom

  10. 4.1 Studying Atoms RUTHERFORD’S ATOMIC THEORY:all atoms positive charge is concentrated in the nucleus

  11. 4.1 Studying Atoms RUTHERFORD’S ATOMIC THEORY:all atoms positive charge is concentrated in the nucleus Discovered: • Uranium emits fast moving positive particles Hypothesis: • If you shoot positive particles at gold foil (other atoms), what would happen to the particle? • Their path will not change (according to Thomson’s plum pudding)

  12. 4.1 Studying Atoms – Gold Foil Experiment

  13. 4.1 The Gold Foil Experiment RUTHERFORD’S ATOMIC THEORY all atoms positive charge is concentrated in the nucleus

  14. 4.1 Studying Atoms – Modern Atomic Theory Bohr Atom:focused on the electrons • Electrons are in energy levels • They move when the atom gains or loses energy

  15. 4.2/4.3 The Structure of the Atom & Modern Atomic Theory JOURNAL: • Work on the “Bohr Model” Worksheet from the back table. Use the Periodic Table to help you.

  16. FILL IN THE Parts of an ATOM: Subatomic particles – distinguished by mass, charge and location

  17. Subatomic particle PROPERTIES • Protons (p+): • In the nucleus • Charge of 1+ • Mass of 1 • DEFINES THE ELEMENT (equals the ATOMIC NUMBER)

  18. Protons (p+): • Atoms of DIFFERENT elements have DIFFERENT numbers of protons

  19. Subatomic particle PROPERTIES • Neutrons (n°): • In the nucleus • NO charge • Mass of 1 • Protons + neutrons = the ATOMIC MASS

  20. Neutrons (n°): • Atoms of the same element with DIFFERENT numbers of neutrons are called ISOTOPES

  21. Neutrons (n°): • ISOTOPES of Hydrogen. Same Atomic #, different Mass #

  22. Electrons (e-): • In ENERGY LEVELS around the nucleus • Charge of 1- • Mass of 1/1836 of a p+ • Equal to the number of protons • The outermost shell of electrons is called the VALENCE SHELL which holds the VALENCE ELECTRONS. Take out Bohr Diagram Sheet.

  23. Electrons (e-): • Change ENERGY LEVELS when the atom GAINS or LOSES energy The most stable electron arrangement

  24. Electrons (e-): • Current Theory – “Electron Cloud Model” (p116-17) • Shows POSSIBLE locations of electrons around nucleus • It’s a good approximation of how electrons behave

  25. Electrons (e-): ORBITALS: the most likely location of the electrons in the cloud.

  26. Electrons (e-): • Atoms of the same element with different number of ELECTRONS are called IONS

  27. IONS:form to make the outermost shell stable

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