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Atomic Structure

Atomic Structure. Defining the Atom. Defining the Atom Essential Question. How did the concept of the atom move from philosophy to science?. Defining the Atom. An is the smallest particle of an that retains its identity in a. Philosophy or Science?.

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Atomic Structure

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  1. Atomic Structure Defining the Atom

  2. Defining the AtomEssential Question How did the concept of the atom move from philosophy to science?

  3. Defining the Atom • An is the smallest particle of an that retains its identity in a .

  4. Philosophy or Science? • believed that matter consisted of tiny, indivisible, unchangeable particles called . • Until recent centuries the existence of the atom was a question rather than a one.

  5. Philosophy to Science • Greater in allowed for experiments which indicated the existence of atoms. • Law of Conservation of , Law of Proportions, and Law of Proportions were clues to the existence of atoms.

  6. Dalton’s Atomic Theory • 1) All are composed of tiny indivisible particles called . • 2) Atoms of one element are . The atoms of one are different from those of any other .

  7. Dalton’s Theory (cont.) • 3) Atoms of different elements can mix together, or can chemically combine in simple whole-number ratios to form . • 4) occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.

  8. Sizing Up the Atom • A copper penny contains about 2.4 x 1022 atoms. • Earth’s population measures about 6 x 109 people. • There are about 4 x 1012 times as many atoms in a penny as people on the earth.

  9. Sizing Up the Atom • A line of 100,000,000 copper atoms side by side would be only 1 cm long.

  10. Sizing Up the Atom • Sizes of atoms are expressed in (trillionths of a meter). • 1 cm is the same fractional part of 600 miles as 100 is of 1 cm!

  11. Sizing Up the Atom • Dry air contains 0.002% Neon. • Yet there are about 5 x 1017 atoms of Neon in every breath you inhale! • That’s 500,000,000,000,000,000 atoms!

  12. Sizing Up the Atom • In Summary: • Atoms are itty-bitty.

  13. Atomic Structure Structure of the Nuclear Atom

  14. Structure of the Nuclear AtomEssential Question What are the principle sub-atomic particles and what part do they play in the structure of the ?

  15. The Structure of the Nuclear Atom • Atoms are known to be . • Sub-atomic particles include neutrinos, quarks, baryons, hadrons, fermions, bosons, mesons, leptons, photons, gravitons, gluons, , and . • Not to mention Nissans, futons and croutons.

  16. The Structure of the Nuclear Atom We will be most concerned with protons, neutrons and electrons.

  17. Subatomic ParticlesThe • Discovered by • charged particles • Relative charge = 1– • Symbol = e– • 1 / 1840 the mass of a proton • Reside of the nucleus

  18. Subatomic ParticlesThe • Discovered by • charged particles • Relative charge = 1+ • Symbol = p+ • Mass of 1 atomic mass unit ()

  19. Subatomic ParticlesThe • Discovered by • charged particles • Relative charge = 0 • Symbol = n0 • Mass of 1 atomic mass unit (amu)

  20. The Atomic Nucleus • Discovered by (Gold Foil Experiment) • The tiny central core of an atom • Composed of and

  21. The Atomic Nucleus • The is highly compacted and extremely dense. • of the mass of atoms is in the . • Nuclei have a of about 2 x 108 metric tons / cm3 !

  22. Atomic Structure Distinguishing Among Atoms

  23. Distinguishing Among AtomsEssential Question What part do protons, neutrons and electrons play in the and of atoms?

  24. Atomic Number • The number of determines the identity of the element. • The number of protons is indicated by the .

  25. Mass Number • The indicates the number of protons AND neutrons in the nucleus. • How do you find the number of from the mass number of a given element?

  26. Isotopes • Isotopes are atoms of that have the same number of (the same element) but have different numbers of . • They, therefore, have mass numbers and different masses.

  27. Atomic Mass • of atoms are incredibly small and impractical to express in grams • It is more practical to compare the of to a different standard.

  28. Atomic Mass Unit • An AMU (atomic mass unit) is defined as 1/12 the mass of a atom. • Since the Carbon-12 atom is made up of 6 and 6 , an AMU is approximately equal to the mass of one proton or one neutron.

  29. Atomic Mass • An element’s atomic mass is a average mass of all the atoms in a naturally occurring sample of the element. • To calculate atomic mass, the mass of each isotope by its percent abundance (expressed as a decimal) and add the products.

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