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Intro to Chemistry

Intro to Chemistry. Periodic Table tidbits. Period table organization – organized by increasing atomic number Split into metals (left side of stair step line) and nonmetals (right side of stair step line) ONE EXCEPTION Hydrogen! vertical columns (#1-18) Groups horizontal rows (#1-7)

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Intro to Chemistry

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  1. Intro to Chemistry

  2. Periodic Table tidbits • Period table organization – organized by increasing atomic number • Split into metals (left side of stair step line) and nonmetals (right side of stair step line) • ONE EXCEPTION • Hydrogen! • vertical columns (#1-18) • Groups • horizontal rows (#1-7) • Periods

  3. Let’s Color

  4. Atomic Structure • Nucleus- center of an atom -contains protons (which are positive) -contains neutrons (which are neutral) Ex- Sodium:

  5. Atomic Structure Outside the Nucleus: • Electrons (which are negative) surround the nucleus in energy levels 1st energy level = holds 2e 2nd energy level = holds 8e 3rd energy level = holds 18e 4th energy level = holds 32e

  6. Subatomic Particles Organized

  7. Subatomic Particle Organized

  8. An atom is defined by the number of PROTONS IT HAS!!!

  9. Chemistry tidbits • Chemical Symbol- letter representing the atom (sometimes from Latin)

  10. Chemistry tidbits • Atomic number = number of protons • Don’t kill anyone in my class today! • Mass number = # protons + # neutrons • Don’t bother to weigh the air inside the box • So how can you calculate NEUTRONS??

  11. Calculating Neutrons is a simple algebraic problem… • Atomic Mass = protons + neutrons • Atomic Number = protons • Write the equation… • Atomic Mass= Atomic Number + neutrons • #Neutrons = (mass number – atomic number)

  12. Chemistry tidbits • Usually can assume: • OK to round atomic mass to nearest whole number • # protons = # electrons • ONLY true for NEUTRAL ATOMS!

  13. And remember… Don’t mess with the PROTONS!!!

  14. So what CAN we “mess with?” • Neutrons… • Changes the MASS • Get an ISOTOPE • Electrons… • Changes the CHARGE • Get an ION

  15. Atomic Mass Mystery… • Look at the atomic mass for Oxygen. What does it say (exactly?) • 15.9999 • What is the atomic mass? • P + N • So what the heck!?!?! • Average of the actual isotopes on Earth!!!

  16. Isotopes • Isotopes are different atoms of the same element that contain the same number of protons but different number of neutrons. • Examples • Cl-35 vs. Cl-37 17P 17P 18N 20N

  17. What else CAN we “mess with?” • Neutrons… • Get an ISOTOPE • Electrons… • Get an ION

  18. IONS • If you mess with the electrons you change the overall charge of the atom…an atom that is no longer neutral is called an ION. • There will be more on this to come…

  19. How do we Draw Atoms Bohr Models Lewis Dot Structures

  20. Look at the many things in your classroom or at home: desks, chairs, windows, shoes, etc. If all of these things are made from atoms and all atoms are made of only a few kinds of particles, what accounts for the variety of things that you see? Atoms of different elements have different atomic numbers. The atomic number tells us the number of protons (+ charge). If the atom is neutral, the number of electrons (-charge) equals the number of protons. The mass number is the number of protons + the number of neutrons (0 charge). In the following, C-14, the 14 is the mass number. The atomic number for C can be found on the periodic table. C’s atomic number is 6, so it has 6 protons and 6 electrons. To find the neutrons, take the mass number minus the protons (14-6 = 8 neutrons). In the Bohr Model, the protons and the neutrons are placed in the atomic nucleus while the electrons orbit around the nucleus in stationary levels. Each level can hold only a certain maximum number. The 1st up to 2 electrons, the 2nd up to 8 electrons, the 3rd up to 18 electrons, and the 4th up to 32 electrons.

  21. Complete the table below using the following information given for each atom.Atom A has 3 protons and 4 neutrons.Atom B has 11 protons and 12 neutrons.Atom C has an atomic number of 19 and a mass number of 39.Atom D has an atomic number of 17 and a mass number of 35.

  22. Complete the table below using the following information given for each atom.Atom A has 3 protons and 4 neutrons.Atom B has 11 protons and 12 neutrons.Atom C has an atomic number of 19 and a mass number of 39.Atom D has an atomic number of 17 and a mass number of 35.

  23. Let’s Draw some Bohr Models!

  24. But…that can be a pain… • Most of the time we only really care about the valence electrons • Valence Electrons- electrons in the outermost shell • Also the GROUP NUMBER!!!

  25. Valence Electrons are what react!

  26. Lewis Dot Structures • Lewis dot diagrams- display the number of valence electrons (outermost electrons) around the element symbol • Used to show how atoms of different elements bond and form compounds • Hint- use group number to find valence electrons

  27. Octet Rule- All atoms want to have 8 electrons in their outer shell

  28. Electron configurations

  29. Lewis Dot Structures

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