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Atomic Structure

Atomic Structure. Key. Atomic Number. 11. Na. Element symbol. Element name. Sodium. 22.99. Average atomic mass*. Key. Atomic Number Number of Protons Number of Electrons (when atom is neutrally charged) Property unique to each element. 11. Na. Sodium. 22.99. Key. 11. Na.

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Atomic Structure

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  1. Atomic Structure

  2. Key Atomic Number 11 Na Element symbol Element name Sodium 22.99 Average atomic mass*

  3. Key • Atomic Number • Number of Protons • Number of Electrons(when atom is neutrally charged) • Property unique to each element 11 Na Sodium 22.99

  4. Key 11 Na • Element symbol • Sometimes abbreviation of English name • Sometimes abbreviation of Latin/Greek name • Familiarize yourself with them and Chemistry problems will become easier Sodium 22.99

  5. Key 11 Na • Element name • What we call it Sodium 22.99

  6. Key 11 Na Sodium 22.99 Average atomic mass* • Weighted Average number of Protons and Neutrons (approximately)

  7. Subatomic Particlesthe particles that make up an atom • Protons – high mass, positive charge. Found in nucleus. • Neutrons – high mass, no charge. Found in nucleus. • Electrons – low mass, negative charge. Found orbiting around nucleus. (abbreviated e– )

  8. Basic Electrical Charge Laws + and– : Attract (pull together) –and– : Repel (push away) + and + : Repel (push away) Like charges repel and Oppositesattract

  9. An Atom Nucleus 1 proton = H = hydrogen

  10. Why doesn’t the electron fall into the nucleus? • It orbits because the electron is moving really fast around the nucleus. • Because the electron has such a low mass, even a small amount of energy makes it move very fast.

  11. An Atom Nucleus 1 proton = H = hydrogen

  12. Another Atom Size of atom Size of nucleus 2 protons = He = helium

  13. Zooming Out – Another Atom 3 protons = Li = lithium

  14. Yet Another Atom 4 protons = Be = beryllium

  15. 5 protons = B = boron

  16. 6 protons = C = carbon

  17. Valence Electrons • valence electrons – the outermost electrons. (only the electrons in the last s and porbitals). • Only the electrons in the outermost energy levels are available for bonding.

  18. Valence Electrons • How many electrons in the valence shell of a carbon atom?

  19. 6 protons = C = carbon Outer electrons = 4 e–available for bonding Inner electrons = 2 e– not available for bonding

  20. 4 electrons in valence shell

  21. How many e– in valence shell?

  22. How many e– in valence shell?

  23. How many e– in valence shell?

  24. How many e– in valence shell?

  25. How many e– in valence shell?

  26. How many e– in valence shell?

  27. How many e– in valence shell?

  28. How many e– in valence shell?

  29. Lewis Dot Structures H • Lewis dot structures are a convenient way to show how many valence electrons an atom has. • Example: Draw the Lewis dot structure for hydrogen.

  30. Lewis Dot Structures • Write the symbol for the element. • Look for the “A” number at the top of the element’s column (e.g. 5A). This is the number of valence electrons. • Draw that many dots around the symbol. Draw at most 2 dots on each side (top, bottom, left, right) • The maximum number of dots is 8. • Exception: Helium only has 2 dots. He Ne

  31. More Lewis Structure Practice • Draw the Lewis structure for oxygen. • Draw the Lewis structure for magnesium. • Draw the Lewis structure for chlorine. Mg O Cl

  32. Even More Lewis Structure Practice K • Draw the Lewis structure for carbon. • Draw the Lewis structure for potassium. • Draw the Lewis structure for phosphorus. P C

  33. K H Na Li Mg Ca Be He O S Cl Ar F P N Br Kr C Si Al Ne B I Xe

  34. 4 e– in valence shell

  35. Valence Shell • Only the electrons in the outermost energy levels are available for bonding. • valence shell – the outermost bundle of energy levels.

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