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Introduction to Chemistry: Atomic Structure Basics

Explore the atomic structure, including the nucleus with protons and neutrons, electrons in energy levels, and how to calculate neutrons. Learn about isotopes, the periodic table, metals, nonmetals, metalloids, and transition metals. Discover Lewis Dot Structures and electron configurations.

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Introduction to Chemistry: Atomic Structure Basics

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  1. Intro to Chemistry

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

  3. Bohr Model of Atom

  4. 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 = SAVE 4th energy level = FOR CHEMISTRY!!

  5. Subatomic Particles Organized

  6. Subatomic Particle Organized Atomic Mass

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

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

  9. Chemistry tidbits • Atomic number = number of protons • Mass number = # protons + # neutrons • Don’t bother to weigh the air inside the box • So how can you calculate NEUTRONS??

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

  11. Chemistry tidbits • Usually can assume: • # protons = # electrons • ONLY true for NEUTRAL ATOMS!

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

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

  14. 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!!!

  15. 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

  16. How to write isotopes… • Mass/Hyphen Notation: • Especially important for a form of the isotope that is NOT the “usual” • Write the symbol, a dash, and the mass # for that isotope • Ex’s • C-14 • C-12

  17. How to write isotopes… • Nuclear Symbol Notation • Includes the symbol, atomic #, and the mass # for that isotope • Ex’s 14 6 C

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

  19. 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) • Metalloids- surround the stairstep line • Groups (families) – vertical columns (#1-18) • Periods – horizontal rows (#1-7)

  20. Intro to Periodic Table

  21. 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

  22. Metals-left side of table • Exist as solids at room temperature • Shiny • Good conductors of heat & electricity • Malleable (can be bent)

  23. Nonmetals-right side of table • Most are gases at room temperature • Some are brittle solids- carbon, sulfur, iodine, & phosphorus • Most donot conduct heat & electricity well

  24. Metalloids- next to zigzag line b/w metals & nonmetals • Properties fall between neighbors on both sides • Most are silvery in appearance, brittle, poor conductors of heat & electricty

  25. Transition Metals • Metals- which are less reactive than the alkali or alkaline earth metals • Often exist as oxide or sulfide ores ex. Iron sulfide or iron oxide • You’ll learn more in chemistry about these elements

  26. Major Groups on periodic table • Alkali metals- group 1- most reactive • Alkaline earth metals- group 2 • Transition metals- groups 3-12 • Metalloids- surround stairstep line • Halogens- group 17 • Noble gases-group 18 (inert gases-stable; nonreactive) • Periodic table

  27. 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

  28. Electron configurations

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