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Chapter 3 – Chemical Foundations

Chapter 3 – Chemical Foundations. Chemical Foundations – students will identify elements, ions and molecules; be able to write formulas and names for a variety of compounds. Greeks first to explain chemical changes.  All Matter made of 4 “Elements”: Fire, Earth, Water, & Air.

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Chapter 3 – Chemical Foundations

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  1. Chapter 3 – Chemical Foundations Chemical Foundations – students will identify elements, ions and molecules; be able to write formulas and names for a variety of compounds.

  2. Greeks first to explain chemical changes.  All Matter made of 4 “Elements”: Fire, Earth, Water, & Air

  3. Robert Boyle: 1st Scientist to recognize importance of careful measurements and experimentsOxygen  Most abundant element on Earth 115  current number of elements*88  # of naturally occurring elements

  4. Trace Elements  Human body needs tiny amounts of these elements  Iron [Fe] – Hemoglobin and blood

  5. ElementSymbol shorthand method of representing elements  1st letter always a CAPITAL  2nd letter always a lower case e.g. Cl or He or Fe

  6. The ATOMMODEL – changed as new discoveries were made

  7. JohnDalton – proposed Atomic Theory  proposed atom model as a tiny, SOLID sphere  All elements made up of atoms. All atoms of an element are identical. Atoms of 1 element differ from every other element.  Different atoms can combine to form compounds Atoms are indivisible. What does that mean?

  8. Compound substance composed of the atoms of two or more elements and ALWAYS contain exactly the same number of those atoms

  9. ChemicalFormula atoms areindicated by the element symbols and the number of each type of atom is indicated by a subscript e.g. H2O or NH4OH or C6H12O6 complete the Self-Check on pg. 55 in the World of Chemistry textbook

  10. J.J. Thomson  late 1890’s discovered the electron proved that e- was NEGATIVE theorized that there must be apositive area in atom because he knew that atoms were NEUTRAL

  11. William Thomson (Lord Kelvin) building on J.J. Thomson’s work, proposed the Plum Pudding atom model “Plum Pudding” modele- positive matrix

  12. Ernest Rutherford – “Gold Foil” Exp. shot alpha particles at a VERY thin piece of gold foil  amazed when MOST of the alpha particles passed right through the foil a few alpha particles were deflected small # were bounced straight back How did Rutherford interpret these seemingly “WRONG” results?

  13. Rutherford: Mass of atom located in Middle Mass in middle is Positively Charged Dense center named Nucleus Nucleus must contain Protons Protons had same size charge as electron but positive  Electrons must be located somewhere outside of nucleus

  14. Part 2Isotopes: Atoms of SAME Element a. same number of protons b. same number of electronsc. DIFFERENT # of Neutrons Chadwick proved existence ofNeutrons in nucleus of atoms

  15.  Atomic Number (Z) - # of protons in the nucleus of an atom  Mass Number (A) – SUM of theProtons and Neutrons in the nucleus of an atom

  16. A ---------- Atomic NumberX---ElementZ ---------- Mass #

  17. 6CCarbon – 6 protons, and 14 6 electronsHow many Neutrons? Z – A = Neutrons 14 – 6 = 8 neutrons

  18. Periodic Table  First Periodic Table – 1869 -- DemitriMendeleevarranged by AtomicWeightsNow arranged by Atomic Number

  19. What is the Difference between Atomic Weights and Atomic Number?  Atomic Weight is the average weight of Many atoms of an element. Atomic Number is the Number ofProtons in the Nucleus of an Atom. [and the number of electrons]  In 1869, the proton had not yet been discovered!

  20. Remember: Alkali Metals [group 1], Alkaline Earth Metals [group 2], Halogens [group 7]Noble Gases [group 8]Groups are also called families.

  21.  What is the name of all of the Metals in the middle of the Periodic Table?TransitionMetals – Almost all are solids at room temperature.

  22. Where are Metals, Nonmetals, & Metalloids located on the Periodic Table?   Most elements are the metals.  Located on the left side of Periodic TableMetals – groups 1-13Nonmetals – groups 14-16Metalloids – along the stair step line from Boron to Tellurium

  23. Physical Properties of Metals:  Metals are good conductors of both heat and electricity Malleability – can hammer into thin sheetsDuctility – can be formed as wiresLustrous – shiny appearance

  24. Nonmetals – Located on the right side of the Periodic Table small number of elements lack most of the properties of metals many are gases at room temperature

  25. Each group has a charge that represents the number of electrons in it’s outer energy level. Example: group 1 – has 1 electron in their outer level, so they will have a +1 charge; group 2 - +2; group 3 - +3; group 4 - +/- 4 [usually -4]; group 5 - -3; group 6 - -2; group 7 - -1 and group 8 – 0 since they are chemically stable and their outer energy level is full. Group 8 Group 6 Group 1 Group 2 Group 3 Group 4 Group 5 Group 7

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