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Chemistry and Life

Chemistry and Life. The Periodic Table. Atomic Number: Number of Protons and Electrons. Atomic mass: Mass relative to Carbon-12. Chemical Bonding. HUGE: ONLY THE ELECTRONS ARE INVOLVED IN MAKING CHEMICAL BONDS!!!. More specifically, the only the one’s on the outermost “shell”. Covalent Bond.

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Chemistry and Life

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  1. Chemistry and Life

  2. The Periodic Table Atomic Number: Number of Protons and Electrons Atomic mass: Mass relative to Carbon-12

  3. Chemical Bonding • HUGE: ONLY THE ELECTRONS ARE INVOLVED IN MAKING CHEMICAL BONDS!!! More specifically, the only the one’s on the outermost “shell”

  4. Covalent Bond • Covalent bonds are generally when two or more atoms share one or more pairs of electrons.

  5. Nonpolar Covalent Bond • when these shared pairs of electrons are shared EQUALLY!

  6. Polar Covalent Bond • when these shared pairs of electrons are NOT shared equally!

  7. Common Polar Covalent Bond???

  8. Ionic Bond • bond formed between oppositely charged ions. This happens when the stronger atom steals 1+ electrons from the weaker atom. • They both have their outer shells filled, so all is good.

  9. Ions • Cl- is such a beast that it pulls the outer electron from Na. Now both are happy. • They are both now ions. Chlorine Sodium

  10. Hydrogen Bonds • These are weak bonds that are caused by the weak positive charge of the hydrogen atom to other negative atoms.

  11. Solutes and Solvents • Which is the solute and which is the solvent?

  12. Solutes and Solvents • Solute: The stuff the gets dissolved • Solvent: The stuff that does the dissolving

  13. The Mole: A Measurement of Matter • OBJECTIVES: • Distinguish between the atomic mass of an element and its molar mass.

  14. How do we measure items? • You can measure mass, • or volume, • or you can count pieces. • We measure mass in grams. • We measure volume in liters. • We count pieces in MOLES.

  15. What is the mole? We’re not talking about this kind of mole!

  16. Moles (is abbreviated: mol) • It is an amount, defined as the number of carbon atoms in exactly 12 grams of carbon-12. • 1 mole = 6.02 x 1023 of the representative particles. • Treat it like a very large dozen • 6.02 x 1023 is called: Avogadro’s number.

  17. Similar Words for an amount • Pair: 1 pair of shoelaces = 2 shoelaces • Dozen: 1 dozen oranges = 12 oranges • Gross: 1 gross of pencils = 144 pencils • Ream: 1 ream of paper = 500 sheets of paper

  18. Examples • Calculate the molar mass of the following and tell what type it is: Na2S N2O4 C Ca(NO3)2 C6H12O6 (NH4)3PO4 = 78 g/mol gram formula mass = 92 g/mol gram molecular mass = 12 g/mol gram atomic mass = 164 g/mol gram formula mass = 180 g/mol gram molecular mass = 149 g/mol gram formula mass

  19. For example • How many moles is 5.69 g of NaOH?

  20. For example • How many moles is 5.69 g of NaOH? • We need to change 5.69 grams NaOH to moles

  21. For example • How many moles is 5.69 g of NaOH? • We need to change 5.69 grams NaOH to moles • 1mole Na = 23 g 1 mol O = 16 g 1 mole of H = 1 g

  22. For example • How many moles is 5.69 g of NaOH? • We need to change 5.69 grams NaOH to moles • 1mole Na = 23 g 1 mol O = 16 g 1 mole of H = 1 g • 1 mole NaOH = 40 g

  23. For example • How many moles is 5.69 g of NaOH? • We need to change 5.69 grams NaOH to moles • 1mole Na = 23 g 1 mol O = 16 g 1 mole of H = 1 g • 1 mole NaOH = 40 g

  24. For example • How many moles is 5.69 g of NaOH? • We need to change 5.69 grams NaOH to moles • 1mole Na = 23 g 1 mol O = 16 g 1 mole of H = 1 g • 1 mole NaOH = 40 g

  25. Chemical Reactions An Overview

  26. How do you know a reaction has taken place? • A new substance is formed • Heat is produced or absorbed • A gas is released

  27. How to write a reaction • Example: Hydrogen gas + Oxygen gas = Water

  28. Here ya go! • H2 + O2 H2O Reactants Products H2 and O2 H2O

  29. Types of Reactions • Synthesis: 2 or more substances combine to make a new one. • Example: H2 + O2 H2O

  30. Decomposition: 1 substance is broken into 2 or more substances • H2O  H2 + O2

  31. Single Displacement: One element replaces another element. • Cu + AgNO3 CuNO3 + Ag • The Silver replaced the Copper • Demo

  32. Double Displacement: Two elements switch places. Two Ions are mixed together and a precipitate is formed • A precipitate is an insoluble compound formed during the reaction • PbNO3 + KI  PbI2 + KNO3

  33. OXIDATION/ REDUCTION STUFF • OXIDATION: LOSS OF ELECTRONS • EXAMPLE: SODIUM IN THE PRESENCE OF CHLORINE • REDUCTION: GAIN OF ELECTRONS • EXAMPLE: CHLORINE IN THE PRESENCE OF SODIUM • ***THE TWO REACTIONS ALWAYS OCCUR TOGETHER!!

  34. What the heck is pH? • ACID: PROTON DONOR (BASICALLY, A DONATION OF H+ IONS. • WHAT IS H+ REALLY? • BASE: PROTON ACCEPTOR; RELEASES –OH IONS

  35. More on pH… • IT IS SIMPLE THE LOG OF THE INVERSE OF THE HYDROGEN ION CONCENTRATION. • (NOW, IN ENGLISH): THE LOWER THE pH, THE HIGHER THE [H+], THE HIGHER THE pH, THE LOWER THE [H+]. • EACH SCALE NUMBER OF pH REPRESENTS A TENFOLD INCREASE OR DECREASE IN THE [H+].

  36. Answer: 100x (10x10) Answer: 100x (10x10) Answer: 100x (10x10) EXAMPLE: HOW MUCH MORE ACIDIC IS pH=2 AS COMPARED TO pH=4? Answer= 10 x 10 = 100

  37. BUFFERS • BUFFERS: THEY RESIST A CHANGE IN pH OF A SUBSTANCE BY EITHER ACCEPTING OR DONATING H+ IONS IN THE PRESENCE OF AN ACID OR A BASE

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