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Basic Chemistry

Basic Chemistry. Atoms, Elements and How They Behave. In this Universe…. There is……. Matter – anything that has MASS and takes up space. Space – what is not matter. Which is there more of????. Where did matter come from?. Big Bang Approx. 13 BYA Produced enormous amounts of energy!

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Basic Chemistry

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  1. Basic Chemistry Atoms, Elements and How They Behave

  2. In this Universe….. • There is……. • Matter – anything that has MASS and takes up space. • Space – what is not matter. • Which is there more of????

  3. Where did matter come from? • Big Bang • Approx. 13 BYA • Produced enormous amounts of energy! • Energy eventually “chilled” enough to form basic building blocks of matter • Evidence??? • Expanding Universe • Red-shift • Background radiation

  4. Building an atom • Atoms = basic unit of matter • Made of… • Electrons (e-) • small, no mass, negatively charged • Protons (p+) • Has mass, positively charged • Neutrons (n0) • Has mass, no (neutral) charge

  5. Atom structure Protons and Neutrons are located near the center of the atom and form the NUCLEUS Electrons orbit around the nucleus in specific electron orbitals/shells. Why are electrons attracted to the nucleus? What keeps the electrons from “crashing in?”

  6. Structure of an Atom e- Orbit N P+ Nucleus P+ N e-

  7. e e e e e Orbit e N P Nucleus P N e e e e e Structure of an Atom

  8. e N P P N e Structure of an Atom Each Orbit is a specific distance from the nucleus.

  9. KEY POINT!!!! • Atoms, can have DIFFERENT combinations of electrons, neutrons and protons! • These different combinations makes the atoms BEHAVE differently and have different properties.

  10. Introducing the elements!

  11. So where did all these different atoms come from???? • Telling the story of matter…. • Big Bang  HUGE amount of energy released • Energy “chills” and starts to form basic building blocks of matter • First atoms form  Hydrogen and Helium. • Hydrogen attracted to other hydrogen  Big balls of hydrogen • FUSION REACTION (aka stars)  smaller atoms fuse together to form heavier elements (carbon, nitrogen, phosphorus sulfur). • SUPER FUSION  In supernovas even heavier elements are formed.

  12. Where this leaves US! • Approx 5 BYA… • some leftover space debris (matter) from star cycles start to coalesce in different ways • Hydrogen collected in center starts a fusion reaction => our sun starts fusion • Circling debris coalesces to form planets, asteroid belt, moons, etc.

  13. What we have on Earth • Atoms can exist in varying forms on earth • Compounds • Two or more different atoms bonded together • Ex. H20, CH4 • Elements • substances consisting of only one type of atom. • A single atom is the smallest amount of an element you can have. • Ex. O2, H2

  14. Atomic Theories and Discoveries Dalton: Late 19th century • thought the atom was nothing more than a tiny indivisiblesphere • Rutherford: Early 20th century • Nucleus contains protons and neutrons • Number of protons dictates which element it is. • Electrons circle nucleus in orbits.

  15. Atomic Theories and Discoveries (cont.) • Neils Bohr • Electron orbits exist at only certain energy levels (distances) from the nucleus.

  16. Bohr’s view of the atom • Each orbit holds only a certain number of electrons • Orbit 1 – max 2 • Orbit 2 – max 8 • Orbit 3 - max 8

  17. Bohr’s view of the atom • Valence Electrons: • Electrons in the outermost orbit • Determine how an atom “behaves” • atoms with not completely full valences tend to interact (bond) with other atoms.

  18. Bohr’s view of the atom • Elements with full “outer shells” do not react • Noble or “Inert” gases • He, Ne, Ar, Kr, Xe, Rn

  19. Full Valence = Non reactive

  20. Not Full Valence = reactive!

  21. The Periodic Table • Key Points for what the periodic table tells us. • Atomic number • = number of protons • Atomic Mass • =“approximate” number of protons + neutrons • If atom has a charge of zero, Electrons = Protons

  22. How to read a periodic table

  23. You try it • Oxygen • Atomic # _______________ • Atomic mass ____________ • Number of • p+ ____________ • n0 ____________ • e- ____________ • Sulfur • Atomic # _______________ • Atomic mass ____________ • Number of • p+ ____________ • n0 ____________ • e- ____________

  24. Ions • When we say “atoms” we typically mean a neutral charge • number protons = number electrons • Sometimes and atom can gain or lose electrons! • now has a positive or negative charge= ION!

  25. Isotopes • Sometimes an atom of the SAME element can gain or lose neutrons • - does it change the charge? • - does it change how it behaves? • Isotopes = atoms with the same number of protons and electrons but different neutrons

  26. Compounds • Two or more atoms bonded together in a set proportion. Ie. CH4, H20, C6H12O6 MOLECULES • Single unit of a compound • Contains more than one atom, BUT can be the same type of atom (O2, N2)

  27. Compounds • Two or more different atoms bonded together. • Type of bond depends on the number of valence electrons of the atoms involved. • Ionic • Covalent Bonding Animations

  28. Types of Bonds • Ionic: one atom gives electrons to another, creates opposite charges

  29. Types of Bonds • Covalent: atoms share electrons to get full valences

  30. Bonding – depends on valence e-’s • Atoms will form bonds to get full valences • Remember: • 1st level holds 2 electrons • 2nd level holds 8 electrons • 3rd level holds 8 electrons

  31. Atoms working together to get full Valences! • Examples: Predict how/what type of bond • Na (1Ve) bonds with Cl (7Ve’s) • C (4Ve) bonds with 4H (1 Ve each) • O (6 Ve) bonds with 2H (1 Ve each)

  32. Types of Bonds • Which do you think is stronger? • Ionic: two atoms attracted by opposite charges? OR • Covalent: two atoms holding on to same electrons

  33. Mixtures vs. Compounds • Compounds have different properties than any of the elements that make it up Example: 4 H2 (gas) + 2 O2 (gas)  4 H20 (liquid) • Parts are Chemically bound • Definite proportions required • Ex. H20 means there are always two hydrogen atoms per one oxygen atom

  34. Chemical Formulas • A chemical formula tells us three things: • What elements are involved • How many atoms of each you have • How many molecules you have

  35. Chemical Formulas • Ex: 3C6H12O6 • This means there are 3 molecules of (C6H12O6) which is glucose • 1 molecule of (C6H12O6) contains 6 Carbon atoms, 12 Hydrogen atoms and 6 Oxygen atoms • So how many H’s total are represented in the formula at the top?

  36. Mixtures vs. Compounds • Mixtures have ingredients that do not chemically bind to one another • Mixture has same properties as ingredients • No definite proportions needed • Can easily be separated • Types: solution, suspension, colloid

  37. Types of Mixtures • Solution – Homogeneous mixture • equal composition throughout • 2 or more substances; solvent and solute • Solute is individual ions or molecules • Solvent is what the solute is dissolved in. • Ex: Saltwater, sugarwater

  38. Types of Mixtures • Suspension – heterogeneous • looks uniform when shaken or stirred; • Separates upon sitting (no agitation) • Ex. Blood, salad dressing

  39. Types of Mixtures • Colloid – • Mixture of very tiny particles of dispersed in another substance; • Suspended but do not settle out • Ex. Mayonnaise, fog, milk

  40. THE MOST IMPORTANT Inorganic MOLECULE OF LIFE • WATER!

  41. Properties of Water • Nearly all of life’s chemical reactions happen in water. • Water is a pretty special molecule due to some unique characteristics of the molecule

  42. Water- Polar covalent molecule • Share electrons but not equally • slight (-) charge in the O • slight (+) charge in the H’s of water

  43. Hydrogen Bonding: What’s happening? Because of the dipole (partial charges) created by the polar covalent bond H2O molecules are weakly attracted to one another This attraction is called a H-bond Bio H

  44. Properties of Water Polarity of Water movie

  45. Properties of Water • Cohesion • Water molecules stick to other water molecules • Creates a high surfacetension • Belly flop anyone?

  46. Properties of Water Adhesion • Water molecules stick to other substances with partial charge • Capillary action!

  47. Properties of Water • Universal Solvent • Polarity of water allows it to interact with neighboring polar or ionic molecules • Dissolves or suspends many substances • What will not dissolve in water?

  48. Properties of Water Universal Solvent – making salt water

  49. Properties of Water EXAMPLE NaCl + H2O  Na+ + Cl- + H2O • oxygen attracts sodium • hydrogen attracts chloride • sodium & chloride separate as ionic bonds are broken • Is this a solution, suspension or colloid?

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