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Section 4.2 Molecular Compounds

Section 4.2 Molecular Compounds. RECALL. Ionic Compounds: consist of positive and negative ions, formed by the transfer of electrons from a metal to a non-metal are electrolytes (conduct electricity when dissolved in water). MOLECULAR COMPOUNDS.

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Section 4.2 Molecular Compounds

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  1. Section 4.2 Molecular Compounds

  2. RECALL Ionic Compounds: • consist of positive and negative ions, formed by the transfer of electrons from a metal to a non-metal • are electrolytes (conduct electricity when dissolved in water)

  3. MOLECULAR COMPOUNDS • form when two non-metal atoms share electrons • the bond formed by the SHARING of electrons is called covalent bond • are non-electrolytes (do not conduct electricity when dissolved in water)

  4. Diatomic Molecules Diatomic molecules – made of two atoms Hydrogen H2 (gas) Nitrogen N2 (gas) Fluorine F2 (gas) Oxygen O2 (gas) Iodine I2 (solid) Chlorine Cl2 (gas) Bromine Br2 (liquid) Have No Fear Of Ice Cold Beer

  5. Consider two atoms of hydrogen H 1p 0n H 1p 0n LOSING an electron will leave H with no electrons the shared electrons spend part of their time with one hydrogen nucleus and part of their time with the other nucleus NOTE: one electron must come from each partner in the arrangement so that a PAIR is shared

  6. CARBON AND OXYGEN C O C 6p 6n O 8p 8n Lewis Dot Diagrams

  7. CARBON AND OXYGEN C O Oxygen has two electrons to share Carbon has four electrons to share

  8. CARBON AND OXYGEN O O C these pairs are shared between the atoms

  9. Valence Method • You can reach the same conclusion using the valence method used for ionic compounds • Write the symbols • Write the valence above the atoms • Criss-cross and reduce (if necessary) • Write out the formula C4+ O2- C2 O4 CO2 * doesn’t always work for molecular compounds

  10. Naming Molecular Compounds • Use Greek prefixes to indicate the number of each type of atom in the compound • GREEK PREFIXES • mono 6. hexa • 2. di 7. hepta • 3. tri 8. octa • 4. tetra 9. nano • 5. penta 10. deca

  11. Naming Molecular Compounds SOME RULES • use the Greek prefixes to represent the subscript in the final formula • “mono” is dropped if it applies to the first element listed • the ending of the second element is changed to “-ide”

  12. Naming Molecular Compounds monocarbon dioxide CO2 dropped carbon dioxide CO CO carbon monoxide silicon tetrachloride SiCl4 nitrogen triiodide Nl3

  13. Ban Dihydrogen Monoxide The Invisible Killer Dihydrogen monoxide is colorless, odorless, tasteless, and kills uncounted thousands of people every year. Most of these deaths are caused by accidental inhalation of DHMO, but the dangers of dihydrogen monoxide do not end there. Prolonged exposure to its solid form causes severe tissue damage. Symptoms of DHMO ingestion can include excessive sweating and urination, and possibly a bloated feeling, nausea, vomiting and body electrolyte imbalance. For those who have become dependent, DHMO withdrawal means certain death.

  14. Dihydrogen monoxide: • is also known as hydroxyl acid, and is the major component of acid rain. • contributes to the "greenhouse effect." • may cause severe burns. • contributes to the erosion of our natural landscape. • accelerates corrosion and rusting of many metals. • may cause electrical failures and decreased effectiveness of automobile brakes. • has been found in excised tumors of terminal cancer patients.

  15. Contamination Is Reaching Epidemic Proportions! Quantities of dihydrogen monoxide have been found in almost every stream, lake, and reservoir in America today. But the pollution is global, and the contaminant has even been found in Antarctic ice. DHMO has caused millions of dollars of property damage in the midwest, and recently California.

  16. Despite the danger, dihydrogen monoxide is often used: • as an industrial solvent and coolant. • in nuclear power plants. • in the production of styrofoam. • as a fire retardant. • in many forms of cruel animal research. • in the distribution of pesticides. Even after washing, produce remains contaminated by this chemical. • as an additive in certain "junk-foods" and other food products.

  17. The Horror Must Be Stopped! The American government has refused to ban the production, distribution, or use of this damaging chemical due to its "importance to the economic health of this nation." In fact, the navy and other military organizations are conducting experiments with DHMO, and designing multi-billion dollar devices to control and utilize it during warfare situations. Hundreds of military research facilities receive tons of it through a highly sophisticated underground distribution network. Many store large quantities for later use.

  18. Act NOW to prevent further contamination! Find out more about this dangerous chemical. What you don't know can hurt you and others throughout the world. How many people would like to sign a petition to ban dihydrogen monoxide?

  19. Homework • Read p. 152- 158 • Complete Q. 1-4 (p.156) • “Molecular Compounds” WS#11

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