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Chemical Names and Formulas

Chemical Names and Formulas. 6.1 Introduction to Chemical Bonding 6.2 Representing Chemical Compounds 6.3 Ionic Charges 6.4 Ionic Compounds 6.5 Molecular Compounds and Acids 6.6 Naming and Formula Writing. 6.1 Objectives. Distinguish between ionic and molecular compounds

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Chemical Names and Formulas

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  1. Chemical Names and Formulas 6.1 Introduction to Chemical Bonding 6.2 Representing Chemical Compounds 6.3 Ionic Charges 6.4 Ionic Compounds 6.5 Molecular Compounds and Acids 6.6 Naming and Formula Writing

  2. 6.1 Objectives • Distinguish between ionic and molecular compounds • Define cation and anion, relate them to metal and non-metal metal/cation nonMetal/anion

  3. 6.1 Vocabulary • Molecule • Molecular compound • Ions • Cations • Anions • Ionic compounds

  4. Introduction to Chemical Bonding • Molecules and Molecular Compounds • Tend to have low boiling and melting points • May be gases or liquids at room temperature (RT) • Are composed of non-metals, CO2 • Ions and Ionic Compounds, (+) and (-) • Have balanced charges, 2(+) must have 2(-) • Have high boiling and melting points, (solid at RT) • Are composed of metals and non-metals (combined)

  5. Ions: Symbols and Names • Cations: these are metals that lose electrons • When you lose a (-) you become more positive • If Potassium (K) loses 1 electron it becomes K+1 • Example: (19+ and 19–) changes to (19+ and 18-) • Anions: these are nonMetals that gain electrons • When you gain a (-) you become more negative • If Bromine (Br) gains one electron it becomes Br-1 • Example: (35+ and 35-) changes to (35+ and 36-) • Anions change their suffix to –ide, (Bromine to Bromide)

  6. Characteristics of Compounds

  7. Questions • What is the symbol and name for an Oxygen atom that has gained two electrons? • O2- and Oxide • What is the symbol and name for an Iron atom that has lost two electrons? • Fe2+ and Iron (II)

  8. Definitions • A Molecule is the smallest electrically neutral unit of a substance • A Molecular compound are combinations of atoms • Ions are charged atoms or molecules • Cations are positively charged (+) • Anions are negatively charged (-) • Ionic compounds combine the (+) and (-)

  9. 6.2 Objectives • Distinguish among chemical formulas, molecular formulas, and formula units • Use experimental data to show that a compound obeys the law of definite proportions

  10. Vocabulary • Chemical formula • Molecular formula • Formula unit • Law of Definite Proportions • Law of Multiple Proportions

  11. Formula Unit is a crystal

  12. HONClBrIF • Diatomic Molecules, (exist as two bonded atoms) • (H) Hydrogen as H2 • (O) Oxygen as O2 • (N) Nitrogen as N2 • (Cl) Chlorine as Cl2 • (Br) Bromine as Br2 • (I) Iodine as I2 • (F) Fluorine as F2

  13. Counting Atoms and Assigning Mass • When elements react to form compounds, they react in defined, whole-number ratios. The experiments that Dalton and others performed showed that reactions are not random events; they proceed according to precise and well-defined formulas.

  14. Water, for example, is always made up of two parts hydrogen and one part oxygen. The chemical formula of a compound is written by listing the symbols of the elements together, without any spaces between them. If a molecule contains more than one atom of an element, a number is subscripted after the symbol to show the number of atoms of that element in the molecule. Thus the formula for water is H2O, never HO or H2O2.

  15. Questions • How are the images different? • In every sample of Carbon Monoxide the mass ratio is 3:4 for the mass of Carbon : Oxygen. • In sample 1: Carbon is 9 grams and Oxygen is ____ • In sample 2: Carbon is _____and Oxygen is 8 grams

  16. Definitions • A Chemical formula shows the kind and number of atoms in a representative unit • A Molecular formula shows the kind and number of atoms in a molecule • A Formula unit is the lowest whole number ratio in a compound, when ions come together to form a crystal • Law of Definite Proportions: the masses of the elements in a compound always conform to a ratio • Law of Multiple Proportions: different compounds may have different ratios of the same elements

  17. 6.3 Objectives • Use the Periodic Table to determine the charge of an ion • Define a polyatomic ion • Name the most common examples of polyatomic ions

  18. Vocabulary • Monoatomic ions • Polyatomic ions

  19. The Mono-Atomic Ions • See the table on page 143 for the Representative Elements • See the table on page 144 for some Transition Metal Elements

  20. Some Transition Metal Ions • Complexes may be quite colorful • The paint industry uses transition metal ions to provide color

  21. Poly-Atomic Ions • Ammonium ion is positive (+) • Nitrate ion is negative (-) • In each case there are multiple atoms acting as a tightly bound unit • The table on page 147 provides a good list

  22. Questions • What is the charge on a Potassium atom that has changed to an ion? • What is the charge of a Bromine atom that has changed to an ion? • Using page 147, what is the charge of Sulfite? • What is the charge of Iron (III)? • How would you write an ion of Cobalt (II)? • What is the name of Sn+4 ?

  23. Definitions • Monoatomic ions are ions consisting of only one atom • Cation: Li+1 • Anion: Br-1 • Polyatomic ions are tightly bound groups of atoms that behave as a unit and carry a charge • Cation: NH4+1 • Anion: Cr2O7-2

  24. 6.4 Objectives • Apply the rules for naming and writing formulas for binary compounds • Apply the rules for naming and writing the formulas for ternary ionic compounds

  25. Vocabulary • Binary compounds • Ternary compounds

  26. How to write a chemical formula • Start by identifying the types of atoms • Hydrogen and Oxygen • Count the atoms of each type • Two H and One O leads to the formula H2O

  27. Naming a binary ionic compound • Determine the positive ion, in this case Sodium+ • Determine the negative ion, in this case Chlorine- • Determine the charges (+) and (-), both are 1 • The positive (cation) is first, then the anion • Sodium Chloride is NaCl and has no charge

  28. Naming a ternary ionic compound • Notice the green ball, (Mg+2), and the ball that is red/white, (OH-), the ratio is 1:2 or Mg(OH)2 • Magnesium Hydroxide

  29. Definitions • Binary compounds are composed of two elements • NaCl • Ternary compounds are composed of three different elements • CaCO3

  30. 6.5 Objectives • Apply the rules for naming and writing formulas for binary molecular compounds • Name and write formulas for common acids

  31. Binary molecular compounds • Prefixes for naming binary molecular: mono- 1 di- 2 tri- 3 tetra- 4 penta- 5 hexa- 6 hepta- 7 octa-8 nona- 9 deca- 10 - diNitrogen tetraHydride, (N2H4)

  32. Naming common acids • (aq) means it is in water • Acids break apart in water • Six acids are commonly used, (see the chart at left) • There are rules for naming acids, (hydro- and –ic acids)

  33. 6.6 Objectives • Use the flowchart in Fig. 6.21 to write the name of a compound when given its chemical formula • Use the flowchart in Fig. 6.23 to write a chemical formula of a compound when given its name

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