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Chemical Names and Formulas

Chemical Names and Formulas. Chapter 7 . Chemical Formulas. Indicate the number of atoms of each kind in a compound For a molecular compound (covalent) it is the number of atoms but in an ionic compound it is the ratio of cation to anions.

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Chemical Names and Formulas

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  1. Chemical Names and Formulas Chapter 7

  2. Chemical Formulas • Indicate the number of atoms of each kind in a compound • For a molecular compound (covalent) it is the number of atoms but in an ionic compound it is the ratio of cation to anions

  3. Parenthesis are used around polyatomic ions (more than one atom) • A subscript after a parenthesis means everything inside is multiplied by the subscript • Subscripts tell the number of atoms in the molecule • Ex: Al2(SO4)3

  4. Compounds must be neutral • The positive and negative charges balance to form a zero net charge • Ex Na+ and Cl- balance to form a zero net charge when they are linked together

  5. Monatomic Ions • Formed by a single atom • The charge is usually how many electrons it either gains or gives when it fill the valence shell (Main Group) • D block elements can have multiple ions • We us a roman numeral after them to tell which ion is being used • See chart on page 205 • Ex: Copper (I) or Copper (II)

  6. Monatomic cations are their name • Lithium = Li+ • Calcium = Ca+ • Monatomic anions is the root of the name then - ide • Fluorine becomes fluoride

  7. Binary Ionic Compounds • Two different elements join together • The charges must be equal

  8. How to determine the balanced formula? • Write the cation first with the charge as a superscript. Al3+ • Write the anion second with the charge as a superscript O2- • Then cross them down Al2O3

  9. Naming them • The cation is the element name • The anion drops the ending and adds ide Al2O3 Becomes Aluminum Oxide Now Practice

  10. Stock Nomenclature • Some ions have more than one charge (oxidation number) • Use Roman numerals to indicate which charge is being used • Cu (II) Cl2 • Name of Cation+ Name of Anion Roman Numeral Cu(II)Cl2

  11. Polyatomic Ions • Oxyanions • Anion containing oxygen • Most common ones end in • -ate ex: Nitrate; Sulfate • Ions with one less charge become • -ite ex: Nitrite ; sulfite • (NO2)- Nitrate (NO3)- Nitrite • Look them up!

  12. Binary Molecular Compounds • These are COVALENTLY bonded • New system is Stock Nomenclature • Old system uses prefixes on table 7.3 in your book. There will be a quiz on these • We will go to new system but the old system is still used frequently and is the basis for the names of chemicals.

  13. The Rules • 1. Less electronegative is first • 2. First word gets the prefix for the number of atoms, except if the number is one. • 3. The second combines • A) the prefix for the number of atoms • B) the root word part of the atom • C) the suffix –ide • 4. An (a) or (o) at the end of the prefix gets dropped

  14. Examples P4 O10 Tetraphosphrous Dioxide • NO  nitrogen monoxide  nitric oxide   • NO2  nitrogen dioxide     • N2O  dinitrogen monoxide  laughing gas •  N2O4  dinitrogen tetraoxide     • PCl5  phosphorous pentachloride  

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