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Writing Formulas and Naming Compounds

Writing Formulas and Naming Compounds Atoms and molecules react with one another to become more stable. Atoms become more stable by either gaining/losing electrons so that they have 8 valence electrons (full outer energy level). Na 1s 2 2s 2 2p 6 3s 1 1 valence electron

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Writing Formulas and Naming Compounds

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  1. Writing Formulas and Naming Compounds Atoms and molecules react with one another to become more stable. Atoms become more stable by either gaining/losing electrons so that they have 8 valence electrons (full outer energy level). Na 1s2 2s2 2p6 3s1 1 valence electron Cl 1s2 2s2 2p6 3s2 3p5 7 valence electrons

  2. Sodium will lose 1 e- to get 8 valence electrons (a noble gas configuration). Chlorine will gain 1e- to get 8 valence e- (a noble gas configuration). Na  Na+1 + 1e- Cl + 1e-  Cl-1 Na+1 + Cl-1  NaCl The Na+1 and Cl-1 ions have very different properties than the Na and Cl atoms.

  3. Atoms form ions by gaining or losing electrons. The metals tend to lose electrons (positive ions), the nonmetals tend to gain electrons (negative ions). The position of the element on the periodic table can help determine how many valence electrons the atom has, and what charge it will probably have when it becomes an ion.

  4. Groups and Ion Charges

  5. Ions are atoms with different numbers of protons and electrons. They are formed by either gaining or losing electrons. If an atom loses electrons, it has more protons than electrons and becomes positively charged. This is called a cation, and usually happens to the metals. If an atom gains electrons, it has more electrons than electrons and becomes negatively charged. This is called an anion, and usually happens to the nonmetals.

  6. Monatomic Ions – an ion made up of only one type of atom (H+1, Ca+2, S-2, Cl-1, …) Polyatomic Ions – an ion made up of two or more different types of atoms (NO3-1, OH-1, SO4-2, NH4+1, …) The compound Na3PO4 is made up of 3 monatomic ions (Na+1) and 1 polyatomic ion (PO4-3).

  7. Ions are named differently than elements because they have different properties. In General • Metals – the word ion is added after the name of the element. Na = sodium Na+1 = sodium ion • Nonmetals – the ending of the element is dropped, and –ide is added. • Br = bromine Br-1 = bromide • O = oxygen O-2 = oxide

  8. Ionic compounds are made from ions combining. The compound has no net charge, or is neutral, even though it is made up of both positive and negative ions. Naming compounds and writing formulas is easy if you know the names, charges and formulas of all of the ions on the ion list. If you don’t know these, you will be guessing on all of your names or formulas.

  9. Polyatomic Ions

  10. Elements with more than one charge

  11. Naming Ionic Compounds • Give the name of the positive ion, cation, including the roman numeral if appropriate followed by the name of the negative ion, anion. • Names of the cation are the same as the name of the element. • Names of monatomic anions usually end with -ide. • Names of polyatomic anions usually end with –ate.

  12. NaCl sodium chloride LiNO3 lithium nitrate CuCl copper (I) chloride CuCl2 copper (II) chloride Sr(ClO3)2 strontium chlorate MgO magnesium oxide CaSO4 calcium sulfate FeBr3 iron (III) bromide

  13. Writing correct ionic formulas • Write the cation followed by the anion • Cross the numerical charges to become the subscripts. Drop all +/- signs • If the subscripts are 1, do not write the 1. If the subscripts are multiples, reduce them. • If more than one polyatomic ion is needed, put ( ) around the polyatomic ion before adding the subscript.

  14. Ionic Compounds • Made up of positive and negative ions • Made up of metals and nonmetals • “Salts” • Will conduct electricity when dissolved in water • Electrons are transferred between atoms • Opposites attract • Positive ion always comes first

  15. Covalent Compounds • Made up of two or more nonmetals • Electrons are shared between atoms • Do not conduct electricity in water • No ions are present

  16. Prefixes

  17. Naming covalent compounds • Give the prefix telling how many of the first element (except mono-), then give the name of the first element. • Give the prefix telling how many of the second element, then give the name of the second element ending with –ide. • P2O5 CO CO2 N2O4 PCl3 ICl3 SiO2 N4Cl7

  18. Naming Acids: HX, H2X, H3X • If the anion X ends in –ide • hydro (name of anion, drop the ending) –ic acid HCl hydro chloric acid HBr hydrobromic acid H2O hydro oxic acid H2S hydro sulfuric acid • If the anion X ends in –ate • (name of the anion, drop the ending)-ic acid HNO3 nitric acid H2SO4 sulfuric acid HClO3 chloric acid HC2H3O2 acetic acid

  19. H2SO4 HCl HNO3 HC2H3O2 H3PO4 Sulfuric Acid Hydro chloric acid Nitric acid Acetic acid Phosphoric Acid Names and formulas of common acids

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