《化學(xué)專業(yè)英語》課件chapter3

1、Chapter 3 Atoms, Molecules, and Ions3.1 Atoms and Ions in Combination1、Molecular and Ionic Compoundsmolecular compounds: the compounds composed of molecules as molecular compoundsIonic compounds: compounds composed of positive and negative ions held together by electrical attration. (1)The chemical

2、formula of ionic compounds gives the ratio of ions (2)The individual molecular are not ordinarily present in the ionic compounds, that is, the ionic compounds can be the individual molecular as a whole. 2、Formula for chemical compounds chemical formula: the symbols for the elements in a compound wit

3、h subscripts indicating the number of atoms of each element present. molecular compounds: represents the number of atoms in one molecule. ionic compounds: gives the ratio of ions in its simplest unit, or one formula unit. 3. Naming Chemical CompoundsChemical nomenclature: The procedure of assigning

4、names to the kinds and groups of organisms listed in a taxonomic(分類) classificationIn the Stock system: stock: chemical nomenclature 1) the name of cation: name of element + charge on the ion + ion , e.g. Cu2+ : Copper (II) ion 2) Monatomic anion : name of element + ide + ion , e.g. Cl- : chloride i

5、on O2-: Oxide ion Binary compound :二元化合物consists of only two elements. e.g. CO2 , HCl 3) Acid: name + acid , e.g. HCl: Hydrochloric acid HNO3 : Nitric acid 4) Binary molecular compound: prefix + name of each element: e.g. N2O : dinitrogen monoxidee.g. N2O5: dinitrogen pentoxide4. Chemical Equation R

6、eactant : substance that undergoing chemical changeChemical Reaction Equation: reactant + conditions +products + symbolFor example : “one phosphor 4 molecule plus six chlorine yields for molecules of phosphorus trichloride ” “Gaseous nitrogen reacts with gaseous hydrogen at 400 and 250 atm pressure

7、in the presence of ferrous oxide as a catalyst to produce gaseous ammonia”3.2 Atomic, Molecular and Molar Mass RelationshipsMolecular Mass: the sum of the atomic masses.Avogadros Number, The Mole, and Molar Mass Avogadros Number: the number of atoms in exactly 12 gram of carbon-12, equal to 6.022102

8、3 a mole of something: 6.0221023 of something. Molar Mass: the mass in grams of one mole of that substance3. Molarity (M): Molar mass in Solutions molarity: the concentration given in moles per liter of solution , with the unit “mol/L” 3.3 Composition of a Chemical Compound, Simplest and Empirical Formulas, and Molecular FormulasSimplest formula: the simplest whole-number ratio of the atoms it contains Empirical formula: simplest formula determined experimentally Molecular formula: actual number of atoms in a moleculee.g.2