Chapter Two Atoms, molecules and Ions

Chapter Two / Atoms, molecules and Ions Chemical Formula Molecular FormulaEmpirical Formula It’s a formula shows the exact number of atoms of each elements in the smallest unit of a substance shows the simplest whole-number ratio of the atoms in a substance C 6 H 12 O 2 N 2 H 4 O 3 Cl 2 C 2 H 4 C 8 H 10 N 4 O 4 Al 2 O 3 C 3 H 6 O NH 2 O ClCH 2 C 4 H 5 N 2 O 2 Al 2 O 3

Chapter Two / Atoms, molecules and Ions

Formula of Ionic Compounds Ionic compound consist of a cation and an anion the formula is always the same as the empirical formula the sum of the charges on the cation and anion in each formula unit must equal zero The ionic compound NaCl

Chapter Two / Atoms, molecules and Ions The subscript of the cation is numerically equal to the charge on the anion, and the subscript on the anion is numerically equal to the charge on the cation Examples: Al +3 O -2 Al 2 O 3 k+k+ Br - KBr Mg +2 N -3 Mg 3 N 2 Formula of Ionic Compounds

Chapter Two / Atoms, molecules and Ions Naming compounds Compound OrganicInorganic Contain carbon usually in combination with elements such as hydrogen, oxygen and nitrogen. All other compounds There are some compounds containing carbon are also considered as inorganic such as CO 2, CO 3 - HCO 3 -, CS 2, CO, CN - IonicMolecular Acid and base hydrate

Chapter Two / Atoms, molecules and Ions Ionic Compounds Mostly metals cation + nonmetal anion Rule: Name the metal first, then the nonmetal as -ide. Example : NaCl Sodium chloride ZnI 2 Zinc iodide Al 2 O 3 Aluminum oxide Na 3 NSodium nitride KBrPotassium bromide CaO Calcium oxide MgS Magnesium sulfide NH 4 + is called ammonium

Chapter Two / Atoms, molecules and Ions Ionic Compounds + -

Chapter Two / Atoms, molecules and Ions Ionic Compounds Metal cation can be devided into two catagrories : 1- metal form one type of cation. Example: Alkali group and alkali earth group. 2- metal form more than one type of cation. Example: transient metals. (Fe +2, Fe +3 ). Rule Exceptions: If have a variable charged metal, then give its charge in the middle with a Roman Numeral in parenthesis. This called stock system. Example: FeCl 2 = Iron (II) Chloride. FeCl 3 = Iron (III) chloride

Chapter Two / Atoms, molecules and Ions Ionic Compounds Nonmetal anion can be divided into two groups: 1- monoatomic anion. Example : Cl - chloride, Br - bromide, O -2 Oxide. 2- Polyatomic anion. Example : OH - hydroxide, CN - cyanide. Common names for some anions: CO 3 -2 Carbonate, PO 4 -3 Phosphate, SO 4 -2 Sulphate HCO 3 - Bicarbonate, NO 3 - Nitrate, SO 3 -2 Sulphite

Chapter Two / Atoms, molecules and Ions Ionic Compounds

Chapter Two / Atoms, molecules and Ions

Example 1 : Name the following compounds : a)Cu(NO 3 ) 2 b) KH 2 PO 4 C) NH 4 ClO 3 b)Cu from transition metal then it have more than one form of cation, NO 3 -1 has common name nitrate thus copper (II) nitrate b) Potassium from group 1A thus it form only one type of cation, H 2 PO 4 -1 has common name dihydrogen phosphate thus Potassium dihydrogen phosphate. C) NH 4 +1 has common name ammonium, ClO 3 -1 has common name chlorate thus Ammonium chlorate Ionic Compounds

Chapter Two / Atoms, molecules and Ions Ionic Compounds Example 2: Write the chemical formula of the following compounds : a) Mercury(II) nitrite, b) cesium sulfide c) calcium phosphate. a) Hg +2 NO 2 -1 ===== Hg(NO 2 ) 2 b) Cs +1 S -2 =======Cs 2 S c) Ca +2 PO 4 -3 ========Ca 3 (PO 4 ) 2

Chapter Two / Atoms, molecules and Ions Summery of naming compound IonicMolecular Cation: metal or NH 4 + Anion: monotomic or polytomic Cation has only one charge Cation has more than one charge Alkali metal Alkaline earth metal Ag +, Al +3, Cd +2, Zn +2 Other metal cations Name metal first If monoatomic anion, add ide to the anion If polyatomic anion use name of anion from previous table Name metal first Specify charge of metal cation with roman numeral (STOCK SYSTEM) If monoatomic anion, add ide to the anion If polyatomic anion use name of anion from previous table

Chapter Two / Atoms, molecules and Ions Molecular Compounds Mostly nonmetal + nonmetal or nonmetal + metalloid Rule: Name the first element, then the second element as -ide. Example: HCl Hydrogen chloride HBr Hydrogen bromide SiC silicon carbide Its common that one pair of element can form different compounds. Example: CO SO 2 NO 2 CO 2 SO 3 N 2 O 4

Chapter Two / Atoms, molecules and Ions Molecular Compounds CO carbon oxide CO 2 carbon oxide SO 2 sulfur oxide SO 3 sulfur oxide N 2 O 4 nitorgen oxide

Chapter Two / Atoms, molecules and Ions Molecular Compounds CO carbon monoxide carbon dioxide sulfur dioxide sulfur trioxide dinitorgen tetraoxide Name as before and add the number of atom before each elements. Note that for the first element the prefix mono can be omitted. Compounds containing hydrogen are exception from this rule. Example: B 2 H 6 diborane, CH 4 methane, NH 3 ammonia, SiH 4 silane, PH 3 phosphine H 2 O water, H 2 S hydrogen sulfide CO 2 SO 2 SO 3 N 2 O 4

Chapter Two / Atoms, molecules and Ions Molecular Compounds Example1: Name the following compounds: a) PCl 3 b) CCl 4 c) P 2 Cl 5 a) Phosphorus chloride

Chapter Two / Atoms, molecules and Ions Molecular Compounds Example1: Name the following compounds: a) PCl 3 b) CCl 4 c) P 2 Cl 5 a) Phosphorus trichloride b) Carbon chloride

Chapter Two / Atoms, molecules and Ions Molecular Compounds Example1: Name the following compounds: a) PCl 3 b) CCl 4 c) P 2 Cl 5 a) Phosphorus trichloride b) Carbon tetrachloride c) phosphorus chloride

Chapter Two / Atoms, molecules and Ions Molecular Compounds Example1: Name the following compounds: a) PCl 3 b) CCl 4 c) P 2 Cl 5 a) Phosphorus trichloride b) Carbon tetrachloride c) phosphorus pentachloride

Chapter Two / Atoms, molecules and Ions Molecular Compounds Example1: Name the following compounds: a) PCl 3 b) CCl 4 c) P 2 Cl 5 a) Phosphorus trichloride b) Carbon tetrachloride c) diphosphorus pentachloride

Chapter Two / Atoms, molecules and Ions Molecular Compounds Example2: Write the chemical formula of the following compounds: a) Carbon disulfide b) disilicon hexabromide c) sulfur tetrafluoride a) CS 2 b)Si 2 Br 6 c) SF 4

Chapter Two / Atoms, molecules and Ions

Chapter Two / Atoms, molecules and Ions Summery of naming compound IonicMolecular Cation: metal or NH 4 + Anion: monotomic or polytomic Cation has only one charge Cation has more than one charge Alkali metal Alkaline earth metal Ag +, Al +3, Cd +2, Zn +2 Other metal cations Name metal first If monoatomic anion, add ide to the anion If polyatomic anion use name of anion from previous table Name metal first Specify charge of metal cation with roman numeral (STOCK SYSTEM) If monoatomic anion, add ide to the anion If polyatomic anion use name of anion from previous table Nonmetal + nonmetal Nonmetal + metalloid Pair Form one type of compound Pair Form more than one type of compound Name first element add ide to the name of second element Name first element add ide to the name of second element Add the prefix (prefix mono usually omitted for the first element

Chapter Two / Atoms, molecules and Ions homework Name these compounds: a) Na 2 CrO 4 b) K 2 HPO 4 c) HBr d) Li 2 CO 3 e) K 2 Cr 2 O 7 f) NH 4 NO 2 g) PF 3 h) PF 5 i) P 4 O 6 j) CdI 2 k) SrSO 4 l) Al(OH) 3 m) Na 2 CO 3 n) FeCl 2 o) FeO p) Fe 2 O 3

Chapter Two / Atoms, molecules and Ions homework Write the chemical formula for the following compound: a) Rubidium nitrite b) potassium sulphide c) magnesium phosphate d) calcium hydrogen phosphate e) potassium dihydrogen phosphate f) iodine heptaflouride g) ammonium sulphate h) silver perchlorate i) boron trichloride j) copper (I) cyanide k) copper (II) cyanide l) lead (II) carbonate m) lead (IV) carbonate