Compounds & Molecules NaCl, salt Buckyball, C 60

Compounds & Molecules COMPOUNDS are a combination of 2 or more elements in definite ratios by mass.COMPOUNDS are a combination of 2 or more elements in definite ratios by mass. The character of each element is lost when forming a compound.The character of each element is lost when forming a compound. MOLECULES are the smallest unit of a compound that retains the characteristics of the compound.MOLECULES are the smallest unit of a compound that retains the characteristics of the compound.

ELEMENTS THAT EXIST AS DIATOMIC MOLECULES

ELEMENTS THAT EXIST AS MOLECULES Allotropes of C

ELEMENTS THAT EXIST AS POLYATOMIC MOLECULES White P 4 and polymeric red phosphorus S 8 sulfur molecules

Molecular Compounds Compounds without Ions CH 4 methane CO 2 Carbon dioxide BCl 3 boron trichloride

MOLECULAR FORMULAS Formula for glycine is C 2 H 5 NO 2Formula for glycine is C 2 H 5 NO 2 In one molecule there areIn one molecule there are –2 C atoms –5 H atoms –1 N atom –2 O atoms

STRUCTUAL FORMULAS Can also write glycine formula as –H 2 NCH 2 COOH to show atom ordering structural formulaor in the form of a structural formula

MOLECULAR MODELING Ball & stick Space-filling Drawing of glycine

Naming Elements & Compounds Chapter 2 & 3: Chemical Equations Handbook BCl 3 boron trichloride CO 2 Carbon dioxide molecules are formed from two or more nonmetals. Ionic compounds have a cation and anion: generally involve a metal and nonmetal, NaCl ammonium chloride, NHCl ammonium chloride, NH 4 Cl

IONS AND IONIC COMPOUNDS IONS are atoms or groups of atoms with a positive or negative charge.IONS are atoms or groups of atoms with a positive or negative charge. Taking away an electron from an atom gives a CATION with a positive chargeTaking away an electron from an atom gives a CATION with a positive charge Adding an electron to an atom gives an ANION with a negative charge.Adding an electron to an atom gives an ANION with a negative charge.

Forming Cations & Anions A CATION forms when an atom loses one or more electrons. An ANION forms when an atom gains one or more electrons Mg --> Mg e- F + e- --> F -

CATION + ANION ---> COMPOUND COMPOUND CATION + ANION ---> COMPOUND COMPOUND Are NEUTRAL. Compounds have EQUAL number of + EQUAL number of + and - charges. Are NEUTRAL. Compounds have EQUAL number of + EQUAL number of + and - charges. COMPOUNDS FORMED FROM IONS Na + + Cl - --> NaCl

IONIC COMPOUNDS NH 4 + Cl - ammonium chloride, NH 4 Cl

Properties of Ionic Compounds Forming NaCl from Na and Cl 2 A metal atom can transfer an electron to a nonmetal.A metal atom can transfer an electron to a nonmetal. The resulting cation and anion are attracted to each other by electrostatic forces.The resulting cation and anion are attracted to each other by electrostatic forces.

Electrostatic Forces The oppositely charged ions in ionic compounds are attracted to one another by ELECTROSTATIC FORCES. These forces are governed by COULOMB’S LAW.

Electrostatic Forces COULOMB’S LAW Direct relationship between charge and force: charges increase, the force increases. Inverse relationship between distance between ions and force: increase distance, decrease force. increase distance, decrease force.

Importance of Coulomb’s Law NaCl, Na + and Cl -, m.p. 804 o C MgO, Mg 2+ and O 2- m.p o C

PREDICTING ION CHARGES In general metals (Mg) lose electrons ---> cationsmetals (Mg) lose electrons ---> cations nonmetals (F) gain electrons ---> anionsnonmetals (F) gain electrons ---> anions

METALS M ---> n e- + M n+ where n = periodic group Na + sodium ion Mg 2+ magnesium ion Al 3+ aluminum ion Transition metals --> M 2+ or M 3+ are common Fe 2+ iron(II) ion Fe 3+ iron(III) ion

NONMETALSNONMETALS NONMETAL + n e > X n- where n = 8 - Group no. C 4-,carbide N 3-, nitride O 2-, oxide S 2-, sulfide F -, fluoride Cl -, chloride Group 7AGroup 6A Group 4A Group 5A Br -, bromide I -, iodide

Charges on Common Ions By losing or gaining e-, atom has same number of e-’s as nearest Group 8A atom.

Predicting Charges on Monatomic Ions

Binary Ionic Compounds Mn 2+ + O > MnO manganese (II) oxide Al 3+ + S > Al 2 S 3 aluminum sulfide Sn 4+ + Cl > SnCl 4 Tin (IV) chloride or Stannic chloride calcium fluoride Ca F - ---> CaF 2

Practice Name & Formulas Ultimate Equation Handbook Only the binary compounds Exercise 2-1 pg. 10 Exercise 3-2 pg 17 Homework: Worksheets pgs 23-28

POLYATOMIC IONS Groups of atoms with a charge. MEMORIZE the names and formulas in Table 3.1, page 89.

Polyatomic Ions NH 4 + ammonium ion One of the few common polyatomic cations

Polyatomic Ions HNO 3 nitric acid NO 3 - nitrate ion

Polyatomic Ions CO 3 2- carbonate ion HCO 3 - bicarbonate ion hydrogen carbonate

PO 4 3- phosphate ion CH 3 CO 2 - acetate ion Polyatomic Ions

SO 4 2- sulfate ion SO 3 2- sulfite ion Polyatomic Ions

NO 3 - nitrate ion NO 2 - nitrite ion Polyatomic Ions

“ates” Worksheet pg #22

Practice Name & Formulas Ultimate Equation Handbook Add the polyatomic compounds Exercise 2-1 pg. 10 Exercise 3-2 pg 17 Exercise 4-1 pg 20 Exercise 4-3 pg 21 Homework: Worksheets pgs –poly Pgs 29-33

Molecular & Ionic Compounds Heme NaCl