Chap 2 - Chem 210 / Fall 2009 / Chapter 2.1 – 2.8 Chapter...

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Unformatted text preview: Chem 210 / Fall 2009 / Chapter 2.1 – 2.8 Chapter 2 (Overview) Atoms, Molecules and Ions Modern Modern Atomic Theory 1. Each element is composed of atoms. atoms. 2.3 Atomic Structure 2.5 The Periodic Table 2. Atoms of a given element are identical in 2.7 Ions and Ionic Compounds terms of number of protons; atoms of different protons; 2.8 Naming Ionic Compounds elements have different properties. Online practice goal: achieve >90% in Chap 2. homework 5 and Quiz 5 http://wps.prenhall.com/esm_brown_chemistry_8e/51/13242/3390185.cw/index.html EOC (end-of-chapter problems) (end-of2.57, 2.59, 2.61, 2.64 (textbook page 74) 3. Atoms are not destroyed nor created in chemical changes, only re-arranged. changes, . 4. Compounds are formed when atoms of No No due date - “initial practice” different element combine in definite ratios. ratios. Modern Modern Periodic Table of the Elements The modern periodic table of the elements. Representative group A groups H Li Transition Be B groups period Na Mg K He Ca Sc Ti Zr Period #6 Rb Sr Y Cs Ba La Hf V B C N O F Ne Al Si P S Cl Note locations of metals, metals metalloids & nonmetals Ar Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Ta W Pb Bi Rn Re Os Ir Pt Au Hg Tl Po At Fr Ra Ac Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Inner transition Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr WebElements.com http://www.webelements.com/ Chlorine QuikTime film: rutherfd CrossCross-section of an atom Scandium http://www.webelements.com/ http://www.webelements.c om/scandium/ chlorine/ UM-SJTU JI Page 1 Chem 210 / Fall 2009 / Chapter 2.1 – 2.8 Structure of the atom: A Summary Atomic structure Atoms are made of smaller parts. Name Symbol Charge grams electron e-1 9.11x10-28 proton +1 n 1.67x10-24 1.01 1.01 0 p neutron amu 0.00055 0.00055 1.67x10-24 1.01 Define: atomic mass unit (amu) (amu) • 1 amu = approximately the mass of 1 proton. • 6.022 x 1023 amu = 1mole amu = 1 gram Atoms have a specific arrangement. Nucleus Small, dense, positive charge in the center of an atom that contains protons & neutrons. neutrons Protons discovered by Ernest Rutherford in 1919 Neutrons discovered by J. Chadwick in 1932 Electrons Surround the nucleus, light, diffuse region of negative charge. Atomic Mass approximately equals the mass of protons + neutrons (electron mass negligible)! Isotopes - Atoms of the same element but having different masses All isotopes of the same element have: • the same element symbol. (O = oxygen) symbol • the same number of protons. (O = 8p) protons. Each isotope of the same element has: • Distinct number of neutrons. neutrons – Oxygen-16 = 8n vs. Oxygen-17 = 9n 9n. • Distinct mass. (O-17 is heavier than O-16) Atomic Mass given for an element in the periodic table is the average mass of all its isotopes existing in the natural environment. Natural Isotopes Most elements occur in nature as a mixture of isotopes. Element Number of stable isotopes H C O Fe Sn 2 2 3 4 10 Unstable isotopes are radioactive radioactive. Ions Standard Isotope Symbol protons = lower left corner of element symbol symbol. protons + neutrons = upper left corner Isotopes of hydrogen 1 H 1 Neutron number = 0, Isotopes of carbon 2 H 1 3 H 1 1, 2 13 14 12 C 6C 6C 6 Neutron number = 6, 7, 8 Give the no. of neutrons for each isotope of H and C listed above. UM-SJTU JI An atom, with equal number of electrons and atom, protons, is “neutral” or “no charge”. It can acquire “neutral” a “charge” by losing or gaining electron(s). • Positive ion •cation •Lost e •smaller than atom Na Na+ Cl Cl- • Negative ion •anion •Gained e •larger than atom Page 2 Chem 210 / Fall 2009 / Chapter 2.1 – 2.8 Common simple Ions Some Metals form stable ions of different charges Simple cation = same elemental name. Simple anion has –ide ending. Charge Name Formula H+ Charge Formula Name H- hydride F- hydrogen chloride Ion Formula Systematic Name Cu+1 copper(II) Co+2 Common Name copper(I) Cu+2 Copper fluoride Cl- Element cobalt(II) cuprous cupric Li+ Na+ sodium K+ potassium Br- bromide Co+3 cobalt (III) cobaltic Cs+ cesium I- iodide Fe+2 iron(II) ferrous Ag+ +1 lithium silver Mg2+ +2 Sr2+ O2-2 strontium oxide S2- Fe+3 Mn+3 tin(II) stannous Sn+4 sulfide manganese(III) Sn+2 Manganese iron(III) manganese(II) tin(IV) stannic ferric manganous manganic barium Zn2+ Can you find a pattern in naming these? cadmium Al3+ Tin zinc Cd2+ +3 cobaltous Mn+2 calcium Ba2+ Cobalt Iron magnesium Ca2+ -1 aluminum -3 N 3- nitride Polyatomic ions • A special class of ions containing a group of atoms bonded together. Which of these are among the “COMMON IONS” listed in the table on the back of the textbook? Some polyatomic ions are closely related: NO3- nitra nitrate NO2- nitri nitrite SO42- sulfa sulfate 2- Sulfi Sulfite NH4+ ammonium NO3- nitrate SO3 SO42- sulfate OH- hydroxide O22- peroxide ClO4ClO3ClO2ClO- Which of these are among the “COMMON IONS” listed in the table on the back of the textbook? Ionic Compounds Formed by matching cations & anions in regular array. Cl-1 Na+1 • Net charge = 0! sodium chloride • Crystal structure Conducts electricity when melting or dissolved in water • Ions separate from each other! UM-SJTU JI Can Can you find a pattern? perchlora perchlorate Chlora Chlorate Chlori Chlorite hypochlori hypochlorite Which of these are among the “COMMON IONS” listed in the table on the back of the textbook? Writing formula of ionic compounds Match cation & anion so: Net charge = 0! Net Some simple ions Cations Na+ Fe2+ Anions Cl- O2- SwitchSwitch-over rule: Na+ O2Na2O1 Na2O Al3+ N3Fe2+ Fe3N2 Fe2+ O2Fe2O2 FeO N3- Al3+ O2Al2O3 Page 3 Chem 210 / Fall 2009 / Chapter 2.1 – 2.8 Naming ionic compounds of common ions •Cation first, anion second. •Find names from the “COMMON IONS” “COMMON table on the back of the textbook. Na NaCl sodium chloride PbBr2 Pb Lead (II) bromide KNO3 potassium nitrate Name the following compounds using the common ions table. MgS \______ magnesium sulfide AlCl3 \______ Aluminum chloride Ca(NO2) \______ calcium nitrite CuO CuO \______ Copper (II) oxide (NH4)2CO3 ammonium carbonate COMMON IONS table lists two: copper (I) and copper (II). Which one is in CuO? (II). CuO? http://www.quia.com/mc/65767.html Cations of the same element with different charges: Check the anion! Cu+1 + copper(I) O-2 oxide = Cu2O copper(I) oxide Cu+2 + copper(II) O-2 oxide = CuO copper(II) oxide Naming ionic compounds If there are two or more cations for the metal: • Use reverse switch-over rule. switch• Based on anion charge. Example: Example: Fe Br3 Fe+3 Br -1 iron(III) bromide Examples FeCl2 FeO FeO Fe+2 O -2 Iron (II) oxide Common acids • Formula start with H (or H+1 = cation) with cation) different anions. anions. iron(III) chloride SnBr2 tin(IV) bromide AgCl • Names are based on anions. anions. Acids with anions of –ide ending Named Named hydro…… ic acid Br- UM-SJTU JI Chloride Chloride ⇒ HCl Hydrochloric acid Bromide Bromide ⇒ HBr Hydrobromic acid S-2 Refer to the “COMMON IONS” table on “COMMON the back of the textbook. Cl- Sulfide Sulfide ⇒ H2S I- iodide ⇒HI iodide Hydrosulfuric acid hydroiodic acid Page 4 Chem 210 / Fall 2009 / Chapter 2.1 – 2.8 Acids with anions of –ate ending Named …… Named …… ic acid HClO4 HClO3 HNO3 ClO4- = anion anion = perchlorate perchlorate Perchloric acid anion = ClO3- = Chlorate Chlorate Chloric acid anion = NO3- = nitrate nitrate Acids with anions of –ite ending Named …… Named …… ous acid HClO2 ClO ClO2- = Chlorite Chlorite Chlorous acid HClO ClO hypochlorite ClO- = hypochlorite hypochlorous acid HNO2 NO2- = nitrite NO nitrite nitrous acid Nitric acid Summary of Naming Acids Formula of an acid starts with the “H”: cation = H+ anion = --ide, --ate or --ite anion --ide, --ate --ite Name depends on the anion ---ide anion = hydro---ic acid ---ide hydro---ic HCl = hydrochloric acid ---ate anion = --ic acid ---ate --ic HNO3 = nitric acid ---ite anion = --ous acid ---ite --ous H2SO3 = sulfurous acid Naming Acids HCN look up CN-1 cyanide cyanide ion \________________________ aicd ________________________ HClO2 look up ClO2-1 Chlorite Chlorite ion \__________________________ acid H2CrO4 look up CrO4-2 chromate chromate ion \_______________________ acid HClO4 look up ClO4-1 perchlorate perchlorate ion \________________________________ acid Online Online Games http://101science.com/chemJAVA.htm#Chemistry Various chemistry activities JAVA Applet Links • http://www.quia.com/cm/23398.html Matching the formula and name of a series of cations. •http://www.quia.com/mc/645465.html Matching terms and definitions in Chapter 2. UM-SJTU JI Page 5 ...
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