1 Chapter 2 Atoms, Molecules, and Ions 1. Atoms and the atomic theory 2. Components of the atom 3. The periodic table 4. Molecules and Ions 5. Ionic Formulas 6. Names of Compounds

2 Atoms and the Atomic Theory Elements consist of tiny particles called atoms. Atoms retain their identity in reactions. In a compound, atoms combine in fixed ratios of small whole numbers. ( Water = 2 H, 1 O ) Key Figures: Rutherford Discovered nucleus [Gold foil experiment] JJ Thompson

3 Thomson’s discovery of the electron Negatively charged Smaller than proton (1/2000) AMU Electrons

4 Components of Atoms Relative massRelative chargeLocation Proton1+1Nucleus Neutron10Nucleus Electron0.0005Electron cloud

5 Atomic Number, Mass Number Atomic Number = # of protons in nucleus = # of electrons in a neutral atom. (not an ion) Atomic Number is characteristic of a particular element. (all Hydrogen atoms have 1, Helium 2) Mass Number discovery of the nucleus discovery of the nucleus = # of protons + # of neutrons

6 Isotopes: Atoms of the same element with a different mass number. ProtonsNeutronsAtomic Number Nuclear Symbol Mass Number Carbon Carbon-14 68

7 Isotopes of Hydrogen No neutrons 1 neutron2 neutrons deuteriumtritiumprotium

8 Nuclear stability (stable isotopes) Small elements (Up to atomic # 20) the stable proton:neutron ratio = 1:1 Carbon 12, C-12 is a stable carbon isotope. C-16 is unstable. After element 20… Then more neutrons are needed to mute the repulsive force of the protons in the nucleus. For heavy elements Atomic Number =80+ the stable P:N ratio is 1:1.5

9 Groups periods Metals Non Metals

10 Molecules Usually made up of non-metal atoms Held together by covalent bonds

11 Types of formulas Using ethyl (drinking) alcohol as an example: Molecular Formula: C 2 H 6 O Gives # and type of each element Structural Formula: Shows how atoms are bonded Condensed Structural: CH 3 CH 2 OH Gives structural hints

12 Ions Formation of monatomic ions Gain or lose in order to obtain a noble gas electron configuration. Lose electrons: (metals) Na  Na + + e - Gain electrons: (non-metals) F + e -  F –

13 Monatomic ion charges Cations (+) Group 1 +1 Group 2 +2 Aluminum +3 Anions (-) Group Group Nitride-3 Find their locations on the periodic table and label them with their familiar names.

14 Monatomic ions of Transition Metals and POST-transition metals Many are polyvalent i.e. multiple possible charges. Fe 2+, Fe 3+ Cu +, Cu 2+ Pb 2+, Pb 4+ Sn 2+, Sn 4+ Key monovalent ions: Silver Ag + Zinc Zn 2+

15 Polyatomic Ions Group of several atoms acting as an ionic unit. Ex. NO 3 - Nitrate NH 4 + and Hg 2 2+ are the only common polyatomic ions with a positive charge. (Cations)

16 Determine if the following are ionic or molecular KCl NaNO 3 CO 2 PBr 3 CoO CCl 4 Ionic Molecular Ionic Molecular Ionic: metal and non metal (or polyatomic ion) Molecular: 2 or more non metals

17 Formulas of Compounds Ionic compounds: Apply principle of electroneutrality. CationAnionFormulaNet charge Ca 2+ F-F- CaF 2 Al 3+ NO 3 - Al(NO 3 ) 3 Na + H 2 PO 4 - NaH 2 PO 4 Zn 2+ C2H3O2-C2H3O2- Zn(C 2 H 3 O 2 ) 2

18 Ionic Compounds dissolved in water: “electrolytes” Electrolytes can carry a current to complete a circuit. Ionic compounds are electrolytes They may be strong or weak. Molecular compounds are non-electrolytes. They will NOT carry a current to complete a circuit.

19 Names of compounds Ionic: Join together the names of the 2 ions Na + (sodium) Br - (bromide)= NaBr = sodium bromide Polyvalent transition metals include charge in the name Fe 3+ (Iron III) O 2- (Oxide) = Fe 2 O 3 = Iron (III) Oxide Oxo-anions -ate, -ite, per-, hypo-

20 Systematic naming of oxo-anions NitrogenSulfurChlorineBromineIodine Hypo- (least) xx HypochloriteHypo- bromite Hypoiodide -ite (less) NitriteSulfiteChloriteBromiteIodide -ate (more) NitratesulfateChlorateBromateIodate Per- (most) xx perchlorateperbromateperiodate

21 Practice Naming Na 3 N Cu(NO 3 ) 2 LiBrO 2 LiF BeIO 4 Sodium Nitride Copper (II) Nitrate Lithium Bromite Lithium Fluoride Beryllium Periodate

22 Names of compounds Molecular: Use greek prefixes to indicate # of atoms 1 st element: Name + greek # if more than one. 2 nd element: Greek # prefix + “ide” version of element name. CO 2 = Carbon Dioxide

23 Greek Number Prefixes Mono 2. Di 3. Tri 4. Tetra 5. Penta 6. Hexa 7. Hepta 8. Octa 9. Nona 10. deca SF 6 N2O5N2O5 CO Sulfur Dioxide PCl 5 Phosphorus Trichloride H2OH2O

24 Molecular compounds with common names FormulaCommon Name FormulaCommon Name H2OH2O Water PH 3 Phosphine H2O2H2O2 Hydrogen Peroxide AsH 3 Arsine NH 3 Ammonia NO Nitric Oxide N2H4N2H4 Hydrazine (a rocket fuel) N2ON2O Nitrous Oxide (laughing gas) C2H2C2H2 Acetylene (welding gas) CH 4 Methane (natural gas)

25 Acids Compounds with an “H” that ionizes in water. HCl, in water is an electrolyte of H + and Cl - ions. Acid naming Binary (2 types of atoms) use the “–ic” suffix HClHydrochloric acid HIHyrodiodic acid HBrHyrdrobromic acid HFHyrdrofluoric acid

26 Acids Oxo acids: -ate salt = -ic acid NO 3 - is nitrate so HNO 3 is Nitric Acid -ite salt = -ous acid NO 2 - is nitrite so HNO 2 is Nitrous Acid HClOHypoclorous Acid HClO 2 Chlorous Acid HClO 3 Chloric Acid HClO 4 Perchloric Acid