1. The correct classifications for sea water, distilled water, brass, and helium respectively are (a)compound, element, mixture and compound (b)mixture, element, mixture and compound (c) mixture, compound, mixture and element (d) compound, element, compound and mixture (e) mixture, compound, compound and element All mixtures (indicate correct statement) (a) are heterogeneous in appearance (b) contain different types of molecules (c) contain two or more pure substances (d) can be separated only by chemical means (e) contain more than one physical state

2. DIMENSIONS AND UNITS Need to provide a quantitative means of describing the universe. 7 independent dimensions (physical quantities): 1. Mass (m) quantity of matter in a body 2. Length (l) measurement of distance 3. Time (t) measurement of progress of an event 4. Thermodynamic temperature (T). “The condition of a body which determines the transfer of heat to or from that body”

3. DIMENSIONS AND UNITS 5. Amount of substance (n). “The number of specified entities of a pure substance” 6. Electric current (I): “Rate of transfer of electricity” 7. Luminous intensity (I v ): “Rate of transfer of light energy” Fundamental Property of Dimensions: Two physical quantities having different dimensions cannot be added, subtracted or equated. All other physical quantities can be expressed in terms of these fundamental dimensions e.g. volume of a cube = l x l x l = l 3 velocity = distance/ time = l/t

4. Common S.I. prefixes PrefixNameMeaning Ggiga10 9 Mmega10 6 kkilo10 3 ddeci10 -1 ccenti10 -2 mmilli10 -3  micro10 -6 nnano10 -9 ppico10 -12

5. Derived Units Quantity Definition Derived Unit Area Length x length m 2 Volume Area x length m 3 Density Mass/ unit volume kg m -3 Speed Distance/ unit time m s -1 Acceleration Change in speed/ m s -2 unit time Force Mass x acceleration kg m s -2 (newton, N) Pressure Force/ unit area kg m -1 s -2 (pascal, Pa) Energy Force x distance kg m 2 s -2 (joule, J )

6. Difference between mass and amount of substance:  amount of substance is the number of specified entities (e.g. atoms, molecules, etc.) EntityNumber of entitiesMass (g) Hg6.02 x 10 23 atoms200.59 (= 1 mol) KCl6.02 x 10 23 molecules74.56 (= 1 mol) SO 4 2- 6.02 x 10 23 ions96.06 (=1 mol)

7. Accuracy: measure of how close measurement is to its real value Precision: measure of how close successive measurements are to each other X X X X X X X X X Precise Precise Imprecise & accurate & inaccurate & inaccurate

8. Dimensional analysis: a method of reducing physical quantities to combinations of the 7 basic dimensions Q1. Dimensions of pressure? A. Pressure = Force/Area and we already know the dimensions of force are MLt -2. Thus the dimensions of pressure are MLt -2 /L 2 = ML -1 t -2. Q2. Check the validity of the following equation: PV = nR/T, given units of R to be ML 2 t -2 n -1 T -1. A. Dimensions of L.H.S.: ML -1 t -2. L 3 = ML 2 t -2 Dimensions of R.H.S.: n. ML 2 t -2 n -1 T -1 = ML 2 t -2 T -2 Equating both sides does not cancel all terms, thus equation is invalid.

9. ATOMS AND MOLECULES Atom:smallest particle of an element which can undergo chemical changes in a reaction Molecule: smallest particle of a compound which can exist and still retain the chemical properties of the compound.

10. Structure of the Atom Size:0.1 to 0.5 nanometers (1nm = 1x10 -9 m) Mass:H atom = 1.67x10 -24 g = 1.008 atomic mass units (a.m.u.) C atom = 2x10 -23 g = 12.000 a.m.u. Electrical charge: neutral Composition: contains electrons, protons, and, with the exception of hydrogen, neutrons. ParticleMass (a.m.u.)Charge e- 0.0005 -1 p+ 1.007 +1 n 1.009 0

11. Structure of the Atom Size:0.1 to 0.5 nanometers (1 nm = 1 x 10 -9 m) Nucleus Electron clouds ~ 5 x 10 -15 m ~ 2 x 10 -10 m Nucleus- consists of protons and neutrons

12. “Life-sized” model of the atom “Scaled up” electron mass Electron = 0.0005 a.m.u.Proton = 1.0070 a.m.u. “Model proton” = 65 kg“Model electron” = 32 g “Scaled up” atomic radius Nuclear diameter = 5 x 10 -15 m Atomic diameter = 2 x 10 -10 m “Model nucleus” radius = 1 m “Model atomic” radius = 40 km Q. A speck of carbon contains ca. 10 19 atoms and the diameter of a carbon atom is 1.5 x 10 -10 m. If the circumference of the earth is 40,075 km, how many times around the earth would a line of single carbon atoms extend? A. Length = 10 19 x 1.5 x 10 -10 m = 1.5 x 10 9 m. # times = 1.5 x 10 9 /40075 x 10 3 = 37.4

13. Iron atoms on a copper crystal Xenon atoms on nickel Carbon monoxide molecules on platinum crystal

14. Atomic number:number of protons in an atom. Symbol: Z Atomic mass: mass of an atom in a.m.u. (  number of protons + neutrons in an atom). Symbol: A Atome-p+nZA (a.m.u.) H11011.008 Li33437.016 C666612.000 U929214692238.05

15. Conventional Notation for Chemical Symbols Cl 35 17 - 2 Mass numberNumber and sign of charge Atomic number Number of atoms in entity Examples: He 4 2 OH - CO 3 2-

16. Ions:atoms or molecules which have gained or lost one or more electrons Isotopes: atoms of the same element which have different masses, i.e. different numbers of neutrons Examples of ions:H + H - NO 3 - Examples of isotopes:H 1 1 H 1 2 H 3 1 Hydrogen Deuterium Tritium