The nature of matter. Chemistry

Transcription

1 The nature of matter Chemistry

2 Take a sample of an unknown material. Divide it into smaller and smaller pieces. Are the properties remaining the same? Apply the process to the following: Milk Water Anti-freeze Lead pipe 14k gold Sugar Water, sugar, protein, fat H2O Propylene (or ethylene)glycol, water Pb, industrially purified Gold, silver alloy Sucrose Substance, Element, Mixture

3 Any characteristic that can be used to describe or identify matter is a property. Intensive properties have values that do not depend upon the amount of matter. Extensive properties have values that depend on the sample size. Properties of Matter

4 Physical properties are characteristics that do not involve a change in the chemical makeup of the sample. A change in phase Chemical properties are characteristics that do involve a change in chemical makeup. Paper burns Physical & Chemical Properties

5 Physical properties are characteristics that do not involve a change in the chemical makeup of the sample. A change in phase Physical Properties

6 Chemical properties are characteristics that do involve a change in chemical makeup. Paper burns Yellow vanadium (VI) is swirled with Jones Reductor and will progressively change color until it reaches the violet vanadium (II). Alternatively, violet vanadium(ii) is oxidized through a series of colors by permanganate to a final yellow color. Chemical properties

7 Density is the ratio of mass (the amount of matter present) to volume (the amount of space that the matter occupies). The ratio of mass to volume of a substance remains a constant for a given set of circumstances. Standard measures of density are reported at 1 atmosphere of pressure and a temperature of 25 degrees Celsius. Density

8 Density is the ratio of mass (the amount of matter present) to volume (the amount of space that the matter occupies). The ratio of mass to volume of a substance remains a constant for a given set of circumstances. Standard measures of density are reported at 1 atmosphere of pressure and a temperature of 25 degrees Celsius. Density

9 Example experiment

10 Earliest recorded history includes information about ten elements (Sb, C, Cu, Au, Fe, Pb, Hg, Ag, S, Sn). These elements occur naturally in native (+0) state. Pb Cu S Photos by Paul Silverman Early known elements

11 Antiquity to 1800 Gray Green Dark Purple Light Purple not shown 112 is named Copernicium 114 is named Flerovium 116 is Livermorium (Lawrence Livermore Laboratories) Antiquity to Middle Ages (14 elements): unrecorded discoveries up into the Middle Ages (Cu, Cr, Fe, Cu, Zn, Ag, Au, C, S, As, Sn, Sb, Pb, Bi) Middle Ages 1800 (22 elements): discoveries during the age of enlightenment (H, Be, Mg, Sr, Ba, Y, Ti, Zr, Mo, Co, Ni, Pt, O, N, W, Mn, Cl, Te, P, U, Al, B) (22 elements): scientific and industrial revolutions (Li, Na, K, Ca, V, Nb, Ta, Ru, Rh, Pd, Cd, Os, Ir, Si, Se, Br, I, La, Ce, Nd, Tb, Er, Th) (26 elements): the age of classifying elements; application of spectrum analysis techniques: Boisbaudran, Bunsen, Crookes, Kirchhoff, and others "hunting emission line signatures" (Rb, Cs, Sc, Ra, Tc, Re, Ga, Ge, In, Tl, Po, He, Ne, Ar, Kr, Xe, Pr, Ac, Sm, Eu, Gd, Dy, Ho, Tm, Yb) (13 elements): development of old quantum theory and quantum mechanics (Fr, Hf, Tc, At, Rn, Pm, Pa, Np, Pu, Am, Cm. Bk, Lu) (16 elements): post Manhattan project; synthesis of atomic numbers 98 and above (colliders, bombardment techniques)(rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Bk, Cf, Es, Fm, Md, No, Lr) Since 2000 (5 elements): recent synthesis

12 The first work to inventory the elements was published in 1789 by French scientist Antoine Lavoisier. A surge in discovery of new elements occurred through 1850 s. The work of John Dalton, 1805, found that elements have a consistent property of atomic mass. He worked to develop the ancient idea of atoms. Observation of reactions and properties of different elements led Johann Dobereiner s hypothesis of triads of related elements in Cl, Br, and I; or Ca, Sr, and Ba. 16 triads were described by Organization of Elements

13 First organizational chart was published by Dmitri Mendeleev in It had seven horizontal rows (periods) and 18 vertical columns (groups). The primary basis for his organization was the atomic mass. Elements in a group have similar chemical properties. There are 90 naturally occurring elements. The other elements have been artificially produced by nuclear chemists in high-energy particle accelerators. First Periodic Table

14 Medeleev left blanks in his table where he predicted there were elements missing based on the patterns he observed in known elements. Mendeleev s Table

15 Other scientists were able to use Medeleev s predictions to look for and find Scandium, Gallium, and Germanium. Elements missing from Mendeleev s Table

16 The periodic table has a total of 32 groups rather than the 18 groups. To fit the chart on a page, the 14 groups that follow lanthanum or actinide are pulled out and displayed below the main chart. IUPAC Periodic Table

17 Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs) are shiny soft metals. All react rapidly (often violently) with water to form highly alkaline (basic) products. Due to the high reactivity, the alkali metals are never found in nature in the pure state, only in combinations with other elements. Group 1A: Alkali metals

18 Group 1A

19 Beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra) are also lustrous, silvery metals. These metals are less reactive than Group I metals and produce alkaline products. Alkaline earth elements are also never found in nature in their pure state. Group 2A: Alkaline earth metals

20 Group 2A

21 Fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) are colorful, corrosive nonmetals. Halogens are found in nature only in combination with other elements, example: table salt (NaCl). Hals means salt in Greek. Astatine is a halogen, but it occurs in tiny amounts with little known about it. Group 7A: Halogens

22 Group 7A or 17

23 Helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) are gases of very low reactivity. He, Ne, and Ar do not combine with any other elements. Kr and Xe combine with very few elements. Group 8A: Noble gases

24 Noble Gases Group 18

25 Metals are the largest category of elements. These are found on the left side of the table. All (except mercury, Hg) are solids at room temperature. Most have silvery shine commonly associated with metals. Most are malleable, not brittle. Metals are good conductors of heat and electricity. Metals

26 Nonmetals (17 in all) are located on the right side of the table. Their appearance can be characterized by lack of silvery lustre. Only five are solids at room temperature, and they are brittle (carbon, phosphorus, sulfur, selenium, and iodine). Bromine is a liquid. All others are gases. Some are brightly colored such as sulfur yellow. All are poor conductors of heat & electricity. Nonmetals

27 Semimetals occur diagonally from boron (B) to astatine (As) at the base of group 7A. Included are silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te). Semimetals have intermediate properties. Silvery in appearance, solid at room temperature, brittle, and poor conductors of heat and electricity. Semimetals

28 Scientific experimentation is performed in a way that can be replicated by others. It is necessary to use common units and nomenclature. International System of Units (SI for the French: Systeme Internationale d Unites) was established by agreement in Metric system has seven fundamental units Measurement Physical Quantity Name of Unit Abbreviation mass kilogram kg length meter m temperature Kelvin K amount of substance mole mol time second s electric current ampere amp luminous intensity candela cd

29 The size of an atom of silicon and the diameter of a star are both measured in meters. SI units are modified by the use of prefixes to bring the unit into scale for the description of scientific observations. Factor Prefix Symbol 1,000,000, E+09giga G 1,000, E+06mega M 1, E+03kilo k E+02hecto h E+01deka da E-01deci da E-02centi c E-03milli m E-06micro E-09nano n E-12pico p Prefixes for Multiples of SI Units

30 For very large or very small numbers, use scientific notation. The exponential format is A x 10 n A is between 1 and 10. The exponent, n, is either a positive or negative integer. Examples: 83,450 = x 10 4 (A x 10 n )(B x 10 m ) = AB x 10 m + n (A x 10 n ) m = A m x 10 m x n Scientific notation

31 Mass is the amount of matter. Matter a generic term of anything with a physical presence. SI unit is kilogram (kg = 2.205US lb). Common prefixes: gram = 10-3 kg milligram = 10-6 kg microgram = 10-9 kg Mass

32 SI unit for length is the meter (m = in). Common prefixes: centimeter = 10-2 m millimeter = 10-3 m micrometer = 10-6 m nanometer = 10-9 m Na atom is 375pm picometer = m Length

33 SI unit for temperature is the Kelvin (omit the word degree) The size of the unit is equal to the degree Celsius ( o C). The unit is equal to one hundredth of the interval between the freezing point of water and the boiling point of water at STP. 0 o C freezing point/ 100 o C boiling point 0 K coldest possible temperature or absolute zero ( co ) Temperature

34 Measure 100mL of water to use in an experiment to produce reliable results. Equipment: Erlenmeyer flask Scale Volumetric flask Beaker Cooking measure Hypothesis: (Frances)If the volumetric flask is used then the results will both more precise and more accurate. Prepare for experiments

35 Results: Weight of 100 ml of Water Total weight Measuring device Tare Weight Trial 1 Trial 2 Trial 3 Average weight Net weight Beaker Volumetric Flask Erhlenmeyer Flask Measuring Cup Conclusion: Write your conclusion based on the data collected, statistical analysis, and the fact that 100 ml of water will have a mass of 100gm at STP. Analysis and conclusions