1.2 Early Discoveries Model People have long thinked Radiation Energy Of what is the world made? an What holds it together?
1.2 Early Discoveries Model Radiation Energy
Leucippus and Democritus(. 460-C 370 B.C.) The theory of atomism--The Four Elements Earth Air Fire Water Democritus, atomos(atouos),not divisible
Leucippus and Democritus (c. 460–c. 370 B.C.) The theory of atomism--The Four Elements Earth Air Fire Water Democritus，atomos (ατομος), “not divisible
1803, J. Dalton, suggested that each chemical element was composed of a particular type of atom 1811, A Avogadro, Avogadro's Law 1869 Mendeleev Periodic Table of the elements alkaline earth metals si transitional meta s other metals BC'NOIFNe the molecule as the Na Mg nonmetals noNe gases Al Si P aA smallest particle of K ca sc Cr Mn Fe Co Ni Zn Ga Ge As Se 3r Kr 中,同二中同同时 any substance Rb Sr Y Zr Nb Mo Tc Ru rh pd Ag cd In Sn SbTe molecules Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Ti Pb Bi Po AtRn consisted of ACE I collections of atoms Iat Ca pr Nd pal sm Eu cd Tb D Ho E Tm y u Actinide serics FT Pa U A Fm li d No Is an aton divisible
• 1803, J.Dalton， suggested that each chemical element was composed of a particular type of atom. • 1811, A.Avogadro, Avogadro’s Law. • 1869, Mendeleev， Is an atom divisible ？ the molecule as the smallest particle of any substance molecules, consisted of collections of atoms
Dalton's Atomic theo Dalton(1766-1844): all substances are made of small, indivisible, and fundamental natural units called atoms The law of partial pressure of gases: the pressure of a fixed volume of gases was various symbols like these had proportional to the number been used to represent atoms of of atoms present different elements by Dalton
Dalton’s Atomic Theory Dalton (1766-1844 ): all substances are made of small, indivisible, and fundamental natural units called atoms. The law of partial pressure of gases: the pressure of a fixed volume of gases was proportional to the number of atoms present
Molecules Failure of Dalton's atomic theory 2H+0=2HO 2H+0=H,o(does not agree with volume measured H+0=Ho does not agree with volume measured) Avogadro(1775-1856 ) natural units (for chemical reactions are rather than single atoms 1 voL 0.+2 vol. H>2 voL. HO 2 C0(9)+O2(g) 6.0221367e23 molecules mol-1(physical constant)
Molecules Failure of Dalton’s atomic theory 2 H + O = 2 HO 2 H + O = H2O (does not agree with volume measured) H + O = HO (does not agree with volume measured) Avogadro(1775-1856 ): natural units (for chemical reactions are molecules rather than single atoms. 1 vol. O2 + 2 vol. H2 → 2 vol. H2O 2 CO (g) + O2 (g) Avogadro’s number = 6.0221367e23 molecules mol-1 (physical constant)