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Atoms, Molecules and Ions

Atoms, Molecules and Ions. Atomic Theory of Matter. John Dalton. 1806. 1. Matter consists of indivisible atoms. All atoms of a given element have identical properties. Different elements have atoms that differ in mass. 4. Atoms are indestructible and chemical

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Atoms, Molecules and Ions

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  1. Atoms, Molecules and Ions Atomic Theory of Matter John Dalton 1806 1. Matter consists of indivisible atoms • All atoms of a given element • have identical properties • Different elements have atoms that • differ in mass 4. Atoms are indestructible and chemical reactions are a rearrangement of atoms 5. Compounds contain a definite and small number of atoms

  2. 1. Matter consists of indivisible atoms • electrons • protons • neutrons subatomic particles electrons -1.60 x 10-19 C charge = = -1 = 9.1 x 10-31 kg mass protons charge = +1 mass = 1.673 x 10-27 kg neutrons charge = 0 mass = 1.675 x 10-27 kg

  3. 1. Matter consists of indivisible atoms nucleus = protons + neutrons move around the nucleus electrons electron “cloud” = volume of atom average diameter of atom 10-10 m = ångström (Å)

  4. 2. All atoms of a given element have identical properties X A Z ? not exactly atoms of an element = same number of protons = Z atomic number Z = 6 = C carbon 6C 6 e- Z = 30 = Zn zinc 30Zn 30 e- # protons = # e- elements neutral different # neutrons elements proton + neutron = A = mass number

  5. 2. All atoms of a given element have identical properties X A Z isotopes 7 nuclides of C element can have Z = 6 carbon 6C 12 most abundant 6 neutrons Carbon-14 dating C 6 14 6 protons + 8 neutrons What is the symbol for a nuclide that contains 22 neutrons and 18 protons? Ar 40 18

  6. 4. Atoms are indestructible and chemical reactions are a rearrangement of atoms reactions valence electrons valence e- = Group number 1 8 2 3 4 5 6 7

  7. 1 8 2 3 4 5 6 7 elements arranged by atomic number column group chemical properties row period

  8. ( protons, e-) Na ( protons, e-) 11 Noble gases unreactive 8 valence electrons (He 2 valence e-) monatomic gases Alkali metals soft solids very, very reactive 1 valence electron lose 1 electron 11 11 Na 10 + cation

  9. Alkaline earth metals solids reactive lose 2 electrons 2 valence electrons Sr Sr2+ conduct heat, electricity solids (Hg) losee- non-metals metals

  10. 4 5 6 7 3 = metalloids B5 C 6 N 7 O 8 F 9 Si 14 P 15 S 16 Cl17 As33 Se34 Br35 Te52 I 53 At85 Cl ( protons, e-) 17 Non-metals poor conductors solids, liquids, gases X2 Group 7 halogens very reactive 7 valence electrons gain 1 electron Cl ( protons, e-) 17 17 18 - anion non-metals gain electrons

  11. H ( proton, e-) 1 H ( proton, e-) H ( proton, e-) 1 1 1 doesn’t fit anywhere H 1 lose e- H ( proton, e-) 1 1 0 + gain e- proton 2 - hydride

  12. 5. Compounds contain a definite and small number of atoms Ionic solids cation + anion - + non-metal metal chlorine sodium + sodium chloride NaCl Na Cl + - 801o C oxygen lithium + lithium oxide Li O Li O 2 + 2- > 1700oC nitrogen magnesium + magnesium nitride Mg N Mg N 2 3 2+ 3- (ion-ion) strong interactions high melting points

  13. O 2- Transition metals Ag+ Zn2+ Cd2+ Al3+ more than 1 form except manganese oxygen + aluminum + sulfur Mn1+ Mn2+ Mn3+ Mn4+ Al S 3+ 2- AlS 2 3 Mn3+ Mn2O3 aluminumsulfide Mn4+ MnO2 O2- manganese (III) oxide manganese (IV) oxide

  14. Covalent compounds non-metal non-metal + share valence electrons = chemical bonds carbon + chlorine • mono • di • tri • tetra • penta • hexa • hepta • octa Cl C - 4+ CCl4 chloride carbon tetra nitrogen + oxygen N O ? 2- nitrogen monoxide NO 2+ nitrogen dioxide NO2 4+ dinitrogen N2O4 tetroxide 4+

  15. Covalent compounds N nitrogen ammonia H NH3 trihydride 3+ 1- monoxide dihydrogen water H O H2O 1+ 2- weak forces low m.p. 0.0oC Table 2.5 p. 62 Polyatomic ions ammonium ClO3- chlorate NH4+ OH- hydroxide MnO4- permanganate NO3- nitrate CrO42- chromate SO42- sulfate CO32- carbonate PO43- phosphate

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