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Z = proton number = atomic number N = neutron number A = mass number (Z+N) Atomic mass of nuclide = (rest mass – binding energy) relative to 1/12.

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Presentation on theme: "Z = proton number = atomic number N = neutron number A = mass number (Z+N) Atomic mass of nuclide = (rest mass – binding energy) relative to 1/12."— Presentation transcript:

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4 Z = proton number = atomic number N = neutron number A = mass number (Z+N) Atomic mass of nuclide = (rest mass – binding energy) relative to 1/12 mass of 12 C atom, measured in atomic mass units – amu’s (must be looked up) Atomic weight of element = sum of the masses of the isotopes of that element times their atomic abundance (found in most textbooks)

5 Pauli exclusion principle Hunds rule Electrons & orbitals

6 Aufbau principle

7 Charges Ionization potential More stable: Filled shells Filled subshells Filled and half filled orbital types

8 Ionization potential = energy required to remove an electron Electron affinity = energy given off when adding an electron to a neutral atom S and p x, p y and p z orbitals

9 Electronegativity = (sum of IP & EA) x constant Electronegativity difference of 1.7 = 50% ionic character

10 Electronegativity differences : Examples: >2.1 - high ionic character (electrons exchanged)halite, Mg-O, Ca-O, K-O, Na-O bonds in silicates, carbonates and other oxidiized complex anions metal and non-metal - weak ionic characterFe-O, also Ti, V, Cr-O bonds in silicates nonmetals - polar covalent bondRare (except for Si-O) polar covalent bondFe-S, also Ni, Cu, Pb, Hg bonds in sulfides also C-O, S-O, Si-O, P-O, N-O in complex ions <0.5 - nonmetals - non -polar covalent bond Graphite, sulfur, realgar, orpiment, <0.5 - high electronegativity metalsGold, silver, platinum group, metallic bonding

11 Goldschmidt’s classification

12 Covalent bond character – hybrid orbitals form

13 Ionic bonding produces close- packed structures. There is a balance between attraction of oppositely charged ions and repulsion by outer electrons on both. Radius ratio = radius of cation/anion in a bond. This determines the coordination number

14 Ionic Radii

15 Crystal field splitting – orbitals change energy in a surrounding crystal lattice Leads to high spin (larger radius) and low spin electron configurations Produces color in minerals (example Fe +3 with 5 d electrons)

16 Common silicates and oxides: CN = 4 (Si, Al) CN = 6 (Mg, Fe) CN = 8 (Ca, Na) In mantle: olivine, orthopyroxene, clinopyroxene, spinel, garnet

17 In the earth, abundant elements form minerals with specific coordination polyhedra or sites. Minor elements either substitute or form rare minerals. The ability to substitute is controlled by:1) radius; 2) charge (valence); 3) electronegativity (bonding behavior) Contours are enrichment in crust/mantle

18 Mineral/melt partition or distribution coefficients Ionic radius K D = concentration in mineral concentration in liquid Eu has two valences: Eu +2 and Eu +3

19 You can calculate partition coefficients for any element in any mineral from the radius of the mineral site and elastic properties of the mineral.

20 Continental crust is complement to depleted mantle Bulk partition coefficient = sum of each mineral Kd X the abundance of the mineral during melting or crystallization Bulk Kd > 1 – element is compatible, Bulk Kd < 1 - incompatible

21 Increasing compatibility for mantle melting

22 Kinds of incompatible trace elements: Rb, K, Ba, Sr = large ion lithophile elements (LILE) Th, U, Zr, Hf, Nb = high field strength elements (HFSE) (Field strength = charge/ionic radius)

23 Water and Aqueous solutions

24 Ionic potential = field strength = charge/ radius

25 Residence time = Total mass of element in reservoir (oceans)/influx Grams/(grams/year)

26 Basalts from subduction zones – island arc basalt Fluid mobile elements (FME) = Rb, Ba, K, Pb, Sr Fluid immobile elements = Nb,Ta, Zr (Hf), Ti

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