Cosmochemistry

Question 1

what is an isotope

Answer 1

same number of protons, different number of neutrons

Question 2

what are “magic” electronic configurations?

Answer 2

a nucleus is most stable when the proton or neutron shells are full and paired, making even numbers more energetically favorable than odd.

Question 3

beta decay

Answer 3

emission of an electron by the nucleus, converts a neutron to a proton and increases Z by one without changing A

Question 4

positron decay

Answer 4

converts a proton to a neutron, reduce Z by one without changing A

Question 5

alpha decay

Answer 5

emission of an alpha particle (2 protons, 2 neutrons), decreases Z by two and A by four

Question 6

quantum numbers

Answer 6

principle quantum number, n: effective volume of an orbital
angular momentum quantum number, l: shape of the region occupied by an electron
magnetic orbital quantum number, ml: orientation of the electron orbital relative to an arbitrary direction
magnetic spin quantum number, ms: describes the positive or negative point relative to an outside magnetic reference

Question 7

pauli exclusion principle

Answer 7

each orbital contains two electrons with opposite spins

Question 8

valence electrons

Answer 8

outermost unfilled shells of electrons surrounding the nucleus

Question 9

ionic bond

Answer 9

between metal and non-metal by the electrostatic attraction between oppositely charged ions

Question 10

cation/anion

Answer 10

donates, becomes positive / accepts, becomes negative

Question 11

covalent bonds

Answer 11

sharing of electrons between atoms, high bond strength

Question 12

metallic bonds

Answer 12

sharing of valence electrons among many atoms in a delocalized manor

Question 13

equilibrium fractionation

Answer 13

partition isotopes without changes in conditions

Question 14

kinetic fractionation

Answer 14

fast, incomplete, or unidirectional processes such as evaporation, diffusion, dissociation reactions, and biological reactions

Question 15

basic process of nucleosynthesis

Answer 15

nucleosynthesis involves the burning of hydrogen and helium to create elements of higher mass.

Question 16

H-R diagram

Answer 16

plot of stellar luminosity vs effective surface temperature. in the main sequence, stars are converting hydrogen to helium in the core

Question 17

r-process

Answer 17

rapid neutron capture such that multiple neutrons can be captured before beta decay occurs

Question 18

s-process

Answer 18

slow neutron capture on a time scale that is slow compared to the rate of beta decay. occurs in the agb stage in low and intermediate mass stars when the H shell is burning outward from the core

Question 19

chondrite classification

Answer 19

type 3= pristine , unaltered
4-7 thermally equilibrated
1-2 aqueously altered

Question 20

matrix material

Answer 20

fine-grained minerals that fill the space between chondrules. high porosity, permeable, especially susceptible to alteration

Question 21

characteristics of aqueous alteration in meteorites

Answer 21

altered matrix material primarily consisting of serpentine, sulfates/carbonates, iron altered to magnetite, no chondrules

Question 22

characteristics of primitive meteorites

Answer 22

glassy chondrule mesostatsis in tact (alt crystallizes mesostasis into feldspar), CaO/FeO concentrations in olivine, chondrule boundaries are sharp, sulfides have low Ni contents, pyroxene is dominantly monoclinic