Definitions & Decay

Question 1

Stable isotopes

Answer 1

Reference to light elements.
Light elements have a large percentage difference in the masses of their isotopes. Behave differently by various physical & chemical processes.

Question 2

Examples of stable isotopes

Answer 2

H, C, N, O, S and Cl, Li, B, Si

Question 3

How to measure isotopes in water

Answer 3

Waters are equilibriums with CO2 and fed into mass spec

Question 4

Measuring isotopes in carbonates

Answer 4

Carbonate mineral is converted to CO2 gas

Question 5

Reference standard for oxygen

Answer 5

Waters reference VSMOW
Waters depleted in 18O reference SLAP
Oxygen in carbonates reference VSMOW or VPDB

Question 6

VSMOW

Answer 6

Vienna standard mean ocean water

Question 7

SLAP

Answer 7

Standard light Antarctic precipitation

Question 8

VPDB

Answer 8

Vienna pee dee belemnite

Question 9

Reference standard for hydrogen

Answer 9

Rations are referred to VSMOW

Question 10

Reference standard for Carbon

Answer 10

Referenced to VPDB

Question 11

Reference of S

Answer 11

To CDT (canon diablo troilite)

Question 12

Reference N, NO2 and He

Answer 12

Atmospheric nitrogen

Question 13

Reference chlorine

Answer 13

SMOC (standard mean ocean chloride)

Question 14

3 ways for thermodynamic fractionation

Answer 14

1) equilibrium physiochemical exchange
2) non- equilibrium reactions (kinetic controlled)
3) molecular diffusion

Question 15

Molecules with a ______ isotope can diffuse out of a system more rapid than a molecule with a _____ isotope

Answer 15

Light
Heavy

Question 16

Heavy isotopes react ______ when forming a bond and breaking a molecule that doesn’t want to be broken

Answer 16

Faster

Question 17

Disequilibrium factor

Answer 17

The heavier isotope forms the stronger bonds and has a greater tendency to react rapidly & form a new compound.

Question 18

If bonds are too strong equilibrium _____ occur

Answer 18

cannot

Question 19

If the new compound is physically removed from the system ______ can occur

Answer 19

fractionation

Question 20

Half-life

Answer 20

Time it takes for half of the atoms to decay into a new isotope

Question 21

Beta Decay

Answer 21

Really common. Transformation of a neutron into a proton plus an electron.
Atomic number increases by 1, neutrons decrease by 1

Question 22

Positron Decay

Answer 22

A proton changes into a neutron releasing a positively charged electron and energy.
Atomic number decreases and neutrons increase

Question 23

Electron Capture

Answer 23

An electron is captured from the electron cloud. A proton is turned into a neutron because of electron absorption.
Atomic number decreases and neutrons increase

Question 24

Alpha decay

Answer 24

Common mode of decay. Alpha particles consist of 2 protons and 2 neutrons.

Atomic number decreases by 2 neutrons decrease by 2 and mass number decreases by 4

Question 25

Nuclear fission

Answer 25

Nucleus breaks into two unequal parts, emitting alpha particles, neutrons and large amounts of electromagnetic radiation. Fission is NOT decay

Question 26

What most often undergoes nuclear fission?

Answer 26

235 U 92

Question 27

Branched decay

Answer 27

Isotopes decay to two different isotopes. COmmon especially in U and Th

Question 28

Some isotopes undergo decay to ______ isotopes. Decay continues until a _____ isotope is produced.

Answer 28

Unstable Stable

Question 29

Decay of parent into a daughter

Answer 29

Number of atoms is halved. The number of daughter isotope atoms increases by the number of parents the decay,

Question 30

Stromatolites

Answer 30

Centermentary structures created by cyanobacteria

Question 31

crossbedding vs. rip up clasts

Answer 31

Both stromatolites Cross - Typical of shallow tidal water Rip up - Typical of shallow storm waters

Question 32

Serendipity

Answer 32

Rocks taken to 500 degrees but local fluids prevent tremolite crystallization and fossil destruction.