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Bettel Plus Chang Chemistry > 3. Nuclear Chemistry > Flashcards

3. Nuclear Chemistry Flashcards

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1
Q

Henri Becquerel (1896)

A

-exposed uranium salts to sunlight and it phosphorescent (umilaw nang slight beh). Placed glowing salts on photographic plate (then coins inbetween salt and plate) ➡️ photographic images of coin
-salts emitting something else other than visible light, akin to xrays

-noble prize shared with marie and pierre curie

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2
Q

Alpha particles

A

-Helium nuclei; two protons and two neutrons (+2)

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3
Q

Beta particles

A

-electrons; (-1)

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4
Q

Gamma rays

A

-high energy electromagnetic radiation; no mass or charge

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5
Q

Cosmic rays

A

Only radiation known to have even higher frequency and energy than gamma rays

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6
Q

Wavelength

A

-distance from one crest to next
-only difference between one form of electromagnetic radiation and another

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7
Q

Frequency, wavelength and energy

A

⬆️Frequency ⬆️Energy ⬇️Wavelength

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8
Q

Photons

A

-smallest unit of packets of electromagnetic radiation

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9
Q

Radioactive

A

-materials that emit radiation(alpha, beta, gamma)
-radioactivity comes from the atomic nucleus

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10
Q

Radioactive isotope

A

-radiation emitting isotope of an element
-some isotopes are radioactive, some are not
(i.e. hydrogen & deuterium (stable); tritium (radioactive))

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11
Q

Nuclear reaction

A

-reaction that changes atomic nuclei of elements

•LIGHTER ELEMENTS: stability occurs when number of protons and neutrons are approximately equal.
•HEAVIER ELEMENTS: stability requires more neutrons than protons

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12
Q

Beta Emission

A

-if a nucleus has more neutrons than it needs, it can stabilize by converting a NEUTRON ➡️ PROTON + ELECTRON
-proton remains but ELECTRON is EMITTED (beta particle)

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13
Q

Transmutation

A

-changing of one element into another
-happens naturally when element gives off beta particle

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14
Q

Alpha emission

A

-mostly occuring for HEAVY ELEMENTS like polonium
-new nucleus always has a mass number four units lower and atomic number two units lower than original nucleus.

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15
Q

Positron Emission

A

-positive electron (0 mass, +1 charge)
-rarer than beta and alpha emission
-nucleus is transmuted to another nucleus with SAME MASS NUMBER but an ATOMIC NUMBER LESS THAN 1.

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16
Q

Gamma emission

A

-often accompanies alpha and beta emissions
-if pure gamma emission, no change in atomic mass and number
-high energy (excited) state ➡️ lower energy (more stable)
-removes excess energy

17
Q

Electron capture

A

-extranuclear electron is captured by the nucleus and it reacts with proton to form neutron

(Ung other four puro decomposition, ito lng yung parang combination)

18
Q

When nucleus gives off radiation…

A

It decays

19
Q

Half life

A

Time it takes for one half of any sample of radioactive material to decay

20
Q

Some radioactive nuclei half life
HYDROGEN-3 (TRITIUM)

A

12.26 yrs

21
Q

Some radioactive nuclei half life
CARBON-14

A

5730 yrs

22
Q

Radioactive dating

A

-technique used to date archeological objects as old as 60,000 yrs
-relies on the principle of carbon-12/ carbon-14 ratio of an organism that it remains constant during lifetime
-when an organism dies, carbon-12 level remains constant since it is stable but carbon-14 decays by beta emission

*Remember!!
Usually around 13.7 disintegrations/min-gramC ang Carbon-14 right after mamatay organism, use this as basis (if di given)

23
Q

Ionizing radiation

A

-alpha, beta, gamma, positron, xrays
-because when they interact with matter, they usually knock out electrons, creating positively charge ions from neutral atoms

24
Q

IONIZING RADIATION CHARACTERISTICS
1. Intensity

A

-Number of particles or photons emerging per unit time
-Common units: Becquerel, Bq (SI; 1 disinteg/sec) and Curie, Ci (3.7x10^10 disinteg/sec; Basis Radium)
-Intensity inverse to distance from radiation source

Measured by:
•Geiger-Muller counter (imagine shape ng resistor hahahaha) and proportional counter containing He/ Ar
-when alpha/ beta/ gamma are emitted, they ionize gas inside the instrument. Instrument detects electric current passing b/w two electrodes.
•Scintillation counter
-have phosphor that emits a unit of light for each particle/ ray that strikes it. Counts/time unit

25
Q

IONIZING RADIATION CHARACTERISTICS
2. Energy

A

-Penetrating power of radiation depends on energy and mass of particles
•Alpha-most massive, most highly charges, least penetrating; stopped by paper, clothing, skin
•Beta-less mass, lower charge, greater penetrating power
•Gamma- have neither mass nor charge, greates penetrating power

26
Q

Activity of radiation

A

Same as intensity of radiation

27
Q

EFFECTS OF RADIATION ON BODY
1. Roentgen, R

A

-measure of energy delivered by radiation source
- 1R = 2.58x10^-4 coulomb of ions/kg
-does not take into account the effect of radiation on tissue and the fact that different tissue absorb different amounts of delivered radiation

28
Q

EFFECTS OF RADIATION ON BODY
2. Rad (Radiation Absorbed Dose)

A

-measure of radiation absorbed from source
-SI unit: Gray (Gy); 1Gy = 100 rad
-ratio between radiation absorbed by tissue and radiation delivered to tissue

29
Q

EFFECTS OF RADIATION ON BODY
3. Rem (Roentgen Equivalent for Man)

A

-measure effect of radiation shen a person aborbs 1 roentgen
-SI unit: Sievert (1Sv=100 rem)
-Tissue damage from 1 rad of absorbed energy depends on type of radiation
-ratio between the tissue damage caused by a rad of radiation and type of radiation

30
Q

Damage on organisms part 1:

A

-Alpha: least penetrative but causes most damage. But since they cannot pass through skin, considered as least harmful

-Gamma: most penetrative so considered as most dangerous and harmful form of radiation.

-Beta: always inbetween alpha and gamma

*For comparison purposes, determine equivalent dose (rem). If different sources, summed up in rems

31
Q

Damage on organisms part 2:

A

Harm may arise in 2 ways:
1. Small doses of radioactivity over a period of years can cause cancer (i.e. tanning overexposure to UV radiation, skin cancer)

  1. Form of radiation strikes egg or sperm cell, causes changes in genes (mutation)
32
Q

Background radiation

A

-Naturally occuring radiation (i.e. cosmic rays, terrestrial radiation like rocks, inside human body like K-40 and Ra-266, Ra in air)

-Mas marami pa nga naturally occuring radiation kesa artificial radiation (normally ah)

33
Q

Nuclear medicine

A

Use of radioactive isotopes as tools for both diagnosis and treatment of diseases

34
Q

Medical imaging

A

-most widely used in nuclear medicine
-create a picture of target tissue
-injects pure radioactive element in target tissue
-method of radiation detection and data passes to computer (intensity and location data)
-i.e. Magnetic Resonance Imaging (MRI)

35
Q

Radioactive Therapy

A

-selective destruction of pathological cells and tissues (remember gamma rays, xrays, etc are deteimental to cells)
-ionizing radiation damage cells, especially those divide rapidly (i.e. radiation in cancer cells)

36
Q

Nuclear Fusion

A

-joining together atomic nuclei to form a nucleus heavier than starting nuclei)
-reactions in sum, hydrogen bomb

37
Q

Transuranium elements

A

-elements with atomic number greater than 92
-artificial; prepared by fusion process; heavy nuclei bombarded with light ones
-short half lives since super unstable

38
Q

Nuclear fission

A

-Enrico Fermi, Otto Hahn, Lisa Meitner
-bombarded uranium-235 with neutrons
-results to fragmentation of large nuclei into smaller pieces
-most important product of decay: atomic energy
-each fission produces 3 neutrons; chain reaction

39
Q

Nuclear power plant

A

-nuclear fission
-energy produced is sent to heat exchangers and used to generate steam, drives turbine, produces electricity
-problem:
•waste disposal, highly radioactive and long half lives
•site not guaranteed to stay dry for centuries; moisture may corrode steel cylinders containing nuclear waste

Bettel Plus Chang Chemistry (19 decks)

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