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Flashcards in Radioactivity Deck (38)
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1

Radioactivity

Spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation

2

Radioisotopes

Radioactive isotope

3

Half life of an element

Time taken for half the nuclei in any given sample to decay

4

Henri Becquerel

-Studying effects of light on uranium salts
-Found uranium salt was giving off some type of radiation

5

Alpha radiation - Nature

Helium nuclei (2 protons + 2 neutrons)

6

Alpha radiation - Charge

+

7

Alpha radiation - Penetrating power

Stopped by paper

8

Alpha radiation - Use/example

Americium-241 used in smoke detectors

9

Beta radiation - Nature

Electrons

10

Beta radiation - Charge

-

11

Beta radiation - Penetrating power

Stopped by aluminium 5mm thick

12

Beta radiation - Use/example

Carbon-14 used to date organic material

13

Gamma radiation - Nature

Waves of high energy

14

Gamma radiation - Charge

None

15

Gamma radiation - Penetrating power

Stopped by several cm of lead

16

Gamma radiation - Use/example

Cobalt-60 used in cancer treatment

17

Used to detect radiation

Geiger-Muller Tube

18

Chemical reactions

-Involved electrons rather than nucleus
-Elements unchanged/(No new element formed)
-No release of nuclear radiation
-Chemical bonds broken + formed

19

Nuclear reactions

-Changes take place in nucleus
-New element formed
-Nuclear radiation released
-No bond breaking or formation

(when writing this, try not to use nuclear radiation and change in nucleus as the two answers, use one of them and then use a diff one from this list)

20

Henri Becquerel

-Exposed uranium salts + photographic plates in sunlight - thought energy from sun being released by crystals created image on the plates
-left in a closed drawer w/ plates, same image formed, no sunlight present

21

Marie Curie

-Marie + Pierre Curie continued Becquerel's work,
-Experimenting pitchblende, realised there must be elements more radioactive than uranium
-Named + discovered polonium + radium

22

Marie Curie nobel prizes

-1903 - Becquerel & Curie & Curie - discovery + research into radioactivity
-1911 - Discovery of radium + polonium, + isolation of radium

23

equations for loss of alpha particle and beta particle

in hardback

24

what changes take place in structure of nuceus of an atom when beta decay occurs?

a neutron changes into a proton and an electron is emitted from nucleus

25

carbon-14 has a half-life of 5730 years

A fragment of yew contained 1.5 x 10¹² carbon-14 atoms. Explain why it must have contained 3.0 x 10¹² carbon-14 atoms 5730 years before the analysis

5730 is the half-life (number of carbon-14 atoms halved in 5730 years)

26

what mass of carbon-14 did the fragment contain 5730 years before the analysis?

(contained 3.0 x 10¹² carbon-14 atoms 5730 years before the analysis)

3.0x10¹² / 6.0 x 10²³ = 5.0 x 10⁻¹² moles of carbon-14 originally

5.0 x 10 ⁻¹² x 14 = 7.0 x 10⁻¹¹ originally

(turn to moles first using avogadro's number. Then, use n = m/mr formula to find mass. Make sure to multiply by 14 here as Mr instead of 12 which is on log table as it specifies that it is carbon-14!!!)

27

pay attention when doing calculations

pay attention to whether they want the answer in atoms or molecules, and whether they give you info in atoms/molecules...

28

properties of beta particles

-negative charge
-negligible mass (mass of electron)
-stopped by aluminium 5mm thick
-moderately ionising

29

caesium-137 has half-life of 30 days, what fraction of this mass remained after 90 days?

1/8

(1/2 x 1/2 x 1/2)

30

explain why the carbon-12 to carbon-14 isotope ration in something changed over 5500 years

carbon-14 decayed (changed to nitrogen)