Chapter 12: Nuclear Phenomena Flashcards Preview

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Flashcards in Chapter 12: Nuclear Phenomena Deck (26):
1

Atomic number (Z):

always an integer and is equal to the number of protons in the nucleus

2

Mass number (A):

equal to the total number of nucleons (protons and neutrons) in a nucleus.

3

Isotopic notation:

immediately left to the chemical symbol, the mass number and atomic number can be read top to bottom, respectively. 

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4

Isotopes:

atoms of the same element that have different mass numbers; same number of protons, different number of neutrons;

Isotopes generally exhibit the same chemical properties

5

Radionuclide:

generic term used to refer to any radioactive isotope, especially those used in nuclear medicine

6

The atomic mass of an atom is simply equal to:

its mass number (A)

7

Atomic weight:

the mass in grams of one mole of atoms of a given element. Expressed g/mol

8

Nuclear binding energy is:

the amount of energy that is released when nucleons (protons and neutrons) bind together through strong nuclear force

9

Mass defect is:

the difference between the mass of the unbound constituents and the mass of the bound constituents in the nucleus

10

Unbound constituents in the nucleus have:

more energy and more mass than the bound constituents

11

Mass defect is the amount of mass converted to energy through:

the nuclear reactions of fusion or fission

12

Fusion:

occurs when small nuclei combine into larger nuclei

13

Fission:

occurs when a large nucleus splits into smaller nuclei; rarely spontaneous; when a nucleus absorbs a low energy neutron, a chain reaction can occur

14

Energy is released in both fusion and fission because:

the nuclei formed in both processes are more stable than the starting nuclei

15

Alpha decay is:

Loss of a 4-He nucleus (2 protons and 2 neutrons). Mass number decreases by 4 and atomic number decreases by 2.

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16

Beta decay is:

Loss of an electron (e- or β-). Emitted when a neutron in the nucleus decays into a proton and an antineutrino (β-). A neutron is lost and a proton takes its place. Mass number remains the same and atomic number increases by one.

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17

Positron decay is:

when a proton splits into a positron (β+) and a neutron. A proton is lost and the mass number remains the same.

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18

Gamma decay is :

the emission of a gamma photon. The energy of the parent nucleus is lowered, but the mass and atomic number remain the same.

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19

Electron capture is:

When a radionuclide captures an inner electron that combines with a proton to form a neutron. Atomic number is one less and mass number remains the same.

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20

Half-life is:

the amount of time required for half of a sample of radioactive nuclei to decay

T1/2 = 0.693/λ

21

The rate at which radioactive nuclei decay is proportional to:

the number of nuclei that remain

22

The more binding energy per nucleon released, the more:

stable the nucleus

23

Equation for exponential decay:

n = noe-λt

24

Equation to determine the mass lost as binding energy in a nucleus:

E = mc2

where m is the mass of c is the speed of light

25

When protons and neutrons come together to form the nucleus, they are attracted to each other by:

the strong nuclear force

26

The most stable atom according to binding energy per nucleon is:

iron

in general, intermediate-sized nuclei are more stable than large and small nuclei