WEEK 1 Flashcards

1
Q

To maintain precision while solving any mathematical equation involving
numbers…

A

calculations and answers should always be reported in the same number of significant figures as that of the input variables provided

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2
Q

sig fig rules!

A
  1. All non-zero digits are significant
  2. Zeros appearing between any two non-zero digits are significant
  3. Leading zeros are not significant
  4. Trailing zeros in a number containing decimal point are significant
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3
Q

what is a unit?

A

provides measure to the numerical quantity associated with it

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4
Q

what are the fundamental units for distance and time respectively

A

metres (m) and seconds (s)

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5
Q

what are fundamental units?

A

units for physical quantities from which all other units can be generated

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6
Q

SI system fundamental units

A

kilogram (kg), metre (m), candela (cd), second (s), ampere (A), kelvin (K) and mole (mol)

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7
Q

Newton (N)

A

unit for force is composed of combination of fundamental units : kg m s-2

force (N) = mass (kg) x acceleration(ms^-2)

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8
Q

Joules (J)

A

unit for energy is composed of combination of fundamental units : kg m2 s-2

energy (J) = force (kg ms^-2) x distance (m)

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9
Q

Nucleogenesis

A

formation of new nuclei from existing nucleons

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10
Q

Nuclides

A

an atom with a particular mass number and atomic number

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11
Q

Isotope

A

nuclide with the same atomic number but a different mass number

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12
Q

exothermic

A

releases energy into surroundings as heat and radiation

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13
Q

every atom is generated…

A

from the simplest nuclide hydrogen by nuclear reactions

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14
Q

hydrogen burning

A

The star continues to burn H until it exhaust all H atoms, then begins to burn He to for increasingly larger atoms
New element-forming reactions are exothermic until iron
All elements up to iron are produced in stars
When a star has only iron to burn, it consumes energy and implodes, forming a supernova.

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15
Q

The decay constant (k)

A

is characteristic of the particular radioactive nuclide, and does not depend on the amount of sample.

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16
Q

A low activity corresponds to a

A

small decay constant + long half-life

17
Q

A high activity corresponds to a

A

large decay constant + short half-life

18
Q

Radiocarbon dating

A
  1. Measure the *C-14 activity *of the archaeological sample (This is At)
  2. Measure the C-14 activity of an equivalent modern-day sample (this is A0)
  3. Substitute these values into the equation for C-14 age:
    t = 8033 x ln(A0/At)
19
Q

Within a star…

A

clouds of atomic hydrogen are pulled together by gravity and heat as they are compressed. When temp rise high enough, the cloud ignites as a star.

20
Q

balancing nuclear reactions

A

both the mass numbers and atomic numbers must balance

21
Q

Atomic number (Z)

A

= number of protons in the atomic nucleus
* Defines chemical nature (element) of the atom
* Equal to the total charge on the atomic nucleus

22
Q

Mass number (M)

A

= total number of nucleons (protons and neutrons) on the atomic nucleus

23
Q

Atomic mass

A

Atomic mass of an element is the average of the atomic masses and the abundances of each of the naturally-occurring isotopes

24
Q

Hydrogen fusion

A

energy comes from a change in mass, according to E=mc^2

25
Q

Radioactive Atomic Nuclei

A

Undergo spontaneous decay to eventually become a stable nucleus

will have a characteristic mode of decay and half-life

26
Q

Half-life

A

the time required for half of the nuclei in a sample to undergo a decay event

27
Q

The rate of decay…

A

depends on the number of nuclei present

28
Q

activity (A)

A

Activity A of a radioactive sample is a specific measure of the rate of decay, defined as the number of nuclei that disintegrate per second
This unit of activity is the Becquerel
1 Becquerel = 1 disintegration per second
Activity is proportional to the number of nuclei in the sample

29
Q

Specific activity

A

activity per gram of radioactive nuclide

30
Q

Molar activity

A

activity per mole of radioactive nuclide

31
Q

Anion

A

gained electrons so have a negative charge

n more electrons than protons

32
Q

Cation

A

lost electrons so have a positive charge

n fewer electrons than protons