WEEK 1

Question 1

To maintain precision while solving any mathematical equation involving
numbers…

Answer 1

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

Question 2

sig fig rules!

Answer 2

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

Question 3

what is a unit?

Answer 3

provides measure to the numerical quantity associated with it

Question 4

what are the fundamental units for distance and time respectively

Answer 4

metres (m) and seconds (s)

Question 5

what are fundamental units?

Answer 5

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

Question 6

SI system fundamental units

Answer 6

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

Question 7

Newton (N)

Answer 7

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

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

Question 8

Joules (J)

Answer 8

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

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

Question 9

Nucleogenesis

Answer 9

formation of new nuclei from existing nucleons

Question 10

Nuclides

Answer 10

an atom with a particular mass number and atomic number

Question 11

Isotope

Answer 11

nuclide with the same atomic number but a different mass number

Question 12

exothermic

Answer 12

releases energy into surroundings as heat and radiation

Question 13

every atom is generated…

Answer 13

from the simplest nuclide hydrogen by nuclear reactions

Question 14

hydrogen burning

Answer 14

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.

Question 15

The decay constant (k)

Answer 15

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

Question 16

A low activity corresponds to a

Answer 16

small decay constant + long half-life

Question 17

A high activity corresponds to a

Answer 17

large decay constant + short half-life

Question 18

Radiocarbon dating

Answer 18

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)

Question 19

Within a star…

Answer 19

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.

Question 20

balancing nuclear reactions

Answer 20

both the mass numbers and atomic numbers must balance

Question 21

Atomic number (Z)

Answer 21

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

Question 22

Mass number (M)

Answer 22

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

Question 23

Atomic mass

Answer 23

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

Question 24

Hydrogen fusion

Answer 24

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

Question 25

Radioactive Atomic Nuclei

Answer 25

Undergo **spontaneous decay** to eventually become a *stable* nucleus will have a **characteristic** mode of decay and half-life

Question 26

Half-life

Answer 26

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

Question 27

The rate of decay...

Answer 27

*depends* on the **number** of **nuclei** present

Question 28

activity (A)

Answer 28

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

Question 29

Specific activity

Answer 29

activity per **gram** of radioactive nuclide

Question 30

Molar activity

Answer 30

activity per mole of radioactive nuclide

Question 31

Anion

Answer 31

*gained* **electrons** so have a **negative** charge n more electrons than protons

Question 32

Cation

Answer 32

*lost* **electrons** so have a **positive** charge n fewer electrons than protons