OpenLLM-France/wikimedia huggingface dataset:
# World of Dinosaurs/Methods

How do scientists determine what's a bone and what's a rock? The answer lies within the tongue. Due to bone's porosity, it will stick to your tongue.
# World of Dinosaurs/Mineralogy/Feldspars

Feldspar is made of oxygen, silica, and lots of little cations, like calcium, potassium, etc.
Here is a 3D model of a feldspar. This is another example of a slightly different feldspar.

## Attributes

* Feldspar is opaque with a greasy luster.
* One chemical form is a dusty pink.
* The other form is a dirty white.
* It forms as a trapezoid prisms - like cubes, but with a little bit of a lean.
** You can find big chunks - the size of a golf ball or racketball - while hiking in the mountains.
** Usually we see feldspar as the opaque bits of granite, as the opaque grains in sand, or as the dull and orange-y bits in sandstone.
* Feldspar is hard to scratch, hard to dissolve, and will break if a hammer hits it.
** It has a mix of ionic and covalent bonds.
** Dissolving or breaking feldspar is easier than dissolving or breaking quartz, but harder than mica.
* Broken feldspar will keep making smaller and smaller trapezoid prisms
** This is because there are lines of weakness formed by ionic bonds.
** The weak planes break, leaving crisp sides to the little baby trapezoids.
* Feldspar chunks can get sloppy edges.
** Chemical weathering can attack the edges of feldspar chunks.
** It's easier to dissolve feldspar than quartz.
** Tiny sand grains made of feldspar mineral might look a little bit more rounded off than their quartz neighbors.

## Where to find Feldspar and how it's formed

Feldspar forms naturally without help from life in igneous rocks.
* It can form in magma that cools slowly, deep within Earth's crust.
** Examples include granite and diorite.
** Feldspar crystals are the opaque sections that look like white chocolate or have a pink hue.

## Importance in sedimentary rocks

Sandy beaches in California, Oregon, and Washington include lots of quartz grains, and often an equal number of feldspar chunks.
Feldspar forms by:
* Weathering the original rock where the feldspar formed, possibly an igneous granite;
* Transporting and breaking the feldspar in a river;
* Further breaking the feldspar as they shift at a beach.
Feldspar CAN get destroyed by enough weathering and erosion.
* Extremely "mature" sand will have no feldspar, because it's been weathering and eroding for so long.
* You can tell how "mature" a sand, or the grains in a sandstone, are by:
** The minerals present
** How rounded-off the grains of feldspar and quartz look.
*** More angular chunks means fresher grains, less travel, etc.
*** More rounded-off means longer time or space traveled.
Sand can make SANDSTONE in the right conditions
# World of Dinosaurs/Horns vs Antlers

Horns are bone coated in a protein. They stay on the animal's skull and continue to grow throughout the animal's life.
Examples include:
* Bison
* Cows
* Giraffe
* Utahceratops
* Pachycephalosaurus
Antlers are bones, and they can come off the animal's skull in many cases. In many cases they regrow yearly.
Examples include:
* Moose
* Deer
* Elk
# World of Dinosaurs/Magpie
## Name

Magpie
# A-level Chemistry/OCR (Salters)/Alkenes

ALKENES Alkenes are unsaturated hydrocarbons containing at least one double bond. What should be the general formula of alkenes? If there is one double bond between two carbon atoms in alkenes, they must possess two hydrogen atoms less than alkanes. Hence, general formula for alkenes is CnH2n. Alkenes are also known as olefins (oil forming) since the first member, ethylene or ethene (C2H4) was found to form an oily liquid on reaction with chlorine. Structure of Double Bond Carbon-carbon double bond in alkenes consists of one strong sigma (σ) bond (bond enthalpy about 397 kJ mol–1) due to head-on overlapping of sp2 hybridised orbitals and one weak pi (π) bond (bond enthalpy about 284 kJ mol–1) obtained by lateral or sideways overlapping of the two 2p orbitals of the two carbon atoms. The double bond is shorter in bond length (134 pm) than the C–C single bond (154 pm). You have already read that the pi (π) bond is a weaker bond due to poor sideways overlapping between the two 2p orbitals. Thus, the presence of the pi (π) bond makes alkenes behave as sources of loosely held mobile electrons. Therefore, alkenes are easily attacked by reagents or compounds which are in search of electrons. Such reagents are called electrophilic reagents. The presence of weaker π-bond makes alkenes unstable molecules in comparison to alkanes and thus, alkenes can be changed into single bond compounds by combining with the electrophilic reagents. Strength of the double bond (bond enthalpy, 681 kJ mol–1) is greater than that of a carbon-carbon single bond in ethane (bond enthalpy, 348 kJ mol–1).
# A-level Chemistry/OCR (Salters)/Alcohols
## Alkan-1-ols

| Carbons | Alcohol | Condensed formula | Skeletal formula | 3D model | mp | bp |
| 0 | water* | HOH | N/A | | 0 °C | 100 °C |
| 1 | methanol | CH$_3$OH | | | –97 °C | 65 °C |
| 2 | ethanol | C$_2$H$_5$OH | | | −114 °C | 78 °C |
| 3 | propan-1-ol | C$_3$H$_7$OH | | | −127 °C | 97 °C |
| 4 | butan-1-ol | C$_4$H$_9$OH | | | −90 °C | 118 °C |
| n | alkan-1-ol | C$_n$H$_{2n+1}$OH | N/A | N/A | N/A | N/A |
* water is not an alcohol, but is included in this table to show how alcohols can be considered as being derived from water by replacing a hydrogen atom with an alkyl group
# A-level Chemistry/OCR/Rings, Polymers and Analysis/Rings, Acids and Amines/Amines

The following image summarises the reactions covered in Module 1 of F324. You will need to know all of these for the exam.
# A-level Chemistry/OCR (Salters)

This Wikibook is about A-level Chemistry, designed to follow the OCR (Salters) syllabus, but is not endorsed by OCR. It will hopefully be useful as a revision guide or for alternative explanations to the ones in your textbook or from your tutor.

## AS Units
### Chemistry for Life (2850)

* The Elements of Life (April 13th, 2009)
* Developing Fuels (April 13th, 2009)

### Chemistry of Natural Resources (2848)

* Elements from the Sea (April 13th, 2009)
* The Atmosphere (April 13th, 2009)
* The Polymer Revolution (April 13th, 2009)

### Skills for Chemistry (2852)

* Open-Book Paper (April 13th, 2009)
* Experimental Skills (April 13th, 2009)

## A2 Units
### Chemistry of Materials (2849)

* What's in a Medicine? (April 13th, 2009)
* Designer Polymers (April 13th, 2009)
* Engineering Proteins (April 13th, 2009)
* The Steel Story (April 13th, 2009)

### Chemistry by Design (2854)

* Aspects of Agriculture (April 13th, 2009)
* Colour by Design (April 13th, 2009)
* The Oceans (April 13th, 2009)
* Medicines by Design (April 13th, 2009)
* Visiting the Chemical Industry (April 13th, 2009)

### Individual Investigation (2855)
## The Chemistry

* Alkenes
* Alkynes
* Amino acids (April 13th, 2009)
* Atomic orbitals (April 13th, 2009)
* Born-Haber cycles (April 13th, 2009)
* Buffer solutions (April 13th, 2009)
* Complexes (April 13th, 2009)
* Electronic configurations (April 13th, 2009)
* Hydrogen (April 13th, 2009)
* Isomerism (April 13th, 2009)
* Molecular geometry (April 13th, 2009)
* Reactions of arenes (April 13th, 2009)
* Spectroscopy (April 13th, 2009)
* Vacuum filtration (April 13th, 2009)
* Weak acids (April 13th, 2009)
* Yield (April 13th, 2009)

## Goodies

* Chemical Ideas table of contents (April 13th, 2009)
* Table of functional groups met during the course (April 13th, 2009)
* Table of substances met during the course (April 13th, 2009)
* Table of constants met during the course (April 13th, 2009)
* Table of physical quantities met during the course (April 13th, 2009)
* Periodic table of the elements (April 13th, 2009)

## Index

* Salters Advanced Chemistry Wikibook index (April 13th, 2009)

## External links

* University of York course website
* OCR course website
* OCR (Salters) Advanced GCE in Chemistry — Complete Specification, Third Edition
* Organic reactions revision flashcards
# A-level Chemistry/OCR (Salters)/Alkynes

ALKYNES Like alkenes, alkynes are also unsaturated hydrocarbons. They contain at least one triple bond between two carbon atoms. The number of hydrogen atoms is still less in alkynes as compared to alkenes or alkanes. Their general formula is CnH2n–2. The first stable member of alkyne series is ethyne which is popularly known as acetylene. Acetylene is used for arc welding purposes in the form of oxyacetylene flame obtained by mixing acetylene with oxygen gas. Alkynes are starting materials for a large number of organic compounds. Hence, it is interesting to study this class of organic compounds.
Structure of Triple Bond Ethyne is the simplest molecule of alkyne series. Structure of ethyne is shown in Fig. 13.6.
Each carbon atom of ethyne has two sp hybridised orbitals. Carbon-carbon sigma (σ) bond is obtained by the head-on overlapping of the two sp hybridised orbitals of the two carbon atoms. The remaining sp hybridised orbital of each carbon atom undergoes overlapping along the internuclear axis with the 1s orbital of each of the two hydrogen atoms forming two C-H sigma bonds. H-C-C bond angle is of 180°. Each carbon has two unhybridised p orbitals which are perpendicular to each other as well as to the plane of the C-C sigma bond. The 2p orbitals of one carbon atom are parallel to the 2p orbitals of the other carbon atom, which undergo lateral or sideways overlapping to form two pi (π) bonds between two carbon atoms. Thus ethyne molecule consists of one C–C σ bond, two C–H σ bonds and two C–C π bonds. The strength of C≡C bond (bond enthalpy 823 kJ mol-1) is more than those of C=C bond (bond enthalpy 681 kJ mol–1) and C–C bond (bond enthalpy 348 kJ mol–1). The C≡C bond length is shorter (120 pm) than those of C=C (133 pm) and C–C (154 pm). Electron cloud between two carbon atoms is cylindrically symmetrical about the internuclear axis. Thus, ethyne is a linear molecule.
# A-level Chemistry/OCR (Salters)/Amino acids
## α-Amino acids

* The general structure of an α-amino acid. The α-carbon is displayed in orange, and the side chain is denoted by R. This style of diagram does not indicate whether the amino acid is an L or a D enantiomer.
* The stereochemistry of an L-amino acid. All amino acids in nature are L-amino acids, except for bacterial cell walls and the odd w:en:cone snail or two.
* A skeletal formula of a general α-amino acid. The α-carbon is displayed as an orange circle
* The skeletal formula of a general L-α-amino acid, the enantiomeric form found in nature.
* The skeletal formula of a general D-α-amino acid, the enantiomeric form not found in nature. D-amino acids can be synthesised artificially in a laboratory.

## The twenty protein-forming amino acids

* glycine Gly, G
* L-alanine Ala, A
* L-valine Val, V
* L-leucine Leu, L
* L-isoleucine Ile, I
* L-phenylalanine Phe, F
* L-proline Pro, P
* L-tryptophan Trp, W
* L-serine Ser, S
* L-threonine Thr, T
* L-cysteine Cys, C
* L-methionine Met, M
* L-aspartic acid Asp, D
* L-glutamic acid Glu, E
* L-asparagine Asn, N
* L-glutamine Gln, Q
* L-tyrosine Tyr, Y
* L-histidine His, H
* L-lysine Lys, K
* L-arginine Arg, R

## Reactions of amino acids

Amino acids can undergo condensation reactions, forming polypeptides.
# A-level Chemistry/OCR/Equilibria, Energetics and Elements/Energy/Lattice Enthalpy

Lattice enthalpy is the enthalpy change when one molecule of an ionic crystal is formed from its constituent ions in their gaseous state at standard conditions (101kPa pressure and 298K temperature).
# A-level Chemistry/OCR/Group 7

Group 7 consists of highly reactive non-metals called halogens.
Some main properties of the first 4 elements in group 7 are listed below.
| halogen | formula | colour | physical state | electronic structure |
| fluorine | F$_2$ | pale yellow | gas | 1s$^2$2s$^2$2p$^5$ |
| chlorine | Cl$_2$ | greenish-yellow | gas | 1s$^2$2s$^2$2p$^6$3s$^2$3p$^5$ |
| bromine | Br$_2$ | red-brown | liquid | 1s$^2$2s$^2$2p$^6$3s$^2$3p$^6$4s$^2$3d$^{10}$4p$^5$ |
| iodine | I$_2$ | grey black, purple if in vapour form | solid | 1s$^2$2s$^2$2p$^6$3s$^2$3p$^6$4s$^2$3d$^{10}$4p$^6$5s$^2$4d$^{10}$5p$^5$ |

## Trends

The boiling and melting points increase as you go down the group. This is because the strength of the Van Der Waals forces (or induced dipole-dipole interactions) increases since the atoms have more electrons as you descend the group. This trend is highlighted by the fact that the physical state of the halogens changes from gaseous (fluorine) to solid (iodine) down the group. Volatility decreases down the group as the boiling points increase.
As you go down group 7, the halogens become less reactive.
This is because:
Decreasing reactivity,
- Atomic radius increases.
- Nuclear charge increases, so the nuclear attraction on the outer electrons are stronger.
- Electron Shielding increases and outweighs the nuclear attraction.

## Redox

-Halogens are oxidising agents
-Halogen + electron -> Halide Ion or Reduction agent
# A Roller Coaster Ride through Relativity/Appendix D
## The Addition of Speeds

Consider a spaceship A of length l$_A$ travelling past you at a speed v$_A$ passing a second spaceship B of length l$_B$ travelling in the opposite direction at a speed v$_B$ (both speeds measured with reference to you). The question we need to answer is what speed v$_X$ does B appear to be going past the astronauts in A?
We need to consider two vital events; first contact, when the nose cones of the two spaceships meet and second contact when the two tails part.
What is more, let us suppose that these two events occur at the same place from your point of view. This means that the spaceships have to be just the right length so that they both pass you in the same time. Note that from your point of view, both ships are contracted by the factors γ$_A$ and γ$_B$ respectively.
Now what does the commander of ship A see? He sees you travelling past at a speed v$_A$ and also ship B travelling past at some greater speed v$_X$.
Note that to the occupants of ship A, B is length contracted by a factor γ$_X$.
Now commander A can calculate the time between first and second contact in two ways. First he sees you travelling a distance l$_A$ at a speed v$_A$. Secondly, he sees ship B (whose length is contracted to l$_B$/γ$_X$) travel a distance equal to l$_A$ + l$_B$/γ$_X$ at a speed v$_X$. It follows that:
* ${l_{A} \over v_{A}}={l_{A}+l_{B}/\gamma _{X} \over v_{X}}$
* $l_{A}v_{X}=l_{A}v_{A}+l_{B}v_{Z}/\gamma _{X}$
* $l_{A}(v_{X}-v_{A})=l_{A}v_{B}/\gamma _{X}$
An identical argument from commander B's point of view leads to:
* $l_{B}(v_{X}-v_{B})=l_{B}v_{A}/\gamma _{X}$
(It should be pointed out that because of the invariance of velocity, if commander A sees ship B moving at a speed v$_X$ then commander B will see ship A moving at exactly the same speed and contracted by the same γ factor.)
Now multiplying the two equations together eliminates the lengths of the two ships and leaves us with a relation between the three velocities. The rest is just algebra.
* $(v_{X}-v_{A})(v_{X}-v_{B})=v_{A}v_{B}/\gamma _{X}^{2}$
Now
* $\gamma _{X}={1 \over {\sqrt {1-v^{2}/c^{2}}}}$
so:
* $1/\gamma _{X}^{2}=1-v_{X}^{2}/c^{2}=(c^{2}-v_{X}^{2})/c^{2}$
hence:
* $(v_{X}-v_{A})(v_{X}-v_{B})=v_{A}v_{B}(c^{2}-v_{X}^{2})/c^{2}$
from which we obtain by straightforward algebra the result we desire:
* $v_{x}={v_{A}+v_{B} \over 1+v_{A}v_{B}/c^{2}}$
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# A Roller Coaster Ride through Relativity/Appendix H
## The Gravitational Potential at the surface of a star

The force of gravity on a mass m at a distance r away from a star of mass M is equal to:
* $F={GMm \over r^{2}}$
The work done in pulling the mass from the surface of the star out to infinity is therefore:
* $W=\int _{r}^{\infty }{GMm \over r^{2}}dr$
This works out to be
* $W={GMm \over r}$
and therefore the gravitational potential difference Δφ between the surface and ∞ is
* $\Delta \phi ={w \over m}={GM \over R}$
Now by definition, the gravitational potential at ∞ is zero so the potential at the surface is negative, hence:
* $\phi _{s}=-{GM \over R}$
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# A Roller Coaster Ride through Relativity/Appendix G
## The relation between Energy and Momentum

The total relativistic energy E and the relativistic momentum p of a body are given by the following expressions:
* $E=\gamma M_{0}c^{2}={M_{0}c^{2} \over {\sqrt {1-v^{2}/c^{2}}}}$
* $p=\gamma M_{0}v={M_{0}v \over {\sqrt {1-v^{2}/c^{2}}}}$
We wish to eliminate v from these equations. First square and multiply across:
* $E^{2}(1-v^{2}/c^{2})=M_{0}^{2}c^{4}$
* $p^{2}(1-v^{2}/c^{2})=M_{0}^{2}v^{2}$
Now for a diabolically cunning move, multiply the second equation by c$^2$ and subtract!
* $(E^{2}-p^{2}c^{2})(1-v^{2}/c^{2})=m_{0}^{2}c^{4}(1-v^{2}/c^{2})$
from which we obtain:
* $E^{2}-p^{2}c^{2}=M_{0}^{2}c^{4}$
An alternative (and in my opinion better) way of writing this equation is:
* $E^{2}-E_{0}^{2}=p^{2}c^{2}$
where E$_0$ is the rest-mass energy of the body.
It is instructive to compare this expression with the non-relativistic relation between energy and momentum which is calculated as follows
* $KE={\tfrac {1}{2}}Mv^{2}~~~{\text{and}}~~~p=Mv$
so
* $KE={p^{2} \over 2M}$
It is not easy to see, at first, how the relativistic expression will reduce (as it must) to the non-relativistic one when v is small, but it does. Watch!
Since
* $E^{2}-E_{0}^{2}=p^{2}c^{2}$
we can write
* $(E-E_{0})(E+E_{0})=p^{2}c^{2}$
Now (E - E0) is just the relativistic kinetic energy KE$_r$ which, at low speeds approximates to the ordinary kinetic energy KE.
At low speeds, the total relativistic energy E and the rest-mass energy E$_0$ are virtually equal and equal to Mc$^2$ so:
* $KE~.~2Mc^{2}=p^{2}c^{2}$
from which it is easy to see that
* $KE={p^{2} \over 2M}$
as expected.
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# A Roller Coaster Ride through Relativity/Appendix E
## Travelling 'faster than light'

If you travel for a distance x at a speed v, owing to length contraction, the proper time interval (ie the number of years you age during the journey) between setting out and arriving will be:
* $T={x \over \gamma v}=x{\sqrt {1-v^{2}/c^{2} \over v}}={x{\sqrt {1-v^{2}/c^{2}}} \over cv}$
* $T={x \over c}{\sqrt {c^{2}/v^{2}-1}}$
A light beam, on the other hand, will actually take:
* $T={x \over c}$
If we put these two expression equal, we can find out at what speed it is necessary to travel in order to get the effect of travelling as fast as light.
* ${x \over c}{\sqrt {c^{2}/v^{2}-1}}={x \over c}$
* ${\sqrt {c^{2}/v^{2}-1}}=1$
* $c^{2}/v^{2}-1=1$
* $c^{2}=2v^{2}$
* $v={c \over {\sqrt {2}}}$
ie 71% of the speed of light.
Let me just say again what this means. You are not actually travelling faster than light – but you will reach Alpha Centauri, 4 light years away, in only 4 of your years.
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# A Guide To PIC Microcontroller Documentation/Cover

A Guide to PIC Microcontroller Documentation
# A Guide To PIC Microcontroller Documentation/Introduction to PIC microcontroller and DSC products
## Methodology behind PIC® controller documentation

Microcontrollers and digital signal processors (DSPs) are challenging products to document. On the one hand, the semiconductor vendor has to describe the functionality of the device's processing core, the functionality and possible settings of peripherals and the electrical and packaging specifications of the device. This description needs to concentrate on the raw functionality of the device's circuitry and the registers which they form. For example, a UART (Universal Asynchronous Receiver Transmitter) peripheral's functionality, as described in a datasheet, focuses upon, among other things, setting up the related transmit and receive pins of the device for use as a serial interface, how to calculate the required baudrate settings and how to enable parity support.
On the other hand, raw details on functionality and setup alone cannot inform a developer how to use that peripheral, processor or other feature in an actual application. Using our UART example again we know that a UART can be used in a variety of serial interfacing standards such as RS-232 and RS-485 amongst others. In addition that standard may have standardized software layer with which it is commonly used (for example ANSI escape sequences used with VT100), and a common circuit layout external to the controller to implement the required signalling (for example a MAX-232 family transceiver used with RS-232).
A further challenge documenting controller products is due to their infinite flexibility, as programmable products, and the fact that the software can be written in a variety of different programming languages using a broad range of software tools from different vendors of which some, or perhaps none, come from the silicon vendor themselves.
Lastly there is the issue of the software programs and hardware tools used for creating and debugging the firmware for the controller and the programming tools used for small production runs or mass-production.
As a result, datasheets alone typically contain around 100 pages, often running to several hundred pages, and in the interest of keeping the size of the datasheet manageable, much common and implementation or application specific data is located in various other documents with names such as "Family Reference Manual", "Application Note" or "Programming Specification".
# A Guide To PIC Microcontroller Documentation/Glossary
## D

* DSP - Digital Signal Processor - processor designed to efficiently process discrete signal data (e.g. audio, video). Key processor instruction on a DSP is the MAC instruction (multiply and accumulate) which allows a single piece of data to be multiplied by a single coefficient value and added to the value currently in the processors accumulator, all in a single processing cycle.
* DSC - Digital Signal Controller - acronym used by Microchip Technology to define their dsPIC family of products which contain a microprocessing core and a DSP. The alternative definition is used to highlight the products embedded control properties (fixed latency times for jumps into interrupt routines, fixed instruction processing time) regardless of which instruction the processor is currently processing, which is typically not the case for pure DSP architectures.

## W

* Workaround - typically a software solution to a hardware problem in a controller product. Usually involves reordering code to avoid a hardware problem, or changing a setting under certain situations.