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Physics, Chemistry, PHYSICS THIS WAY >>>>>, CHEMISTRY THIS…
Physics
Nuclear
Atoms, isotopes and radioisotopes
Atom
Atomic Structure
Nucleus contains protons and neutrons, same elements have the same amount of protons
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Nucleus is relatively small compared to the size of the atom; 1/10,000 - 1/100,000
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Isotopes
Specific elements contain the same number of protons; isotopes are elements with the same number of protons, but varying numbers of neutrons
Radioisotopes
Most atoms exist as stable isotopes, however there are some that naturally occur unstable.
Spontaneous transmutation is when an unstable nucleus emits a particle to become more stable. It then is considered a different element or isotope
Artificial Transmutation
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Synthetic or forced radioisotopes can be made through neutron absorption, this is when we bombard a stable isotope with neutrons. These neutrons then get absorbed into the nucleus and create a radioisotope
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Stability of the nucleus
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The strong nuclear force is the force that exists between the nucleons and holds the nucleus together
Other forces like electromagnetic force still exist but are weaker in comparison so cannot overcome the strong nuclear force at these extremely small instances
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Decay
Nuclear decay comes in three forms, alpha, beta and gamma
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Alpha decay happens when the strong nuclear force cannot hold the large nucleus together. This results in a alpha particle being emitted
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Gamma decay is high-energy photons. They are emitted when a nucleus decays from an excited state to a lower state, after alpha or beta decay the daughter nucleus often has excess energy, slight rearrangement of the nucleons leads to energy being emitted as gamma usually.
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Half-Life
Half-life is the time taken for a sample of a radioactive isotope to decay to half its original amount OR the time taken for the activity to decrease to half
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Chemistry
Periodic Trends
Atomic Radius
A measurement used for the size of atoms. At a simple level it can be regarded as the distance from the nucleus to the outermost electron/s
Increases when going down due to more electron shells due to more electrons in the atom and decreases when going left to right due to a higher electro static attraction to the nucleus and its electrons because of the higher amount of protons
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Valency
The number of chemical bonds a element can form this can be calculated but determining the number of electrons a metal lose or a atom of a non-metal will gain
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First Ionization energy
The energy required to remove the most loosely bound electron from the atom in the neutral gaseous state
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Three things affect this:
- Atoms nuclear charge - more positive nucleus means the electrons are more strongly attracted
- Distance between the nucleus and the outermost electrons - Attraction reduces over distance
- Shielding inner electrons - electrons in-between the nucleus and the outermost electrons shield the attraction and add repulsive forces between the two negatives
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Materials and Separation
Separation
Distillation is essentially evaporation but captures the vapor rather than the un vaporized substance
Gravity Separation is separation through density, add a mixture to water and the less dense particles will float and the more dense will sink. (also works with centrifugal separation via density)
Evaporation is often pair with filtration by separating through a difference in boiling points, a solution will be heated and the lower boiling point substance will be evaporated while the other remains
Filtration can be used to separate particles based on their solubility, add water or a dissolvent to a mixture and if there is a difference in solubility the dissolved water will pass through the filter and the non-dissolved will be separated
Sieving is separation based on particle size, done by using a mesh with varied gape size to allow larger/smaller particles through
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Nanomaterials
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CD, DVD, Blu-ray, Carbon nanotubes, etc
Nanomaterials have extremely high surface areas which makes them extremely good at reacting, this means that they have a lot of uses
They are able to be homogenous without being dissolved meaning normally insoluble materials now can act soluble
They absorb extremely well meaning they can transport things through air, skin and even cells
Bonding and Properties
Metallic
Metallic bonding is comprised of a positively charged lattice of ions in a regular arrangement, but surrounded by a sea of delocalized electrons
Simply put, it is the electrostatic force of attraction between positive ions and delocalized electrons
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Ionic
The complete transfer of valence electrons between atoms. It generates two oppositely charged ions which are electrostatically charged and forms a fixed lattice of alternating ionic charges :
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Covalent
Between two non-metal elements that share electrons between them to complete their ouster shell and become stable
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Organic Chemistry
Alkane, Alkene, Alkyne
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Alkene is a unsaturated hydrocarbon which contains a double bond and can consists of other elements as well
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Naming
- Find the longest chain of carbons
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- Look for branches and the amount of carbons attached
Atomic interaction
Spectroscopy
Electron Energy
There is also absorption spectroscopy which rather than measuring the emitted light, you measure the light that passes through the atom and does not get absorbed, leaving parts of the spectrum shown blank as that light has been absorbed
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An electron can jump to a higher energy level if it absorbs the energy exactly the same as the the difference in energy between the lower level and the higher level
When an electron has jumped to a higher level it is considered excited and unstable so eventually returns to the lower energy level a.k.a ground state, this releases energy in the form of photons and is visible to us in the light spectrum
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Electrons can be excited through energy transfer to them and this can be done in many was one being heat
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Electrons in energy levels close to the nucleus have the lowest energies and experience the strongest interaction with the nucleus
Each element has a varied amount of protons within the nucleus, this means the attraction to the electrons will also vary as the electrostatic forces change
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Spectroscopy is the study of the way that radiation interacts with matter,
Spectrometer is an instrument to measure the wavelength of light,
Spectrum is a plot of the colour profile and present wave lengths
Properties of Atoms
Atomic Structure
Nucleus is composed of protons and neutrons, and surrounded by the orbitals called electrons
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Relative Atomic Mass
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The standard of measuring the masses of individual is the most common isotope of carbon, carbon-12, and is given the value of 12 units, therefore one unit is one twelfth of a carbon-12 atom
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Isotopes
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Isotopes are Atoms with the same number of protons but a varying amount of neutrons within the nucleus, some are stable some are not and unstable isotopes are called radio-isotopes
Mass
Molar Masses
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Due to the incredibly large number of atoms in anything we measure a unit for measuring atoms is made - the mole
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Charge
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Charge contains three attributes, positive, negative and neutral.
Protons = Positive
Neutrons = Neutral
Electrons = Negative
electron configuration
Electrons are found at specific energy levels or orbitals, each orbital can only hold a specific number of electrons before moving to a higher orbital
The number electrons per shell is configured through the formula 2*(shell number)^2, however there are some intricacies to it
For the first twenty electrons the configuration is as follows 2, 8, 8, 2 this is all that is needed to be known
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Chemical Reactions
Solubility
Solubility is the ability for a substance to dissolve in water,
Can vary from slightly soluble to bull solubility
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