# (Outdated) Notes {% tabs %} {% tab title="S1" %} ## Models of the particulate nature of matter * Particle nature * **Matter** * Pure substance * Has definite and constant composition * **Elements** * All atoms have the same number of protons * *Ex. Aluminum* * **Compound** * A fixed ratio of differing atoms * *Ex. Water* * **Mixture** * A combination of pure substances that retain their individual properties * **Homogenous** * Uniform composition (seems like it's made up of one thing) * *Ex. Honey* * **Heterogenous** * Non-uniform composition (can see what it's made up of) * *Ex. Trail mix (of different nuts)* * States of matter * Solids (melting >) Liquid (vaporizing >) Gas * Solid (< precipitating, sublimating >) Gas
* Methods of Separating Mixtures' Particles * **Solvation** * Based on solubility of different solvents * *Sand, salty water* * **Filtration** * Based on size of particles using a membrane * *Salt, water* * **Crystallization** * Based on ease of evaporation * *Salt, water* * **Chromatography** * Based on particle's affinity varieties for the mobile phase (solvent) or stationary phase (paper) * **Distillation** * Based on different boiling points * *Ex. alcohol, water* * Atom * Components * Proton * Positive * \~1 amu * Neutron * Neutral * \~1 amu * Electron * Negative * \~0 amu * Atomic notation
* A, mass number * \# protons - # neutrons * B, atomic number * \# protons (identifies element X) * ?, charge caused by loss or gain of electrons * X, chemical symbol * \# of protons defines this * **Isotopes** * Same element (same # of protons) but different # of neutrons * Some isotopes are more stable than others, more available in nature * Differences between isotopes * Same chemical properties due to same # of valence electrons * Slightly different physical properties due to # of neutrons * Relative atomic mass $$A\_R=x×A\_1×A\_2×A\_3...$$ * **Mass spectrometry** * **Simply ionized** * Loses an electron, detected and presented on a mass spectra * X-axis is m/z, which is mass/charge, Y-axis % of abundance * **Doubly ionized** * Loses two electrons, also detected on mass spectra * Divides mass on X-axis by 2, Y-axis is % of abundance * Determining relative atomic mass from a mass spectra * Consider 100 atoms $$M\_{100}=(A\_1×m/z)(A\_2×m/z)...$$ M, relative atomic mass; A, abundance %, m/z, X-axis data from spectra * **Electromagnetic spectrum** * Light splits through a prism into red to violet * Each color has it's own wavelength, with red = large, violet = small wavelengths * Difference in energy, red = low, violet = high * Available in IB data booklet (nanometers = nm = $$×10^{-9}$$) $$C = f/λ$$ * White light passes through a gas, then exits having absorbed some colors and some not * *Ex. A high energy gas glows and reflects a specific color. Not continuous, known as emission or line spectrum* * *Ex. A low energy gas gives an absorption spectrum* * If the band that is missing in the absorption spectrum is the same band missing in the emission spectrum means it's the same gas * **Bohr's model** * Electrons exist at discreet energy levels * These energy levels get closer together (converge) at higher energies * Discrete colors are produced when electrons transition to lower energy levels (discrete colors are absorbed when electrons transition to a higher level) * *Ex. High energy colors are produced from electrons moving from higher levels to a higher level.* * The spectra has exclusions of energies produced too high and too low to notice. So when they move from closer to more distant ones, they produce the absorption spectrum * Electron configuration * Energy level diagram * **Aufbau principle**, electrons fill the lowest energy levels first * **Pauli exclusion principl**e, an orbital can hold a maximum of 2 electrons with opposite spins
* **Hund's rule**, one electron in each sublevel with parallel spin before doubling up * Orbital configurations * 2s orbitals, spherical + max. 2 electrons * 3×2p orbitals, px/py/pz + dumbbell/peanut + max. 6 electrons * d orbitals, complex + max. 10 electrons * f orbitals, most complex + max. 14 electrons * Energy levels (n) to possible orbitals = $$n^2$$ * How to find the electron configuration from atomic notation or an element * A block can represent a orbital
* For example, helium (He) with 2 protons, so 2 electrons
* For example, carbon (C) with 6 proton, so 6 electrons * $$1s^22s^22p^2$$ * For explanation purposes only, the expanded form would be $$1s^22s^22px^12py^1$$ as due to Hund's rule, the electrons go to empty sublevels first before pairing up
* For example, potassium (K) with 19 protons, so 19 electrons * $$1s^22s^22p^63s^23p^64s^1$$ * Shorthand electron configuration * Go to nearest noble gas and replace the majority of electrons, adding the extra electron change from the original element * For K it's Argon (Ar), 18 electrons * $$\[Ar]4s^1$$ * **Numbered steps** **1)** Find number of protons of the element (bottom left in atomic notation, Z)\ **2)** Find charge of the element (top right in atomic notation, ?)\ **3)** Subtract charge from # of protons\ \&#xNAN;*(ex. C has 6 protons, if 2- charge, 8 electrons since 6-(-2)=8)*\ **4)** Fill up orbitals by applying Aufbau's principle, where the lowest ones are filled first\ **5)** Apply Pauli's exclusion principle, where each orbital can only have 2 electrons\ **6)** Apply Hund's rule, where in each sublevel (like all of p orbitals) an electron goes to an empty box rather than doubling up first\ \&#xNAN;*(as seen in C's electron configuration)*\ **7)** When going to the next energy level, electrons go back to the s orbital, then fill p, d, etc.\ **8)** Write the electrons in every sublevel as a superscript to the orbital letter
* Order of filling up orbitals is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, and so on
* Follow a stitching pattern when filling up orbitals
* Exceptions * Chromium (Cr) with 24 protons, so 24 electrons * Expectation is $$\[Ar]4s^23d^4$$ * Reality is $$\[Ar]4s^13d^5$$ * Copper (Cu) with 29 protons, so 29 electrons * Expectation is $$\[Ar]4s^23d^9$$ * Reality is $$\[Ar]4s^13d^{10}$$ * This is because half full and full orbitals are more stable than partially full orbitals * Ions * Anions (-) * Add the charge to the outermost valence shell * $${}\_{8}O^{2-}=1s^22s^22p^{(4+2)}=(...)2p^6$$ * Cations (+) * Focus on the highest principle quantum number * $${}\_{26}F^{2+}=\[Ar]4s^{(2-2)}3d^6=\[Ar]3d^6$$ * **Emission spectra** * Focuses on the application of two equations given in the data booklet * $$E=hf$$ * $$c=fλ$$
* Why does that band show up? * It's when an electron from the 3rd energy level drops down to the 2nd energy level, producing a red color emission spectra (cause 656 nm is within red's wavelength) * All finish at a transition finishing at the 2nd energy level * **What's the energy change of an electron associated with the red spectra in hydrogen?** * Given $$λ=656×10^{-9}$$ m, $$n=6.63×10^{-34}$$ Js * Rearrange given equation to $$\frac{c}{λ}=f$$ * Substitute $$f$$ in $$E=hf$$ to get $$E=\frac{hc}{λ}$$ * Substitute all values and solve $$E=\frac{6.63×10^{-34}Js×3.00×10^8ms^{-1}}{6.56×10^{-9}m}=3.03×10^{-19}J$$ * Ionization * $$X\_{(g)}+IE⇀X\_{(g)}^{-1}+e^-$$ * With the addition of ionization energy, the element forms a cation as an electron is released * $$IE=$$ **Ionization energy** * From data booklet, $$IE=738 kJmol^{-1}$$ * **What wavelength of the electromagnetic spectrum is absorbed to cause the first ionization of the magnesium atom?** * As seen previously, derive $$E=\frac{hc}{λ}$$, isolate λ * Magnesium (Mg)'s electron configuration is $$1s^22s^22p^63s^{(2-1)}$$ * -1 from ionization * The IE from the data booklet is per mole, but the wavelength is per electron * Divide IE with Avogadro's number * $$\frac{738kJmol^{-1}}{6.02×10}=1.226×10^{-18}J$$ per electron from a photon * Substitute values into $$λ=\frac{hc}{E}$$ * $$\frac{6.63×10^{-34}Js×3.00×10^8ms^{-1}}{1.226×10^{-18}J}=1.62×10^{-7}m$$ or 162 nm * The units cancel out to leave $$m$$ cause it's a wavelength * **Successive ionization** * One element and continually remove electrons * For example, sodium (Na)'s electron configuration is $$1s^22s^22p^63s^1$$ * $$Na\_{(g)}+IE⇀Na^+\_{(g)}+e^-$$ * $$f(x) = x \* e^{2 pi i \xi x}$$ {% endtab %} {% endtabs %} [Sirius Revision's playlists](https://www.youtube.com/@siriusrevision/playlists) {% hint style="info" %} To the sadness of all 2 people who read this, I will not be finishing these notes. {% endhint %} Read my complete chemistry notes on [ZNotes](https://znotes.org/). --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://shagun.gitbook.io/mystuff/hl/chemistry/rush-review.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.