IMPORTANT LAWS
Source: Pearson higher level chemistry for the IB diploma (2nd edition) by Catrin Brown and Mike Ford
These laws are very important and in the IB chemistry syllabus.
AUFBAU'S PRINCIPLE
Aufbau's Principle states that electrons are placed into orbitals of lowest energy first.
HEISENBERG'S UNCERTAINTY PRINCIPLE
According to Heisenberg's uncertainty principle we cannot know where an electron is at any given moment in time, as any attempt to measure an electron's position will disturb its motion. The act of focusing radiation to locate the electron gives the electron a random ''kick'' which sends it hurtling off in a random direction.
THE PAULI EXCLUSION PRINCIPLE
The Pauli Exclusion Principle states that no more than two electrons can occupy any one orbital, and if two electrons are in the same orbital they must spin in opposite directions.
HUND'S RULE
Hund's rule states that if more than one orbital in a sub-level is available, electrons will occupy different orbitals with parallel spins.
RESEARCH
Research at The Atom Project- By Arshyia Mehran involves constant analysis of the hypotheses we explore. Since 2000, we have been driven by this mission of discovery. Read on to find out more about our latest work.
IB CHEMISTRY DATA BOOKLET
The electromagnetic spectrum
As we can see, radio waves have the lowest energy because they have the longest wavelengths and lowest frequency while x-rays and gamma rays have far shorter wavelengths and much higher frequencies meaning that they have higher energies.
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RESEARCH
Research at The Atom Project- By Arshyia Mehran involves constant analysis of the hypotheses we explore. Since 2000, we have been driven by this mission of discovery. Read on to find out more about our latest work.
THE VISIBLE LIGHT SPECTRUM
Visible light is the only part of the electromagnetic spectrum which we can actually see, red light is the slowest as it has the longest wavelength and thus the lowest energy while violet has the highest energy as it has the shortest wavelength, therefore a fun fact is that you actually see violet before red light. Also as the different colors travel at different speeds they diffract at different angles allowing rainbows to form. Also all the waves in the electromagnetic spectrum are transverse waves which all oscillate perpendicularly to the direction of the wave and in a vacuum, all transverse waves move at the speed of light which is (3 x 10^8) meters per second.
KEY PUBLICATIONS
We are proud to showcase the results of research undertaken by members of our interdisciplinary Scientific Research Institute. Our work and findings have been published in a number of prestigious publications in our field.
This is a labelled diagram of all the parts of a transverse wave.
KEY KNOWLEDGE AND RECAP
Atoms contain a positively charged and dense nucleus composed of protons and neutrons.
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Negatively charged electrons occupy the space outside the nucleus.
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The mass spectrometer is used to determine the relative atomic mass of an element from its isotopic composition.
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In the nuclear symbol aXz, a is the atomic number, X is the symbol for the element and z is the relative atomic mass of the element taken as a percentage of the atomic masses of their isotopes and their percentage abundance on the planet.
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the percentage abundance of bismuth is (100 x 208.98)/100= 208.98 which is the relative atomic mass of bismuth because bismuth only has one natural isotope.
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Emission spectra are produced when photons are emitted from atoms as excited electrons return to a lower energy level like their ground state for example.
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The main energy level or shell is given an integer number n and can hold a maximum number of electrons, 2n^2 causing electronic configuration to start with 2,8,18,32.
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A more detailed model of the atom describes the division of the main energy level into s, p, d, and f sub-levels of successively higher energies where s has the lowest energy and f has the highest energy, also the s sub shell holds 2 electrons, the p sub shell holds 6 electrons, the d sub shell holds 10 electrons, and the f sub shell holds 14 electrons, resulting in 2,8,18,32 being broken down into 2,2+6,2+6+10,2+6+10+14.
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Sub levels contain a fixed number of orbitals, regions of space where there is a high probability of finding an electron.
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Each orbital has a defined energy state for a given electronic configuration and chemical environment and can hold two electrons of opposite spin as stated in Hund's rule.
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In an emission spectrum, the limit of convergence at higher frequency corresponds to the first ionization energy.
HYDROGEN SPECTRUM
SOURCE: KOGNITY
The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels, which converge at higher energies.
RESEARCH
Primary Areas of Interest
CONTINUOUS SPECTRA
When the absorption and the emission spectra of a species are put together, they form a continuous spectrum. An absorption spectrum is a plot drawn between the absorbance of a photon of light released from an excited electron returning to lower energy levels and the wavelength. Sometimes instead of the wavelength, we can also use the frequency or wave number in the x-axis. The absorption spectrum is characteristic for a given molecule or an atom. Therefore, we can use it in identifying or confirming the identity of a particular species.
LINE SPECTRUM
There are two types of line spectrum; an absorption and an emission spectrum, in an absorption spectrum the lines represent the wavelengths of light that were absorbed by matter and in an emission spectrum the lines represent the wavelengths of light that were reflected, this an absorption spectrum is the inverse of an emission spectrum, while an absorption and emission spectrum combined make up a continuous spectra.
HYDROGEN EMISSION SPECTRUM
source: Kognity
The hydrogen emission spectrum is the simplest emission spectrum of the elements because we are looking at the transitions of just one electron per atom. As a voltage is passed through a sample of hydrogen, electrons are excited to higher energy levels. The extent to which any particular electron is promoted depends on how much energy the electron absorbs.
A longer arrow means that more energy was emitted in an emission spectrum.
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Electron transitions to the n = 1 energy level emit energy that corresponds to the wavelength or frequency of ultraviolet (UV) radiation.
Electron transitions to the n = 2 energy level emit energy that corresponds to the wavelength or frequency of visible light.
Electron transitions to the n = 3 energy level emit energy that corresponds to the wavelength or frequency of infrared (IR) radiation.
ATOMIC ORBITALS AND THEIR STRUCTURE
Source: Kognity
S ORBITAL
The s orbital is spherical in shape and contains one set of two electrons which spin in opposite directions.
P ORBITAL
The p orbital has a dumbell shape on each axis (x,y and z) and each dumbell holds a pair of two electrons which spin in opposite directions thus the p orbital as a whole can hold up to six electrons.