What is the purpose of atomic absorption spectroscopy (AAS)?
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To measure how electromagnetic radiation is absorbed by an atomised sample.
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What is the purpose of atomic absorption spectroscopy (AAS)?
To measure how electromagnetic radiation is absorbed by an atomised sample.
What does each line in an emission spectrum represent?
A transition between definite energy levels.
What happens to electrons in AAS when radiation is absorbed?
Electrons are promoted to higher energy levels.
Which electrons are lost first when transition elements form ions?
The 4s electrons.
What does the Pauli Exclusion Principle state?
An orbital cannot contain more than two electrons, and they must have opposite spins.
What is produced by measuring the intensity of absorbed light in AAS?
An absorption spectrum.
What is the electromagnetic spectrum?
The arrangement of different types of radiation in order of wavelength.
What are the particles called that electromagnetic radiation behaves like when absorbed or emitted?
Photons.
What is the order of priority for electron pairs when predicting molecular shape?
Non-bonding pair/non-bonding pair > non-bonding pair/bonding pair > bonding pair/bonding pair.
What does frequency (f) measure in electromagnetic waves?
The number of waves that travel past a point in one second, measured in hertz (Hz).
How does Atomic Emission Spectroscopy (AES) work?
It measures radiation emitted when excited electrons fall to lower energy states.
What is electromagnetic radiation?
A form of energy that includes light, X-rays, radio signals, and microwaves.
What determines the shape of a molecule or ion?
The shapes adopted by the atoms based on the arrangement of electron pairs.
What does desorption mean in the context of catalysis?
The product molecules break away from the active site.
What can be used to show the arrangement of electron pairs in a molecule?
Electron dot diagrams.
What is produced when light energy is emitted by an atom?
A spectrum made up of a series of lines at discrete energy levels.
Why is chromium considered d5 instead of d4?
Due to the increased stability of having half-filled d orbitals.
What properties do electrons display in atomic spectra?
Electrons display properties of both particles and waves.
What are transition metals characterized by?
An incomplete d subshell in at least one of their ions.
What does a photon carry that is proportional to the frequency of radiation?
Quantised energy.
How do high frequency photons compare to low frequency photons in terms of energy transfer?
High frequency photons can transfer greater amounts of energy than low frequency photons.
What effect do water ligands have on d orbitals?
They split the d orbitals.
What is Hund's rule?
When degenerate orbitals are available, electrons will fill each singly with parallel spins before pairing.
What allows transition metals to exhibit variable valency?
The ability to lose 4s and some or all 3d electrons.
What does VSEPR stand for?
Valence Shell Electron Pair Repulsion.
What happens when visible light shines on a transition metal compound?
The green component is absorbed, causing an electron to move from a low energy d orbital to a high energy d orbital.
What type of transition occurs when an electron moves between d orbitals?
A d to d transition.
What factors influence the splitting of d orbitals?
The extent of splitting depends largely on the nature of the ligands and their arrangement.
What causes the lines seen in the ultraviolet region of an emission spectrum?
Excited electrons falling back to the ground state (n=1).
How can electromagnetic radiation be described?
As both a wave and a particle, exhibiting dual nature.
What principle governs the filling of d orbitals?
The aufbau principle.
What does the spin quantum number (ms) indicate?
The direction of spin and can have values of +½ or -½.
What is the ligand name for chloride?
Chlorido.
What is the ligand name for hydroxide?
Hydroxido.
What type of ligands are more likely to absorb visible light and make complexes colored?
Weak field ligands such as H2O.
Which elements are exceptions in the transition elements?
Chromium and copper.
What is the basic principle of VSEPR theory?
The shape adopted by a molecule or ion minimizes repulsive forces.
How do electrons behave in an atom?
As standing (stationary) waves.
What happens to bond angles when both bonding and non-bonding pairs are present?
The angles can be modified due to repulsion differences.
How can oxidation be redefined?
As an increase in oxidation number.
What do compounds with metals in low oxidation states typically act as?
Reducing agents.
What technique is used to study the effects of d-d transitions?
Spectroscopy.
How does the concentration of a solution affect its color and light absorption?
A more concentrated solution absorbs more light and is darker in color.
What does it mean for d orbitals to be degenerate?
It means that they are of equal energy.
What is the result of d-d transitions in terms of energy?
Electrons in lower energy d-orbitals absorb energy and move to higher energy d-orbitals.
What is the relationship between energy difference and frequency of the lines in the spectrum?
A larger difference in energy causes lines of higher frequency.
What shape do s orbitals have?
Spherical.
What is a coordination compound?
A complex consisting of a central metal ion surrounded by ligands.
How are ligands classified based on the number of electron pairs they donate?
As monodentate, bidentate, up to hexadentate.
What do Atomic Emission Spectroscopy (AES) and Atomic Absorption Spectroscopy (AAS) measure?
AES measures emitted radiation; AAS measures absorbed radiation.
How can the intensity of absorbed light be used in AAS?
To determine the amount of each element in the sample.
What does the Aufbau principle state?
Electrons fill orbitals in order of increasing energy.
What does the Pauli exclusion principle state?
No two electrons in one atom can have the same set of four quantum numbers; thus, no orbital can hold more than two electrons with opposite spins.
Why does the 4s subshell fill before the 3d subshell?
The 4s subshell is larger and further from the nucleus, but the 3d subshell has more energy.
What does the angular momentum number (l) determine?
The shape of the subshell and can have values from 0 to n - 1.
What type of bond is formed between ligands and the central metal atom?
Dative covalent bonds.
What type of ligands are more likely to cause d-d transitions in the UV region?
Strong field ligands such as CN-.
What are the two types of catalysts?
Homogeneous and heterogeneous catalysts.
Why are chromium and copper exceptions in electron configuration?
Due to the special stability associated with the d subshell being half filled or completely filled.
What is the arrangement of electron pairs based on?
They arrange to maximize separation and minimize repulsion.
How does the presence of non-bonding electron pairs affect molecular shape?
Non-bonding pairs repel more than bonding pairs, modifying angles between them.
What does it mean for electrons to be quantised?
They can possess fixed amounts of energy known as quanta.
What does the magnetic quantum number (ml) determine?
The orientation of the orbital and can have values between -l and +l.
Do zinc ions have variable oxidation states?
No, they do not have variable oxidation states like other transition metals.
What does the hydrogen emission spectrum consist of?
A series of lines representing the difference in energy between energy levels.
How can reduction be redefined?
As a decrease in oxidation number.
Give examples of monodentate ligands.
Fluoride (F-), Bromide (Br-), Chloride (Cl-), Cyanide (CN-), Hydroxide (OH-), Water (H2O), Ammonia (NH3).
How do heterogeneous catalysts generally work?
Reactants are adsorbed onto the surface of the catalyst at active sites, enhancing their reactivity.
What happens when a photon is absorbed or emitted?
Energy is gained or lost by electrons within the substance.
What shape do p orbitals have?
Dumbbell shaped.
What is the role of compounds containing metals in high oxidation states?
They are often oxidizing agents.
What is a dative covalent bond?
A bond where both electrons are donated by one of the atoms.
What do bidentate ligands do?
They donate two pairs of electrons to the central atom.
What determines the color of a transition metal compound?
The complementary color of the absorbed light.
What type of spectroscopy is used for colorless compounds absorbing energy in the ultraviolet part of the spectrum?
UV spectroscopy.
What allows intermediate complexes to form in catalysis involving transition metals?
The presence of unpaired d-electrons or unfilled d orbitals.
What does the principal quantum number (n) indicate?
The main energy level for an electron and is related to the size of the orbital.
What is the coordination number in a complex?
The total number of bonds from the ligands to the central transition metal.
What is the ligand name for water?
Aqua.
What is an example of a hexadentate ligand?
EDTA.
What is the ligand name for ammonia?
Amine.
What type of spectroscopy is used for compounds that absorb energy in the visible part of the spectrum?
Visible spectroscopy.
What role do transition metals and their compounds play in reactions?
They can act as catalysts.
Why can transition metals have multiple oxidation states?
Because the 3d subshells have energy levels close to that of the 4s subshell.
What is the spectrochemical series?
It is the order of ligands based on their ability to split d orbitals.
What is the ligand name for carbon monoxide?
Carbonyl.
What are monodentate ligands?
Ligands that donate one pair of electrons to the central atom.
What is the significance of changing oxidation states in catalysis?
It provides pathways with lower activation energies compared to the uncatalyzed reaction.
What are strong field ligands?
Ligands that cause a large difference in energy between subsets of d orbitals.
What happens when the wavelength of one or more colors is absorbed?
The colors on the opposite side of the color wheel are transmitted.
What does colorimetry help determine?
The concentration of a colored substance in solution.
What happens to electrons in Atomic Absorption Spectroscopy (AAS)?
Electrons are promoted to higher energy levels by absorbed radiation.
They excite the electrons within atoms, leading to photon emission.
What occurs when energy is transferred to atoms?
Electrons may be promoted to higher energy levels, becoming excited.
As the electrons return to their ground state, they release a photon of light
What causes the lines in the hydrogen emission spectrum?
Electrons falling from higher energy levels to their ground state.
