Chemistry (Unit1, 2)
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Chemistry (Unit1, 2) - Leaderboard
Chemistry (Unit1, 2) - Details
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38 questions
🇬🇧 | 🇬🇧 |
The net nuclear charge/net attraction experienced by an electron to the nucleus, taking into account all electronic repulsions. | Effective nuclear charge |
6.63 x 10^-34 Js | Planck's constant |
E=hv where E is enery h is Planck's constant v is frequency | Bohr's equation |
The quantum of EM action that relates the photon's energy to its frequency. Units are Js. | Planck's constant |
Why is a C-C bond strong? | 1) it is a covalent bond meaning there are shared electrons 2) the bond is not polarized, meaning that it is less susceptible to heterolytic fission 3) the BDE for homolysis is 84kcal/mol |
6.02 x 10^23 | Avogadro's number |
The absorption of EM energy at a frequency such that the photon energy is equal to the quantum excitation energy of the absorbing system. | Resonance Absorption |
Use of UV-vis spectroscopy | Measuring the the electron transitions that occur in the UV-vis region of the EMS. |
Use of IR spectroscopy | Measuring the vibrational and rotational transitions that occur in the IR region of the EMS. |
Antibonding orbital | A type of molecular orbital that weakens the bond between two atoms and raises the energy of the molecule as compared to two separated atoms. There may be one or more nodes in the bonding region between the nuclei. |
Alkane | Molecule that will not absorb in the UV-vis region of EMS |
Π→π*, n→π*, n→σ* | Electronic transitions that normally produce absorption in the UV-vis region. |
Beer-Lambert's Law | The degree of absorption of light at a given wavelength by an absorbing compound in a non-absorbing solvent depends on the concentration of the compound and the path length of the radiation. (The concentration of a chemical solution is directly proportional to its absorption of light) |
Beer-lambert's Law | A= -log(T) = Σcl |
Molar absorptivity constant | A measurement of how strongly a chemical species attenuates light at a given wavelength |
Chromophore | The moiety that causes a conformational change of the molecule when hit by light, and consists system of extensively conjugated pi-electrons. |
Enthalpy Change | Energy of products - energy of the reactants ΔH = Hp - Hr |
Endothermic reaction | Involves bond breaking Energy of the products is greater than that of the reactants Temperature of the reactant vessel decreases (colder) |
Exothermic reacrion | Involves bond making Energy of products is less than that of the reactants Heat is given off from, the reaction vessel to the environment |
Activation energy | The initial energy absorbed by reactant molecules, causing bond to lengthen and and weaken to form an activated complex or transition state. In this complex, the energy state is high and the complex is highly unstable. |
Standard enthalpy of formation (ΔHf) | The heat change when when one mole of a substance is formed from its constituent elements in their normal states under standard conditions |
Standard enthalpy of combustion | The heat change when i mole of a substance is completely burnt in oxygen under standard conditions. |
Standard enthalpy of neutralization | The enthalpy change when an acid reacts with a base to form 1 mole of water under standard conditions |
Standard enthalpy of atomization | The heat change when 1 mole of gaseous atoms is formed from the element under standard conditions. |
1st Ionization energy | The enthalpy change when 1 mole of gaseous atoms is converted to gaseous ions with a singe positive charge |
1 electron affinity | The enthalpy change when 1 mole of gaseous atoms is converted to gaseous ions with a single negative charge |
8.314 J/K mol | Universal Gas constant (R) |