Term
|
Definition
• All atoms lie in a straight line.
• Bond angle: XAX = 180°.
180
g
• Examples: diatomic species, HCN, CO2 |
|
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Term
| Trigonal Planar(planar triangular |
|
Definition
• X atoms at the vertices (corners) of a triangle.
• Each X atom is bonded to atom A located at the center of the
triangle.
• All four atoms are in a single plane.
• Bond angle: XAX = 120°.
• Examples: BF3, CO3 2 |
|
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Term
|
Definition
• Four sided pyramid with triangular faces
• X atom at each of the 4 vertices.
• Each X atom is bonded to atom A located at the center of
pyramid.
• Bond angle: XAX = 109.5°.
• First 3-dimensional geometry X
• Examples: CH4, NH4
+ |
|
|
Term
| trigonal bipyramidal geometry |
|
Definition
Planar triangular geometry (AX3) with one additional X atom
above the plane and the other below the plane.
• Each X atom is bonded to atom A located at the center of planar
triangle.
• Three Equatorial Bonds: Bonds between atom A and X
atoms (Xeq) at the vertices of the triangle.
• Two Axial Bonds: Bonds between atom A and X atoms (Xax)
above/below the planar triangle.
• Bond angles:
• XeqAXeq = 120°.
Xax
eq eq 90
• XeqAXax = 90°.
• XaxAXax = 180°. A
X
Xeq
Xeq
120
5
• Examples: PF5 |
|
|
Term
|
Definition
• Four X atoms at the vertices of a square, and atom A at the
center of the square.
• Four Equatorial Bonds: Bonds between atom A and X
atoms (Xeq) at the vertices of the square.
• One X atom above and another below the plane of the square.
• Two Axial Bonds: Bonds between atom A and X atoms
(Xax) above/below the plane of the square.
• Bond Xax
Xeq
Xeq
angles:
• XeqAXeq = 90°.
• XeqAXax = 90°.
X AX 180°
A
X
Xeq
eq
Xeq
90
• XaxAXax = 180°.
• Examples: SF6 |
|
|
Term
3 types of valence electron repulsions?
list in terms of repulsive force |
|
Definition
- lone pair--lone pair*strong
-lone pair--bond pair*intermediate
-bond pair--bond pair*weak |
|
|
Term
| region of high electron density (hed); identify individual regions of hed |
|
Definition
electron geometries
-Each single, double, or triple bond is 1 region of hed.
• each lone pair is 1 region of hed.
• each unpaired electron (odd # of valence electrons) is 1 region of
hed.
4) If more than arrangement of lone and bonding electron pairs is
possible, select the arrangement which minimizes lone pair
repulsions.
• Trigonal bipyramidal: Place lone pairs in equatorial positions
before axial positions.
• Octahedral: Place the first lone pair in any one of the six
equivalent regions of hed. Place the second lone pair opposite the
first lone pair.
5) The molecular geometry (structure) is the arrangement of only atoms
around the central atom, and is given in the following table. |
|
|
Term
| the most stable arrangement (fundamental geometry) associated with various numbers of regions of hed |
|
Definition
2 Linear
3 Trigonal Planar
4 Tetrahedral
5 Trigonal Bipyramidal
6 Octahedral |
|
|
Term
| electronic geometry vs. molecular geometry |
|
Definition
| molecular is only ATOMS around the central atom. |
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Term
|
Definition
A measure of the polarity of a molecule
Scheme #1
• Electron rich region has a partial negative charge ( -).
• Electron poor region has a positive charge(x+ ). |
|
|
Term
| How to figure out if an atom is polar or nonpolar |
|
Definition
if dipole = 0, nonpolar molecule
if dipole > 0, polar molecule
-if all regions around the central atom are identical, the bond is nonpolar.
-if regions of hed are non identical then the atom is polar. |
|
|
Term
|
Definition
Theory of covalent bonding which
describes a chemical bond as being formed by the overlap of:
1) Two atomic orbitals (s, p, d, f…), one from each atom of the
bond.
2) Two hybrid orbitals.
3) An atomic orbital and a hybrid orbital. |
|
|
Term
|
Definition
Orbitals formed by the mathematical mixing of
two or more atomic orbitals of a central atom. |
|
|
Term
|
Definition
A bond formed by the overlap of atomic or hybrid
orbitals in which the shared electron density is concentrated directly
along the internuclear axis between the two nuclei involved in
bonding.
• All single bonds are sigma bonds. |
|
|
Term
|
Definition
A bond formed by the sideways overlap of a pair of
unhybridized p orbitals, which concentrates electron density in
two separate regions that lie on opposite sides of the internuclear
axis between the two nuclei involved in bonding. |
|
|
Term
| a double bond in terms of sigma and pi bond |
|
Definition
|
|
Term
| a triple bond in terms of sigma and pi |
|
Definition
|
|
Term
| single bond in terms of sigma and pi |
|
Definition
| all single bonds are sigma |
|
|
Term
|
Definition
| base unit of amount of a chemical substance |
|
|
Term
|
Definition
|
|
Term
|
Definition
| mole ratio of atoms within a compound |
|
|
Term
|
Definition
the mole ratio of compounds in a chemical reaction
-Coefficients of a balanced chemical reaction supply the mole
ratios by which reactants and products are related |
|
|
Term
Reactants are consumed.
• Products are formed.
• There is a transfer of energy |
|
Definition
| 3 things that happen in any chemical reaction: |
|
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Term
|
Definition
Study of the changes in energy and
transfer of energy that accompany chemical and physical
processes. |
|
|
Term
|
Definition
the capacity to do work
1 cal=4.184 J |
|
|
Term
|
Definition
|
|
Term
|
Definition
A measure of the internal energy that is
absorbed or transferred from one body to another. |
|
|
Term
| heat measures internal energy absorbed or transfered from one body to the other, temperature is simply a measure of an objects hotness or coldness |
|
Definition
| difference in heat and temperature |
|
|
Term
|
Definition
| the total kinetic energy and potential energy of all the molecules of an object |
|
|
Term
|
Definition
energy of motion
equation=? |
|
|
Term
|
Definition
energy possessed by an object due to its position or composition.
-magnet, rubber band stretching |
|
|
Term
1) transferring energy only in the form of heat.
2) Transferring energy only in the form of work.
3) Transferring energy as a mixture of work and heat. |
|
Definition
| (delta E) 3 ways to change the internal energy of a system |
|
|
Term
| First law of thermodynamics |
|
Definition
The total amount of energy in the
universe is constant. OR….
• Energy can be converted from one form to another but cannot be
created or destroyed. |
|
|
Term
|
Definition
substance under investigation
chemical reaction happening inside the beaker |
|
|
Term
|
Definition
rest of universe
the beaker and outside the beaker |
|
|
Term
|
Definition
|
|
Term
| number of moles of each substance;physical state of each substance;temperature;pressure;volume |
|
Definition
| 5 variables required to describe the thermodynamic state of a system |
|
|
Term
|
Definition
A Property of a system that depends only on the
state of the system, and not how the system came to be in that state. |
|
|
Term
|
Definition
cannot measure this but can measure change of it.
a state function
H=U+PV |
|
|
Term
| enthalpy change (delta H) |
|
Definition
The change in the heat content of a system that
accompanies a process which occurs at a constant pressure.
• Heat is commonly designated “q”… qp heat at a constant pressure. |
|
|
Term
|
Definition
| system absorbs heat from surroundings |
|
|
Term
|
Definition
| system releases heat to surroundings |
|
|
Term
|
Definition
Experimental technique
used to measure the heat released or
absorbed during a reaction. |
|
|
Term
|
Definition
device used to measure the
heat released/absorbed during a reaction |
|
|
Term
|
Definition
| amount of heat gained by calorimeter;aka calorimeter constant |
|
|
Term
|
Definition
Chemical reaction and the corresponding H
value. |
|
|
Term
1) CH3CO2H(aq) + NaOH(aq) NaCH3CO2(aq) + H2O(l) H = -56.8 kJ/mol
2) CH3CO2H(aq) + NaOH(aq) NaCH3CO2(aq) + H2O(l) + 56.8 kJ/mol |
|
Definition
2 ways to write thermochemical reaction
examples: |
|
|
Term
Pressure=1 atm
Temp=25 Celcius
Delta H degrees |
|
Definition
| what is the temperature,symbol, and pressure corresponding to standard conditions |
|
|
Term
|
Definition
the most stable state of a substance at standard conditions
i.e.H2O: most stable state at 1 atm and 25°C is H2O(l).
• NaCl: most stable state at 1 atm and 25°C is NaCl(s). |
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