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Covalent Bonding and Molecular Structure
Some terms and definitions related to the study of covalent bonding, molecular shapes, hybridization of atomic orbitals, and bond order.
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Chemistry
02/06/2013

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Term
Bond Length
Definition
The optimum distance between nuclei where the net attractive forces are maximized.
Term
Structural Formula
Definition
A formula for a molecule that shows specific bonds between atoms.
Term
Chemical Formula
Definition
Molecular formula. Gives the number and type of each element in the molecule.
Term
Bond Dissociation Energy
Definition
The amount of energy that must be supplied when a bond breaks or the amount of energy released when a bond is formed.
Term
Electronegativity
Definition
The ability of an atom to attract shared electrons in a covalent bond. Increases from left to right along a period of the periodic table. Increases from bottom to top of a group on the periodic table.
Term
Electron-Dot Structure
Definition
Lewis Structure. A structure that represents an atom's valence electrons by dots and indicates by the placement of dots how the valence electrons are distributed in a molecule.
Term
Lone Pair
Definition
Nonbonding pair; A pair of valence electrons assigned to an atom in a Lewis structure that are not involved in bonding.
Term
Bonding Pair
Definition
Shared valence electrons in a dot structure that make up bonds between atoms
Term
Formal Charge
Definition
The number of valence electrons for a free atom minus the number of valence electrons assigned to a bonded atom.
Term
Polar Covalent Bond
Definition
A covalent bond in which the bonding electrons are shared unequally.
Term
Nonpolar Covalent Bond
Definition
A covalent bond in which the bonding electrons are shared equally.
Term
Valence-Shell Electron-Repulsion (VSEPR) Model
Definition
A model for predicting the approximate shape of a molecule.
Term
Charge Cloud
Definition
A cloud of electrons assigned to an atom in a molecule and used to determine the approximate shape of the molecule. A single charge cloud could be one lone pair, one single bond, one double bond, or one triple bond.
Term
Bond Angle
Definition
The angle at which two adjacent bonds intersect.
Term
Valence Bond Theory
Definition
A theory that visualizes the orbital picture of how electron pairs are shared in a covalent bond.
Term
Sigma Bond
Definition
A bond that forms from the head-on overlap of atomic orbitals. Always the first bond to form between two atoms in a molecule.
Term
Pi Bond
Definition
A bond that forms from the parallel overlap of two p orbitals. Only present in double (1 pi) or triple bonds (2 pi).
Term
sp2 hybridized orbital
Definition
An atomic orbital formed by the hybridization of an s orbital with two p orbitals.
Term
sp hybridized orbital
Definition
An atomic orbital formed by the hybridization of an s orbital with one p orbitals.
Term
sp3 hybridized orbital
Definition
An atomic orbital formed by the hybridization of an s orbital with three p orbitals.
Term
Molecular Orbital
Definition
A wave function whose square gives the probability of finding an electron within a given region of space in a molecule.
Term
Atomic Orbital
Definition
A wave function whose square gives the probability of finding an electron within a given region of space in an atom.
Term
Molecular Orbital (MO) Theory
Definition
A quantum mechanical description of bonding in which electrons occupy molecular orbitals that below to the entire molecule rather than to an individual atom.
Term
Bonding Molecular Orbital
Definition
A molecular orbital that is lower in energy than the atomic orbitals from which it is derived.
Term
Anti-Bonding Molecular Orbital
Definition
A molecular orbital that is higher in energy than the atomic orbitals from which it is derived.
Term
Bond Order
Definition
The number of electron pairs between atoms. (# of bonding electrons - # of antibonding electrons) divided by two.
Term
Formal Charge Equation
Definition
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Term
Alkali Metals
Definition
Group 1A elements. Rapidly react with water to form alkaline products. Soft, silvery metals. Never found in a pure state in nature.
Term
Alkaline Earth Metals
Definition
Group 2A elements. Lustrous, silvery metals. Less reactive than the Group 1A elements. Never found in a pure state in nature.
Term
Halogens
Definition
Group 7A elements. Found in nature only in combination with other elements, such as salts.
Term
Noble Gases
Definition
Group 8A elements. Colorless gases with very low or no chemical reactivity.
Term
Calorie
Definition
1000 calories or 1 kilocalorie or 4.184 kJ
Term
calorie
Definition
a unit of energy measured as the amount of energy required to increase the temperature of 1 g of water by 1 degree Celcius
Term
Joule
Definition
SI unit of energy
Term
Rule #3 for Rounding
Definition
If the first digit you remove is a 5 and there are nonzero digits following, round up.
Term
Rule #4 for Rounding
Definition
If the first digit you remove is a 5 with nothing or a 0 following, round down.