Covalent Bonding Flashcards
Covalent bond
a chemical bond that involves the electrostatic attraction of a shared pair of electrons and two nuclei
Ionic bond
a chemical bond that involves the electrostatic attraction of cation and an anion
molecular covalent
atoms of the different elements are held together in molecules by covalent bonds
covalent network
a chemical compound (or element) in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material (no fixed chemical formula, but a fixed ratio of elements)
metallic bonding
a chemical bond that involves the electrostatic attraction of a metal cation and a sea of delocalized electrons
electrostatic attraction
when two particle types have opposite charge and there is mutual attraction.
Electronegativity
a measure of an atom’s ability to attract shared electrons to itself
Molecule
a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction
Lewis formula
structures that show the connectivity, or bonding sequence of the atoms, indicating single, double, or triple bonds
Bonding electrons
electrons involved in chemical bonding
Lone pairs
a pair of valence electrons that are not shared with another atom in a covalent bond
Expanded Octets
When atoms contain more than eight electrons in their valence shell, they are said to be hypervalent, only elements in row three and below can be hypervalent
Electron deficient
An electron-deficient compound is one in which the central atom’s octet is incomplete due to a lack of electrons. Boron and Beryllium are the examples you need to know.
Polyatomic ion
molecular ions composed of two or more atoms bonded by covalent bonds and acting as a single unit, but unlike molecules, they have a net charge on them.
You need to know: ammonium, hydroxide, nitrate, hydrogencarbonate, carbonate, sulfate and phosphate.
Octet rule
the tendency of atoms to prefer to have eight electrons in the valence shell
Bond order
the number of bonding pairs of electrons between two atoms
single bond
a chemical bond between two atoms involving two valence electrons
double bond
a chemical bond between two atoms involving four valence electrons
triple bond
a chemical bond between two atoms involving six valence electrons
coordinate bond
a covalent bond (a shared pair of electrons) in which both electrons come from the same atom
VSEPR
Valance shell electron pair repulsion theory, used to find molecular and electron domain geometries
electron domain
the number of lone pairs or bond locations around a particular atom in a molecule
bonding domain
an electron domain involved in bonding
non-bonding domain
an electron domain with non-bonding or lone pair electrons
molecular geometry
the three dimensional shape of a molecule, found using the number of bonding domains in a specific electron domain geometry
electron domain geometry
the three dimensional geometry of all electron domains in a molecule (both lone pairs and bonds)
polarity
Unequal distribution of charge. Bonds can be polar and molecules can be polar- the Prescence of a polar bond does not mean a molecule is polar (this depends on the molecular geometry)
bond polarity
unequal sharing of electrons in a bond, due to a difference in electronegativity (<0.4 non-polar bond, 0.4-1.8 polar bond, >1.8 ionic bond).
pure covalent bond
equal sharing of electrons in a bond (electronegativity difference is 0)
non-polar covalent bond
near equal sharing of electrons in a bond (electronegativity difference is >0 but <0.4)
polar covalent bond
unequal sharing of electrons in a bond (electronegativity difference is between 0.4 and 1.8)
dipole moment
a measurement of the separation of two opposite electrical charges.
giant covalent
All atoms in a giant covalent structure are bonded by strong covalent bonds, and are arranged in crystal lattices. Their entire structure is repetitions of uniform arrangement of atoms. ex: diamond, graphite and silicon dioxide
allotrope
one or more forms of a chemical element that can exist in the same physical state
diamond
a giant covalent structure. in which: each carbon atom is joined to four other carbon atoms by strong covalent bonds. the carbon atoms form a regular tetrahedral network structure.
graphite
a giant covalent structure in which: each carbon atom forms three covalent bonds with other carbon atoms. the carbon atoms form layers of hexagonal rings. there are no covalent bonds between the layers.
graphene
a single layer of graphite
carbon nano-tubes
a network structure of carbons. two of the bonds are single, and one is double. The carbon atoms, in this case, bond to only three other carbon atoms, and are arranged in a hexagonal pattern.
buckminsterfullerene
spherical carbon allotropes where 60 atoms are assembled in pentagons and hexagons, in a geometry similar to a soccer ball. Their cage structure and cause the formation of a displaced electron cloud that allows these molecules to act as charge transfer complexes.
silicone dioxide
giant covalent structure with a similar structure to diamond.
intermolecular forces
the force that mediates interaction between molecules
van der waals forces
a general term used to define the attraction of intermolecular forces between molecules. There are two kinds of Van der Waals forces: weak London Dispersion Forces and stronger dipole-dipole forces
London dispersion forces
London dispersion forces are the weakest intermolecular force. Present in all molecules. Defined as a temporary attractive force due to the formation of temporary dipoles in a nonpolar molecule.
Dipole-dipole foces
attractive forces between the positive end of one polar molecule and the negative end of another polar molecule. second weakest IMF.
Hydrogen bonding
a special type of dipole-dipole attraction when a hydrogen atom bonded to a strongly electronegative atom exists in the vicinity of another electronegative atom with a lone pair of electrons. Strongest IMF
Induced dipole
a weak attraction that results when the approach of an ion induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species.
polarizability
the tendency of matter, when subjected to an electric field, to acquire an electric dipole moment in proportion to that applied field.
Paper chromatography
a technique used to separate and analyze a mixture. Simple paper chromatography, for example, can be used to separate a color mixture. The stationary phase is formed by the filter paper, which has a thin layer of water trapped on it.
chromatogram
essentially the output of a chromatography run
resonance structure
a set of two or more Lewis Structures that collectively describe the electronic bonding of a single polyatomic species including fractional bonds and fractional charges
delocalization
happens when electric charge is spread over more than one atom.
benzene
A six carbon ring molecule stabilized by resonance.
aromatic
hydrocarbons, organic compounds that consist exclusively of the elements carbon and hydrogen in ring structures
resonance energy
the difference between the electronic energy of a real (conjugated) molecule and a hypothetical structure with localized bonds.
formal charge
a charge assigned to an atom under the assumption that all electrons in bonds are shared equally
valance bond theory
theory that covalent bonds are the result of overlapping half-filled atomic orbitals.
sigma bonds
strongest covalent bond, formed from the head on overlap of two orbitals along the bond axis
pi bonds
covalent bond formed by the side-to-side overlap of p orbitals perpendicular to the bond axis
bond axis
the imaginary straight line that connects the nuclei of atoms bonded to each other in a molecule
hybridization
the concept of mixing atomic orbitals to form new hybrid orbitals (aka s and p hybrids)
hybrid orbitals
During the process of hybridization, the atomic orbitals of comparable energies are mixed together and mostly involves the merging of two ‘s’ orbitals or two ‘p’ orbitals or the mixing of an ‘s’ orbital with a ‘p’ orbital, as well as ‘s’ orbital with a ‘d’ orbital.
electron promotion (hybridization)
electrons moving up an energy level (s to p)
sp3
When one ‘s’ orbital and 3 ‘p’ orbitals belonging to the same shell of an atom mix together to form four new equivalent orbitals
sp2
when one s and two p orbitals of the same shell of an atom mix to form 3 equivalent orbitals.
sp
when one s and one p orbital in the same main shell of an atom mix to form two new equivalent orbitals
