chem.
Terms
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- chemical bond
- a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together
- covalent bonding
- the sharing of electron pairs between two atoms
- ionic bonding
- chemical bonding that results from the electrical attraction between large numbers of cations and anions
- nonpolar-covalent bond
- a covalent bond in which the bonding electrons are shared equally by the bonded atoms resulting in a balanced distribution of electrical charge
- polar
- when bonds have an uneven distribution of charge
- polar-covalent bond
- a covalent bond in which the bonded atoms have an unequal attraction for the shared electrons
- bond length
- average distance between two bonded atoms at their minimum potential energy
- bond energy
- the energy required to break a chemical bond and form neutral isolated atoms
- molecule
- a neutral group of atoms that are held together by covalent bonds
- molecular compound
- a chemical compound whose simplest units are molecules
- chemical formula
- indicates the relative numbers of atoms of each kind in chemical compound by using atomic symbols and numerical subscripts
- molecular formula
- shows types and numbers of atoms combined in singly molecule of a compound
- octet rule
- chemical compounds tend to form so that each atom by gaining, losing, or sharing electrons has an octet of electrions in its highest occupied energy level
- exceptions to the octet rule
- hydrogen forms bonds surrounded by only two electrons. Boron has only six electrons. Other elements can be surrounded by more than eight electrons when combined with highly electronegative elements like fluorine, oxygen, and chlorine. In these cases of EXPANDED VALENCE, bonding involves electrons in d, s and p orbitals
- electron-dot notation
- electron-configuration notation in bonding that belongs exclusively to one atom
- unshared pair/lone pair
- pair of electrons not involved in bonding that belongs exclusively to one atom
- Lewis structures
- formulas in which atomic symbols represent nuclei and inner-state electron pairs in covalent bonds and dots adjacent to only one atomic symbol representing unshared electrons
- structural formula
- indicates kind, number, arrangement, and bonds but not the unshared pairs of the atoms in a molecule
- single bond
- covalent bond produced by the sharing of one pair of electrons between two atoms
- double bonds
- covalent bond produced by the sharing of two pairs of electrons between two atoms
- triple bonds
- covalent bond produced by the sharing of three pairs of electrons between two atoms
- resonance
- refers to bonding in molecules or ions that cannot be correctly represented by a single Lewis structure
- ionic compound
- composed of positive and negative ions that are combined so that the numbers of positive and negative charged are equal
- formula unit
- the simplest collection of atoms from which an ionic compound's formula can be established
- crystal lattice
- in an ionic crystal, ions minimize their potential energy by combining in an orderly arrangement
- lattice energy
- the energy released when one mole of an ionic crystalline compound is formed from gaseous ions
- polyatomic ion
- a charged group of covalently bonded atoms
- metallic bonding
- the chemical bonding that results from the attraction between the metal atoms and the surrounding sea of electrons
- metallic properties
- they are high electrical and thermal conductors due to the freedom of electrons to move in a network of metal atoms. they also contain many orbitals separated by extremely small energy differences which allow absorption of light. the other two characteristics are:
- 1] malleability
- the ability of a substance to be hammered or beaten into sheets
- 2] ductility
- the ability of substance to be drawn, pulled, or extruded through a small opening to produce a wire
- heat of vaporization
- metallic bond strength caries with the nuclear charge of the metal atoms and the number of electrons in a metal's electron sea. both of these factors are reflected in a metal's heat of vaporization. when a metal is vaporized, the bonded atoms in the normal state are converted to individual metal atoms in the gaseous state. The amount of heat required to vaporize the metal is a measure of the strength of the bonds that hold the metal together.
- molecular geometry
- the uneven distribution of molecular charge; strongly influences the forces that act between molecules in liquids and solids
- VSEPR theory
- stands for "valence-shell, electron-pair repulsion." states that repulsion between the sets of valence-level electrons surrounding an atom causes these sets to be oriented as far apart as possible
- hybridization
- the mixing of two or more atomic orbitals of similar energies on the same atom to produce new orbitals of equal energies
- hybrid orbitals
- orbitals of equal energy produced by the combination of two or more orbitals on the same atom
- intermolecular forces
- the forces of attraction between molecules
- dipole
- created by equal but opposite charges that are separated by a shore distance
- dipole-dipole forces
- the forces of attraction between polar molecules
- hydrogen bonding
- the intermolecular force in which a hydrogen atom that is bonded to a highly electronegative atom is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule
- London dispersion forces
- intermolecular attractions resulting from the constant motion of electrons and the creation of instantaneous dipoles
- if the difference in electronegativities to find if a bond is ionic or covalent is 0-0.3 or 0%-5%, than it is...
- a non-polar covalent bond
- if the difference in electronegativies to find if a bond is ionic or covalent is from 0.3-1.7 or 5%-50%, then it is...
- a polar-covalent bond
- if the difference in electronegativies to find if a bond is ionic or covalent is from 1.7-3.3 or 50%-100% then it is...
- an ionic bond