ap chem unit 2 vocab 💧

ionic bond

a bond formed when oppositely charged ions attract one another by electrostatic forces

ionic compound

result of an ionic bond, and in a solid forms a lattice of alternating cations and anions

covalent bond

bonding where atoms share some of their electrons, which have lower potential energy than they do in isolated atoms

molecular compounds

covalently bonded compounds

chemical formula

a formula that indicates the elements present in a compound and the relative number of atoms or ions of each element

empirical formula

gives the relative number of atoms of each element in a compound

molecular formula

gives the actual number of atoms of each element in a compound

structural formula

uses lines to represent covalent bonds and shows how atoms in a molecule connect or bond to each other

ball-and-stick molecular model

a model that represents atoms as balls and chemicals bonds as sticks

space-filling molecular model

a model where atoms fill the space between each other to more closely represent our best estimate for how a molecule might appear if scaled to a visible size

atomic elements

elements that exist in nature with single atoms as their basic units

molecular elements

elements that do not normally exist in nature with single elements as their basic units

formula unit

the smallest, electrically neutral collection of ions

polyatomic ion

an ion composed of two or more atoms

systematic names

names for chemicals that can be derived from its chemical formula and vice versa

binary compounds

compounds that contain only two different elements

oxyanions

anions containing oxygen and another element

hydrates

ionic compounds that contain a specific number of water molecules associated with each formula unit

formula mass

the average mass of a molecule (or formula unit) of a compound

mass percent composition / mass percent

an element’s percentage of the compound’s total mass

Lewis model

a bonding model where valence electrons are represented as dots and we draw Lewis electron-dot structures to depict molecules

Lewis electron-dot structures

structures that can be used to predict whether a particular set of atoms will form a stable molecule and what that molecule will look like

metallic bonding

a type of chemical bonding where valence electrons are pooled in an electron sea and the positively charged metal atoms are attracted, holding the metal together

Lewis symbol

the representation of valence electrons of main-group elements as dots surrounding the element symbol

octet

eight dots in a Lewis structure representing eight valence electrons

duet

two dots in a Lewis structure representing two valence electrons

chemical bond

the sharing or transfer of electrons to attain stable electron configurations for the bonding atoms

octet rule

the stable configuration must be attained for bonding to occur, which is usually eight electrons in the outermost shell

lattice energy

the energy associated with the formation of a crystalline lattice of alternating cations and anions from gaseous ions

Born-Haber cycle

a hypothetical series of steps that represents the formation of an ionic compound from its constituent elements

bonding pair

a shared pair of electrons

lone pair / nonbonding electrons

a pair of electrons that is associated with only one atom and is therefore not involved in bonding

double bond

the type of bonding that occurs when two atoms share two electron pairs

triple bond

the type of bonding that occurs when two atoms share three electron pairs

polar covalent bond

a covalent bond intermediate in nature between a pure covalent bond and an ionic bond

electronegativity

the ability of an atom to attract electrons to itself in a chemical bond, resulting in polar and ionic bonds

dipole moment

occurs any time there is a separation of positive and negative charge

percent ionic character

the ratio of a bond’s actual dipole moment to the dipole moment it would have if the electron were completely transferred from one atom to the other, multipled by 100

resonance structure

one of two or more Lewis structures that have the same skeletal formula, but different electron arrangements

resonance hybrid

the actual, intermediate structure of two resonance structures of a molecule

formal charge

a fictitious charge assigned to each atom in a Lewis structure that helps us to distinguish among competing Lewis structures

free radicals

molecules and ions with an odd number of electrons in their Lewis structures

bond energy

the energy required to break 1 mole of the bonds in the gas phase of a chemical

bond length

the average length of a bond between two particular atoms in a large number of compounds

valence shell electron pair repulsion (VSEPR) theory

a theory based on the simple idea that electron groups repel one another through coulombic forces

electron groups

lone pairs, single bonds, multiple bonds, or even single electrons

linear geometry

the geometry of a molecule determined by having two electron groups about the central atom and assuming 180° bond angles

trigonal planar geometry

the geometry of a molecule determined by having three electron groups about the central atom and assuming 120° bond angles

tetrahedal geometry

the geometry of a molecule determined by having four electron groups about the central atom and assuming 109.5° bond angles

trigonal bipyramidal geometry

the geometry of a molecule determined by having five electron groups about the central atom and assuming equatorial positions of 120° bond angles and axial positions of 90° bond angles

octahedral geometry

the geometry of a molecule determined by having six electron groups about the central atom and assuming 90° bond angles

electron geometry

the geometrical arrangements of electron groups

molecular geometry

the geometrical arrangements of atoms

trigonal pyramidal geometry

the geometry of a molecule with tetrahedral electron geometry and one lone pair

bent geometry

the geometry of a molecule with tetrahedral electron geometry and two lone pairs

seesaw geometry

the geometry of a molecule with trigonal bipyramidal electron geometry and one lone pair

T-shaped geometry

the geometry of a molecule with trigonal bipyramidal electron geometry and two lone pairs

square pyramidal geometry

the geometry of a molecule with octahedral electron geometry and one lone pair

square planar geometry

the geometry of a molecule with octahedral electron geometry and two lone pairs

valence bond theory

a theory that states that electrons reside in quantum-mechanical orbitals localized on individual atoms

hybridization

a mathematical procedure in which the standard atomic orbitals are combined to form new atomic orbitals that correspond more closely to the actual distribution of electrons in chemically bonded atoms

hybrid orbitals

new atomic orbitals in hybridization that are still localized on individual atoms, but have different shapes and energies from standard atomic orbitals

pi bond

the resulting bond when p orbitals overlap side-by-side

sigma bond

the resulting bond when orbitals overlap end to end