Chapter 1 Flashcards
The chemistry of compounds that contain the element carbon
Organic chemistry
A compound that doesn’t contain carbon
Inorganic
Organic compounds that came from living organisms, and only living things could synthesize organic compounds through intervention of a vital force
Vitalism
Elements combined in different proportions
Compounds
Made up of atoms
Elements
Consists of a nucleus containing protons and neutrons surrounded by a cloud of electrons
Atom
A number equal to the number of protons in its nucleus
Atomic number (Z)
Atoms of the same element with different masses because of different amounts of neutrons
Isotopes
A hydrogen atom with one neutron
Deuterium (2H)
A hydrogen atom with 2 neutrons
Tritium (3H)
The outermost shell of electrons that are used in bonding
Valence shell
Electrons in the valence shell
Valence electrons
Bonds formed by the transfer of one or more electrons from one atom to another to create ions; attractive force between oppositely charged ions
Ionic bonds
Bonds formed when atoms share electrons; sharing of electrons between atoms of similar electronegativities to achieve the configuration of a noble gas
Covalent bonds
The tendency for an atom to achieve a configuration where it’s valence shell contains 8 electrons
Octet rule
A measure of the ability of an atom to attract electrons
Electronegativity
Compounds that form only when atoms of very different electronegativities transfer electrons to become ions
Salts (ionic compounds)
Composed of atoms joined exclusively or predominantly by covalent bonds
Molecules
A formula that has lines that show bonding electrons pairs and includes elemental symbols for the atoms in a molecule
Dash structural formula
A bond between two carbon atoms comprised of two electrons shared in a sigma (σ) bond
Carbon-carbon single bond
A representation of a molecule showing electron pairs as a pair of dots or as a dash
Lewis dot structure (electron dot structure)
Bonds comprised of one sigma (σ) bond and two pi (π) bonds
Triple bond
A bond between two carbon atoms comprised of four electrons; two of the electrons are in a sigma bond and two of the electrons in a pi bond
Carbon-carbon double bond
A bond between two carbon atoms comprised of six electrons; two of the electrons are in a sigma bond and four of the electrons are as pairs in each of two pi bonds
Carbon-carbon triple bond
A negative ion
Anion
A positive ion
Cation
A comparison between the number of valence electrons an atom “owns” in a molecule compared with the number of valence electrons it would have as a neutral isolated ion
Formal charge
Different molecules that have the same molecular formula
Isomers
A formula that gives the total number of each kind of atom in a molecule; is a whole number multiple of the empirical formula
Molecular formula
Compounds that have the same molecular formula but that differ in their connectivity (i.e., same molecular formula but have their atoms connected in different ways)
Constitutional isomers
The sequence, or order, in which the atoms of a molecule are attached to each other
Connectivity
A formula that shows how the atoms of a molecule are attached to each other
Structural formula
A chemical formula written using letters of the elemental symbols for the atoms involved, listed in sequence for the connections of the central chain of atoms and without showing the bonds between them
Condensed structural formula
A formula that shows the carbon skeleton of a molecule with lines. The number of hydrogen atoms necessary to fulfill each carbon’s valence is assumed to be present but not written in. Other atoms (e.g., O, Cl, N) are written in
Bond-line formula (skeletal formula)
Structural formulas in which atom symbols are drawn and a line or “dash” represents each pair of electrons (a covalent bond). These formulas show connectivities but don’t represent the true geometries of the species
Dash structural formulas
The angle between two bonds originating at the same atom
Bond angle
A molecular geometry where a central atom is located at the center with four substituents that are located at the corners of a tetrahedron; bond angles are approximately 109
Tetrahedral geometry
A molecular geometry with one atom at the center and three atoms at the corners of an equilateral triangle, called peripheral atoms, all in one place; bond angles are 120
Trigonal planar geometry
A molecular geometry where a central atom is bonded to two other atoms; bond angles are 180
Linear geometry
Lewis structures that differ from one another only in the position of their electrons. A single resonance structure will not adequately represent a molecule. The molecule is better represented as a hybrid of all the resonance structures
Resonance structures (resonance contributors)
These show the direction of electron flow in a reaction mechanism. They point from the source of an electron or electron pair to the atom receiving the electron or electron pair. Double-barbed curved arrows are used to indicate the movement of a pair of electrons; single-barbed curved arrows are used to indicate the movement of a single electron. They are not used to show the movement of atoms
Curved arrows
A calculated model in which regions of higher electron density trend toward red and regions of lower electron density trend toward blue
Electrostatic potential map
A mathematical expression derived from quantum mechanics corresponding to an energy state for an electron, i.e., for an orbital; corresponds to a different energy state for an electron
Wave function (ψ)
Signs, either + or -, that are characteristic of all equations that describe the amplitudes of waves; indicates whether the solution is positive or negative when calculated for a different point in space relative to the nucleus
Phase sign
When wave functions with the same phase sign interact. There is a reinforcing effect and the amplitude of the wave function increases
Constructive interference
When wave functions with opposite phase signs interact. There is a subtractive effect and the amplitude of the wave function goes to zero or changes sign
Destructive interference
A volume of space in which there is a high probability of finding an electron
Orbital
A volume of space about the nucleus of an atom where there is a high probability of finding an electron; plots of ψ2 in three dimensions consisting of s, p, and d orbital shapes
Atomic orbital
A spherical atomic orbital; s orbitals have the quantum number l = 0
s orbital
A set of three degenerate (equal energy) atomic orbitals shaped like two tangent spheres with a nodal plane at the nucleus; p orbitals have the quantum numbers n = 2, l = 1, m = +1, 0, -1
p orbital
Orbitals of equal energy (ex. the three 2p orbitals)
Degenerate orbitals
The principle that states orbitals are filled so that those of lowest energy are filled first
Aufbau principle
The principle that states a max of two electrons may be placed in each orbital but only when the spins of the electrons are paired
Pauli exclusion principle
The rule stating when filling degenerate orbitals (ex. p orbitals) we add one electron to each with their spins unpaired until each of the degenerate orbitals are filled
Hund’s rule
The equilibrium distance between two bonded atoms or groups
Bond length
A fundamental principle that states that both the position and momentum of an electron (or of any object) can’t be exactly measured simultaneously
Heisenberg uncertainty principle
Orbitals that encompass more than one atom of a molecule. When atomic orbitals combine to form molecular orbitals, the number of molecular orbitals that results always equals the number of atomic orbitals that combine
Molecular orbital
Results when two orbitals of the same phase overlap; the energy is lower than the separate orbitals used to create the bonding orbital
Bonding molecular orbital (ψmolec)
Results when two orbitals of opposite phase overlap; the energy is higher than the separate orbitals used to create the anti bonding molecular orbital
Antibonding molecular orbital (ψ*molec)
A mathematical method for arriving at wave functions for molecular orbitals that involves adding or subtracting wave functions for atomic orbitals
LCAO (linear combination of atomic orbitals)
A mathematical (and theoretical) mixing of two or more atomic orbitals to give the same number of new orbitals, called hybrid orbitals, each of which has some of the character of the original atomic orbitals
Orbital hybridization
An orbital that results from the mathematical combination of pure atomic orbitals, such as the combination of pure s and p orbitals in varying proportions to form hybrids such as sp3, sp2, and sp orbitals
Hybrid atomic orbitals
The lowest electronic energy state of an atom or molecule
Ground state
A single bond formed through head-on overlap of atomic orbitals
Sigma (σ) bond
Shows points in space that happen to have the same electron density
Electron density surface
Hydrocarbons whose molecules contain a carbon-carbon double bond
Alkenes
A molecular orbital formed when parallel p orbitals on adjacent atoms overlap
Pi (π) molecular orbital
A molecular orbital whose energy is higher than that of the isolated atomic orbitals from which it’s constructed
Antibonding molecular orbital
A molecular orbital formed by end-on overlap of orbitals on adjacent atoms
Sigma (σ) orbital
Bonds comprised of four electrons: two electrons in a sigma (σ) bond and two electrons in a pi (π) bond
Double bonds
Two objects are superposable if, when one object is placed on top of the other, all parts of each coincide
Superposable
Compounds with the same molecular formula that differ only in the arrangement of their atoms in space
Stereoisomers
Diastereomers that differ in their stereochemistry at adjacent atoms of a double bond or on different atoms of a ring
Cis-trans isomers
Hydrocarbons in which two carbon atoms share three pairs of electrons between them, and are bonded by a triple bond
Alkynes
The equilibrium distance between two bonded atoms or groups
Bond lengths
A method of predicting the geometry at a covalently bonded atom by considering the optimum geometric separation between groups of bonding and non bonding electrons around the atom
Valence shell electron pair repulsion (VSEPR) model
Electrons shared in covalent bonds
Bonding pairs
Electrons that are unshared
Non bonding pairs (unshared pairs or lone pairs)
Consists of 3 bonding pairs and 1 non bonding pair
Trigonal pyramidal geometry
Consists of 2 or 4 bonding pairs
Linear geometry
Consists of 3 bonding pairs
Trigonal planar geometry
Consists of 4 bonding pairs
Tetrahedral geometry
Consists of 2 bonding and 2 non bonding pairs
Angular/bent geometry
