HL Chem - 11 - Topic 4 & 14

Qualitative data

non-numerical data obtained from observations that are made during an experiment

Ionic bond

the transfer of one or more electrons from the outer shell of one atom to the outer shell of another atom; electrostatic attraction between positive and negative ions

Anions

negative ions

Cation

formed when an atom has more protons than electrons and becomes positively charged

Electrostatic attraction

the force of attraction between opposite charges

Ionic compound

consists of a metal and non-metal element

Octet rule

atoms are more stable with the configuration of a noble gas

lattice structure

the ions that make up an ionic compound that are arranged in a regular crystalline structure

Polyatomic ions

ions that consist of more than one ion

Volitility

a term used to describe how easily a substance evaporates

Brittle

ionic compounds as they tend to shatter when a force is applies

Covalent bond

the electrostatic attraction between positively charges nuclei and shared pairs of bonding electrons

Bond length

the distance between the nuclei of the bonded atoms

Bond strength

the amount of energy needed to break the bond between atoms

coordinate covalent bond

atom's electrons bonding within itself

Dimer

larger molecule composed of two identical smaller molecules that can be linked by coordinate covalent bonds or by hydrogen bonds

Bond order

the number of bonds between a pair of atoms

Non polar covalent bonds

bonds that occur between atoms that have no difference in electronegativity

Polar covalent bonds

bonds that occur between atoms that have a difference in electronegativity of between 0.5 and 1.7 units

Bond dipole

the unequal sharing of electrons

Spectrum of bonding

bonding ranging from ionic bonding through to pure covalent

Octet rule

the most stable arrangement for an atom is to have eight electrons in its outermost energy level with the electron configuration of a noble gas

Electron-deficient molecules

molecules that do not have a full valence shell

Lewis structure

represent the bonding in a molecule

Resonance structures

the different Lewis structures that can be drawn for the same molecule, or polyatomic ion

delocalized electrons

electrons that are shared between more than two nuclei in a molecule

VSEPR

the valence shell electron pair repulsion theory which enables us to predict the shape of the molecules

Electron domain

both bonding electrons and non-bonding electrons

Net dipole moment of a molecule

a measure of its overall polarity; the sum of all the bond dipoles in a molecule

Giant covalent structure

a network covalent structure; a macromolecular structure; a structure that does not form discrete molecules

Doping

the addition of small amounts of elements such as phosphorus or boron to pure pure silicon to improve electrical conductivity

Allotropes of carbon

diamond, graphite and the fullerenes

Allotropes

difference forms of the same element in the same physical state

Graphene

a single-layered material made up of individual sheets of graphite

intermolecular bonds

atoms covalently bonded within a molecule

intermolecular forces

forces that exist between molecules

temporary dipole

caused by changes in electron density within an atom or molecule

Induces dipole

a moeluce with a temporary dipole inducing a dipole in a neighboring molecule

Dipole - Dipole forces

attractions that only exist between polar molecules that have a permanent dipoles.

Hydrogen bonding

occurs between molecules that have an electronegative nitrogen, oxygen, or fluorine atom directly bonded to a hydrogen atom

Metallic bond

the bonding in metals through the electrostatic attraction between the lattice of positive metal ions and the "sea" of delocalized electrons; it is non-directional

Alloys

homogeneous mixtures composed of two or more metals or a metal and a non-metal; in its scientific usage, it is referring to a metallic element.

Sigma bond

formed by the direct head-on overlap of atomic orbitals

formal charge

used to determine which Lewis structure is the preferred one when there is more than one possibility.

Delocalized pi electrons

electrons that are shared between more than two nuclei; they are present in molecules and polyatomic ions for which there is more than one possible Lewis structure (resonance)

Electron domain geometry

total number of electron domains (bonding and non-bonding) around the central atom

Resonance energy

the difference in energy between the resonance hybrid structure and that of the most stable resonance structure

Ozone

composed of three oxygen atoms bonded together with a V-shaped, or bent, molecular geometry

Exothermic

something that released energy through heat

Hybridisation

the mixing or blending of atomic orbitals to form hybrid orbitals to be used for bonding

General properties of ionic solids

Generally highly soluble in water
Show good electrical conductivity only when molten or dissolved
Solids at room temperature
High melting and boiling points
Ionic compounds are brittle

List of diatomic molecules

fluorine, chlorine, bromine, and iodine

Bond type of ethane, ethene, ethyne

Ethane - single covalent, Ethene - double covalent, Ethyne - triple covalent

Difference in electronegativity and type of bonding

(>= 1.8 units) - ionic, (0.5 - 1.7 units) polar covalent, (0.1 - 0.4) - non-polar/weakly polar covalent, and (0) pure covalent