College Chemistry Ch3

Structure and Properties of Ionic and Covalent Compounds

Chemical bond

the force of attraction between any two atoms in a compound

Lewis Symbol

a way to represent atoms using the element symbol and valence electrons as dots

Ionic Bond

attractive force due to the transfer of one or more electrons from one atom to another

Covalent bond

attractive force due to the sharing of electrons between atoms

Metals tend to form____ because they have low Ionization energy and low electron affinity

Cations

Non-metals tend to form ____ because they have a high ionization energy and a high electron affinity

Anions

Ions are formed by

the transfer of electrons

Reactions between metals and nonmetals tend to form ____

Ionic Compounds

In crystals, ions are arranged in a ____

Crystal Lattice

Polar covalent bonding

bonds made up of unequally shared electron pairs

Electronegativity

a measure of the ability of an atom to attract electrons in a chemical bond

The most Electronegative elements can be found here

Upper right corner of the periodic table

The least electronegative elements can be found here

Lower left corner of the periodic table

Nomenclature

the assignment of a correct and unambiguous name to each and every chemical compound

Two naming systems for compounds

Ionic and Covalent Compounds

Formula

the representation of the fundamental compound using chemical symbols and numerical subscripts

A positive ion retains the name of the element; change the anion suffix to

-ide

Monatomic ions

ions consisting of a single charged atom

Polyatomic ions

ions composed of 2 or more atoms bonded together with an overall positive or negative charge

Molecules

compounds characterized by covalent bonding

Melting point

the temperature at which a solid is converted to a liquid

Boiling point

the temperature at which a liquid is converted to a gas

dissociate

often dissolve in water, where they ____- form positive and negative ions in a solution

Electrolytes

ions present in solution, allowing the solution to conduct electricity

non electrolytes

covalent solids, usually do not dissociate and do not conduct electricity

Single bond

one pair of electrons are shared between two atoms

Double bond

two pairs of electrons are shared between two atoms

Triple bond

three pairs of electrons are shared between two atoms; very stable

Bond energy

the amount of energy required to break a bond holding two atoms together

triple bond>double bond>single bond

Bond length

the distance separating the nuclei of two adjacent atoms

single bond>double bond>triple bond

Resonance

two or more Lewis structures that contribute to the real structure

Incomplete Octet

less than eight electrons around an atom other than H

ex: BeH2 : H-Be-H

Odd electron

if there is an odd number of valence electrons, it is not possible to give every atom eight electrons

ex: N=O

Expanded Octet

an element in the 3rd period or below may have 10 and 12 electrons around it (most common exception)

VSEPR theory

Valence Shell Electron Pair Repulsion theory

used to predict the shape of the molecules

Trigonal Planar Structure

3 bonded atoms around central atom

bond angles of 120 degrees

Tetrahedron

primary structure of the full octet

each bond angle is 109.5 degrees

4 bonded atoms around the central atom

Trigonal Pyramidal

3 bonded atoms and one lone pair (4 groups)

107 degree bond angles

bent/ angular

2 bonded atoms and two lone pair (4 groups)

104.5 degree bond angles

Linear

2 bonded atoms with no lone pairs

Polar molecules

will align themselves in an electric field

Nonpolar molecules

will not align themselves in an electric field

Polar or Nonpolar?: Molecules that have no lone pair on the central atom; all terminal atoms are the same

Nonpolar

Polar or Nonpolar?: Molecules with one lone pair on the central atom

Polar

Polar or Nonpolar?: Molecules with more than one lone pair on the central atom

usually polar

Intramolecular forces

Attractive forces WITHIN molecules

Intermolecular forces

Attractive forces BETWEEN molecules; determine many physical properties

Solubility

The maximum amount of solute that dissolves in a given amount of solvent at a specific temperature