Cap 9

ionic bonding

bonding between atoms with large differences in their tendencies to lose or gain electrons

covalent bonding

bonding which occurs most commonly between nonmetals; each nonmetal atom holds on to its own electrons tightly and attracts other electrons as well

metallic bonding

type of bonding in which the electrons are delocalized, moving freely throughout the entire piece of metal

electron pooling

the enormous number of atoms in a sample of a metal pool their valence electrons in a sea of electrons that flows between and around each metal ion core thereby attracting and holding them together

lewis electron dot symbol

a method for depicting the valence electrons of interacting atoms that predict how they bond

octet rule

when atoms bond, they lose gain or share electrons to attain a filled- outer level of eight electrons

ionic bonding model

a model in which the central idea is the transfer of electrons from metal atoms to nonmetal atoms to form ions that attract each other and form a solid compound

lattice energy

the enthalpy change that accompanies the process of 1 mol of ionic solid separating into gaseous ions

• a measure of the strength of the ionic interactions.

• influences macroscopic properties

born haber cycle

a series of steps from elements to ionic solid for which all the enthalpies are known except the lattice energy

coulombs law

states that the electrostatic energy between two particles is directly proportional to the product of their charges and inversely proportional to the distance between them

ion pairs

gaseous ionic molecules rather than individual ions

covalent bond

arises from the balance between the nuclei attracting the electrons and electrons and nuclei repelling each other

bonding pair

is represented by a pair of dots or a line

lone pair

an outer level electron pair that is not involved in bonding

bond order

the number of electron pairs being shared by a given pair of atoms

single bond

the most common bond and consists of one bonding pair of electrons; has a bond order of 1

double bond

consists of two bonding electron pairs, four electrons shared between two atoms. has a bond order of 2

triple bond

consists of three shared pairs: two atoms share six electrons. has a bond order of 3

bond energy

the energy needed to overcome the attraction between the nuclei and shared electrons.

• the standard enthalpy change for breaking the bond in 1 mol of gaseous molecules

bond length

the distance between the nuclei of the two bonded atoms

covalent bonding model

proposes that electron sharing between pairs of atoms leads to strong localized bonds

infrared spectroscopy

an instrumental technique used to study covalently bonded molecules

• the source emits radiation of many wavelengths but only those in the IR region are selected

fuel

a material that reacts with O2 to release energy

electronegativity

the relative ability of a bonded atom to attract shared electrons

polar covalent bond

unequal distribution of electron density

nonpolar covalent bond

atoms are identical, the bonding pair is is chared equally

electronegativity difference

the difference between the electronegativity values or the bonded atoms

partial ionic character

a greater electronegativity difference results in larger partial charges and higher partial ionic character

electron sea model

proposes that all the metal atoms in the sample contribute their valence electrons to form a delocalized electron sea throughout the piece with the metal ions lying in an orderly array

alloy

two or more metals for a solid mixture of variable composition