Book: Ch. 9

Question 1

Define: ionic bonding, covalent bonding, and metallic bonding

Answer 1

Ionic: metal-nonmetal action. Electron transfer observed between atoms with large differences in their tendencies to lose or gain electrons.
Covalent: nonmetals only. Two atoms differ little, or not at all, in their tendencies to lose or gain electrons, so they share electrons.
Metallic: metals only. They sort of have this sea of their valence electrons pooled between them.

Question 2

Define: Lewis electron-dot symbol

Answer 2

Element symbol represents the nucleus and inner electrons, and dots around the symbol represent the valence electrons.

Question 3

Define: lattice energy (delta H°_lattice)

Answer 3

The enthalpy change accompanying 1 mol of ionic solid separating into gaseous ions.

Question 4

Define: Born-Haber cycle

Answer 4

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

Question 5

A covalent bond arises from _____.

Answer 5

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

Question 6

Define: shared pair (or bonding pair)

Answer 6

In Lewis symbols, this is the name for pairs of dots (electrons) shared between two atoms. It is either drawn as a dash between the two atoms or two dots separating the atoms.

Question 7

Define: lone pair (or unshared pair)

Answer 7

In Lewis symbols, a pair of electrons not involved in bonding.

Question 8

Define: bond order

Answer 8

Number of electron pairs being shared by a given pair of atoms.

Question 9

Define: bond energy (BE, bond enthalpy, bond strength)

Answer 9

The strength of a covalent bond, which depends on the magnitude of the attraction between the nuclei and shared electrons. Bond energy says how much energy is needed to overcome this attraction and is defined as the standard enthalpy change for breaking the bond in 1 mol of gaseous molecules.

Question 10

Define: bond length

Answer 10

The distance between the nuclei of the two bonded atoms.

Question 11

Define: electronegativity (EN)

Answer 11

The relative ability of a bonded atom to attract shared electrons.

Question 12

Define: polar covalent bond

Answer 12

Occurs when atoms with very different ENs, leading to the bonding pair being shared unequally between the atoms.

Question 13

Define: nonpolar covalent bond

Answer 13

A covalent bond in which the bonding pair is shared equally.

Question 14

Define: electronegativity difference (∆EN)

Answer 14

The difference between the ENs of bonded atoms, which directly measures the polarity of the bond.

Question 15

Define: partial ionic character

Answer 15

A parameter closely related to ∆EN: the two are correlated positively.

Question 16

Define: electron-sea model

Answer 16

A model for metallic bonds that says all the metal atoms in the sample contribute their valence electrons to form a delocalized electron “sea” throughout the piece.