CHAPTER 6: CHEMICAL BONDING

What poverty of the two atoms un a covalent bond determines whether or not the bond will be polar?

electronegativity

what two factors determine whether or not a molecule is polar?

electronegativity difference and molecular geometry or unshared electron pairs

The notation for sodium chloride, NaCl, stands for

formula unit

Atoms with a strong attraction for electrons they share with another atom exhibit

high electronegativity

A chemical bond that results from the electrostatic attraction between positive and negative ions is called a(n)

ionic bond

If a bond's character is more than 50% ionic, then the bond is called a(n)

ionic bond

The greater the electronegativity difference between two atoms bonded together, the greater the bond's percentage of

ionic character

the lattice energy of compound A is greater in magnitude than that of compound B. what can be concluded from this fact

it will be more difficult to break the bonds in compounds A than those in compound B

compared with the neutral atoms involved in the formation of an ionic compound the crystal lattice that results is

lower in potential

In a crystal of an ionic compound, each cation is surrounded by a number of

negative ions

A covalent bond in which there is an unequal attraction for the shared electron is

polar

Bonds that possess between 5% and 50% ionic character are considered to be

polar covalent

If electrons involved in bonding spend most of the time closer to one atom rather than the other, the bond is

polar covalent

How can electronegativity be used to distinguish between an ionic bond and covalent bond?

the difference between the electronegativity of the two atoms in a bond will determine whether the bond is ionic or covalent. If the difference in electronegativity is greater than 1.7, the bond is considered ionic

how are dipol-dipole attractions, london dispersion, and hydrogen bonding?

they are all forces of attraction between molecules. in all cases there is an attraction between the slightly negatively-charged portion of one molecule and the slightly positively charged portion of another molecule

Describe the electron distribution in a polar-covalent bond and its effect on the partial charges of the compound.

the electron density is greater around the more electronegative atom, giving that part of the compound a partial negative charge. the other part of the compound has an equal partial positive charge.

in water two hydrogen atoms are bonded to one oxygen atom. why isn't water a linear molecule?

the electron pairs that are not involved in bonding also take up space, creating a tetrahedron of electron pairs and making the water molecule angular or bent

describe the force that holds two ions together in an ionic bond

the force of attraction between unlike charges hold a negative ion and a positive ion together in an ionic bond

If two covalently bonded atoms are identical, the bond is identified as

nonpolar covalent

A chemical bond between atoms results from the attraction between the valence electrons and __________ of different

nuclei

identify the major assumption of the VSEPR theory which is used to predict the shape of atoms

pairs of valence electrons repel one another

what orbitals combine together to form sp3 hybrid orbitals around a carbon atom?

the s orbital and all three p orbitals from the second energy level

The electrons involved in the formation of a chemical bond are called

valence electrons

the forces of attraction between molecules in a molecular compound are generally

weaker than than the attractive forces among formula units in ionic bonding

Write the formula for an example of each of the following compounds: A. nonpolar covalent compound B. polar covalent compound C. ionic compound

A. H2 B. HCl C. NaCl

Describe how a covalent bond holds two atoms together

a pair of electrons is attracted to both nuclei of the two atoms bonded together

A covalent bond consists of _____________

a shared electron pair

A bond's character is more than 50% ionic if the electronegativity difference between the two atom is greater than

1.7

how is hydrogen bond different from an ionic or covalent bond?

a hydrogen bond is a dipole-dipole attraction between a partially positive hydrogen atom and the unshared electron pair of a strongly electronegative atom such as O, N, or F. unlike ionic or covalent bonds, in which electrons are given up or shared, the hydrogen bond is a weaker attraction. Hydrogen bond are generally intermolecular, while ionic and covalent bonds occur between ions or respectively.

H2S and H2O have similar structures and central atoms belong to the same group. yet H2S is a gas at room temperature and H2O is a liquid. use bonding principles to explain why this is

Oxygen has higher electronegativity than sulfur, which creates a highly polar bond. increased polarity in H2O bonds means stronger intermolecular attraction, making water a liquid at room temperature. hydrogen bonding exists between water molecules, but not between hydrogen sulfide molecules.