and O2− ions from the nonmetal oxygen, so (D) is the correct answer.
- B A polar molecule must contain polar covalent bonds. Of the
choices, only (A), (B), and (E) involve covalent bonding. However, (A) and
(E) involve diatomic molecules consisting of one element; we know that
these molecules will contain nonpolar covalent bonds, since their atoms
won’t differ in electronegativity. Carbon monoxide molecules contain
different nonmetals, and thus form polar covalent bonds. That’s why (B) is
correct.
- T, T, CE
Divide and conquer! Look at the first statement on its
own and decide whether it’s true or false. It’s true. Look
at the second statement by itself. It’s true. We know that
atoms have different electronegativities.
Let’s see if the whole sentence makes sense. “Some
covalent bonds are polar in nature because atoms of
different electronegativities are unequal in the degree to
which they attract electrons.” Does that make sense?
What makes a polar covalent bond polar? One of the
atoms in the bond hogs the shared electrons; one atom
has a higher electronegativity than the other. The
sentence makes sense, so fill in oval CE.
- F, F Divide and conquer. Look at the first statement by itself. Is it true?
No! We know that most atoms form bonds because they would like to
achieve a stable octet.
What about the second statement? It’s false. Ionic and
covalent bonding do provide atoms with a stable
configuration—the configuration that resembles a
stable octet.
- A A carbon atom has 4 valence electrons, and an oxygen atom has 6.
Using carbon as the central atom and arranging the atoms to give them
octets yields
Notice that the carbon dioxide molecule consists of 2
