Structure And Bonding

Question 1

Covalent bonding

Answer 1

covalent bonding, occurs with elements like carbon in the middle
of the periodic table, which would otherwise have to gain or lose several electrons to form an ion
with a complete valence shell. A covalent bond is a two-electron bond, and a compound with
covalent bonds is called a molecule. Covalent bonds also form between two elements from the
same side of the table, such as two hydrogen atoms or two chlorine atoms. H, Cl, and CH, are
all examples of covalent molecules.

Question 2

Ethanol and dimethyl! ether are

Answer 2

are constitutional isomers because they have the same molecular
formula, but the connectivity of their atoms is different. For example, ethanol has one
C—C bond
and one O-H bond, whereas dimethyl ether has two C—O bonds. A second class of isomers,
called stereoisomers, is introduced in Section

Question 3

Exceptions to the octet rule

Answer 3

Elements in groups 2A and 3A of the periodic table, such as beryllium and boron, do not have
enough valence electrons to form an octet in a neutral molecule. Lewis structures for BeH, and
BF; show that these atoms have only four and six electrons, respectively, around the central atom.
There is nothing we can do about this! There simply aren’t enough electrons to form an octet.