Covalent Bonding: Definitions, Structures, and Periodic Trends

What is covalent bonding?

Strong electrostatic forces of attraction between shared pair(s) of electrons and the nuclei of the bonded atoms.

What are small covalent molecules often referred to as?

Molecular structures.

How soluble are molecular molecules in water?

Generally poor

How good are molecular molecules as electrical conductors when solid

poor bc ions are fixed

How good are molecular molecules as electrical conductors when molten

poor bc no ions

molecular substances general state of matter

mainly gases and liquids

What are large covalent molecules known as?

Giant covalent molecules or macromolecules.

How soluble are macromolecules in water?

insoluble

How good are macromolecules as electrical conductors when solid

diamond and sand no bc electrons cant move

graphite good bc delocalised electrons between layers

How good are macromolecules as electrical conductors when molten

poor

macromolecular substances general state of matter

solids

Why do atoms share electrons in covalent bonding?

To achieve a full outer shell with a stable electron configuration, similar to that of a noble gas.

Give an example of a simple covalent molecule.

Methane (CH₄).

What is the octet rule?

The principle that atoms tend to bond in such a way that they have eight electrons in their outer shell.

Which elements often have less than 8 electrons in their outer shells?

Boron and aluminium, particularly in group 3 of the periodic table.

What is a notable exception to the octet rule?

Some stable molecules may have more or less than 8 electrons in their outer shell.

Which non-metals generally follow the octet rule?

Hydrogen, Fluorine, Neon, Helium, and Boron.

What is the significance of the periodic table in covalent bonding?

It helps predict bonding patterns and electron configurations of elements.

What is a common characteristic of non-metals in period 3 and below regarding their outer electrons?

They often have more than 8 electrons in their outer shells.

What is the role of shared electrons in covalent bonds?

They create a bond by being attracted to the nuclei of both bonded atoms.

What is the relationship between covalent bonding and molecular stability?

Covalent bonding leads to the formation of stable molecules.

What is the difference between molecular structures and giant covalent structures?

Molecular structures consist of small numbers of atoms, while giant covalent structures consist of large networks of atoms.

What type of bond do carbon dioxide (CO₂) and water (H₂O) involve?

Covalent bonds.

What is a characteristic of covalent bonds compared to ionic bonds?

Covalent bonds involve the sharing of electrons, while ionic bonds involve the transfer of electrons.

What is the significance of achieving a full outer shell in covalent bonding?

It leads to increased stability of the molecule formed.

What is the typical electron configuration goal for atoms in covalent bonding?

To achieve an electron configuration similar to that of noble gases.

What is the effect of covalent bonding on the physical properties of substances?

It can affect melting points, boiling points, and solubility.