Chemical Bonding

State the type of bonding present in magnesium and in sodium chloride.

bonding in magnesium

bonding in sodium chloride

Explain the difference in the melting points of magnesium and sodium chloride.

Explain the difference in the melting points of phosphorus and sulfur in terms of structure and bonding.

Define electronegativity.

Explain why electronegativity increases across a period.

Name the strongest intermolecular force that exists between $\text{NH}_3(\text{l})$ molecules.

Draw a diagram to show the formation of the strongest intermolecular force between two molecules of $\text{NH}_3(\text{l})$.

Include any relevant lone pairs of electrons and dipoles.

The melting points of ice and ammonia are shown in Table 1.2.

Table 1.2

Suggest two reasons for the difference in the melting points of ice and ammonia.

Predict the shapes of AlCl₃ and PCl₃.

Draw diagrams to show the shapes, name the shapes and state the bond angles.

Explain, in terms of structure and bonding, why the melting point of SiCl₄ is much lower than that of NaCl.

Explain why the melting point of SiCl₄ is higher than that of PCl₃.

Draw the 'dot-and-cross' diagram of a molecule of SiCl₄.
Show outer electrons only.

Complete the table below by using simple hydrogen-containing compounds. One example has been included.

Draw a ‘dot-and-cross’ diagram of the $\text{TeF}_6$ molecule, showing outer electrons only.

What will be the shape of the $\text{TeF}_6$ molecule?

What is the $\text{F}-\text{Te}-\text{F}$ bond angle in $\text{TeF}_6$?

Complete the table below by using simple hydrogen-containing compounds. One example has been included.

Draw a ‘dot-and-cross’ diagram of the TeF₆ molecule, showing outer electrons only.

What will be the shape of the TeF₆ molecule?

What is the F–Te–F bond angle in TeF₆?

In the boxes below, draw the ‘dot-and-cross’ diagram of a molecule of each of these compounds. Show outer electrons only.
State the shape of each molecule.

Explain, using ammonia as the example, the meaning of the term bond polarity.

Explain why the ammonia molecule is polar.

State one physical property of ammonia which is caused by its polarity.

When ammonia gas is mixed with hydrogen chloride, white, solid ammonium chloride is formed.

State each type of bond that is present in one formula unit of ammonium chloride and how many of each type are present.
You may draw diagrams.

Chlorine, $\text{Cl}_2$, is a gas at room temperature whereas bromine, $\text{Br}_2$, is a liquid under the same conditions.

Explain these observations.

The gases nitrogen, $\text{N}_2$, and carbon monoxide, $\text{CO}$, are isoelectronic, that is they have the same number of electrons in their molecules.

Suggest why $\text{N}_2$ has a lower boiling point than $\text{CO}$.

a co-ordinate bond

a covalent bond

a lone pair

Hydrogen cyanide, $\text{HCN}$, is a gas which is also isoelectronic with $\text{N}_2$ and with $\text{CO}$.
Each molecule contains a strong triple bond with the following bond energies.

Although each compound contains the same number of electrons and a strong triple bond in its molecule, $\text{CO}$ and $\text{HCN}$ are both very reactive whereas $\text{N}_2$ is not.

Suggest a reason for this.

the element in Period 3 (Na to Ar) with the greatest electrical conductivity

.............

From the section of the Periodic Table above, identify two elements whose hydrides form hydrogen bonds between their molecules.

............. and .............

What is the $\text{H}-\text{C}-\text{H}$ bond angle at the terminal $\text{=CH}_2$ group in propene?

When cyclopropane reacts with chlorine, three different compounds with the molecular formula $\text{C}_3\text{H}_4\text{Cl}_2$ can be formed.

Draw displayed structures of each of these three compounds.

What is the H–C–H bond angle at the terminal =CH₂ group in propene?

When cyclopropane reacts with chlorine, three different compounds with the molecular formula C₃H₄Cl₂ can be formed.

Draw displayed structures of each of these three compounds.