Chemistry - properties of solids

Metalic substances - electrical conductivity

The structure of metalic substances is a 3-D network of metal cations surrounded by delocalised electrons. The cations are held together by strong metallic bonds between the metal cations and all the delocalised electrons. They are good conductors of electricity as the delocalised electrons are able to move through the substance, transporting a current. 

Metalic substances - Thermal Conductivity

They are all good conductors of heat as the delocalised electrons are able to move through the substance, transferring heat to the cations. The atoms are also very densely packed which allows the atoms to easily transfer vibrations to neighbouring atoms which makes them more thermally conductive.

Metalic substances - insolubility

Metals are not soluble in water, as the metallic bonds are too strong to be broken by the attraction to the water molecules. This insolubility is because the forces of attraction between the metal atoms are stronger than those between the metal atoms and water molecules.

Metalic substances - melting point

As the metallic bonds in metals are strong, a lot of energy is required to overcome bond between the metal cations and delocalized valence electrons. Therefore, metals have high melting points.

Metalic substances - malleability and ductility

In metals, atoms are arranged in a regular lattice and are held together by metallic bonds. These bonds consist of a "sea" of free-moving electrons that surround positively charged metal ions and create a non-directional bond. Since the bond is non-directional, metal ions are able to slide past each other without breaking the bonds. This enables metals to be hammered into thin sheets (malleability) and drawn into wires (ductility).

metalic substances - bond

A metallic bond is a type of chemical bond found in metals. It's formed by the attraction between the free-moving electrons and the positively charged metal ions.

what are metalic substances made up of

atoms

Ionic substances - electrical conductivity

Solid ionic substances are a 3D lattice of ions held together by strong ionic bonds. These forces hold the ions in a fixed position. As the ions cannot move, the solid will not conduct electricity. When melted (or dissolved in water) the charged ions become free to move, and this allows the liquid to conduct electricity

ionic substances - thermal conductivity

Solid ionic substances do not conduct heat well due to the rigid structure of the ionic lattice, which limits the movement of particles. However, when liquid or dissolved in water, the particles are free to move and therefore better conduct heat.

ionic substances - solubility

Ionic substances dissolve in water because the attraction between the ions and water molecules is strong enough to overcome the ionic bonds between the ions. The ions become separated from the 3-D lattice and are free to move around in solution. 

ionic substances - melting point

Ionic solids are made of positive ions and negative ions, held together by strong electrostatic attractions in a 3– D lattice structure. As these electrostatic attractions (ionic bonds) are strong, they require a large amount of energy to overcome them, so their melting and boiling points are high.

ionic substances - brittleness

The bonds within ionic solids are directional so they are not malleable or ductile. Instead they are brittle. If oppositely charged ions are forced to shift position then like charges are lined up and repel, causing the crystal to shatter

ionic substances - bond

Ionic substances consist of positively and negatively charged ions held together by strong ionic bonds, resulting in a stable lattice structure.

what are ionic substances made up of

ionic compounds from a crystal lattice structure where each ion is surrounded by ions of the opposite charge.

covalent networks - electrical conductivity

Covalent networks typically do not conduct electricity because they lack free-moving charged particles. However, some covalent network compounds, like graphite, can conduct electricity due to the presence of delocalized electrons.

covalent networks thermal conductivity

• Diamond: In diamond, each carbon atom forms strong covalent bonds with four other carbon atoms in a tetrahedral arrangement. These bonds are incredibly strong and rigid, allowing efficient transmission of vibrational energy throughout the lattice.

• Graphite: Conducts heat well along its layers due to delocalized electrons. However, its thermal conductivity is much lower perpendicular to the layers.

covalent networks - solubility

Covalent networks are insoluble because they have extremely strong covalent bonds that form a continuous structure throughout the entire material. Breaking these bonds requires a lot of energy, unlike weak intermolecular forces that can be easily disrupted by solvents.

covalent networks - melting point

In order to melt covalent network substances strong covalent bonds between atoms must be broken. Because of their strength, a lot of energy is required to break these bonds and separate atoms. Therefore diamond, graphite and SiO2 all have high melting points

covalent networks - maleability

diamond is not malleable due to its rigid crystal structure formed by strong covalent bonds. When force is applied, it tends to shatter rather than deform.

While the layers that make up graphite can easily slide past each other, making graphite useful as a lubricant and in pencils, the material itself is brittle and can break easily when subjected to force.

covalent networks - bond

Covalent Bonds: These are strong bonds formed when atoms share electrons. In covalent networks, each atom is bonded to multiple other atoms, creating a large, stable structure.

what are covalent networks made of

Diamond: Diamond is made of carbon atoms. Each carbon atom is covalently bonded to 4 other C atoms in a tetrahedral arrangement, which forms a covalent network solid.

Graphite: Graphite consists of C atoms each covalently bonded to 3 other C atoms in a 2D arrangement, forming layers with weak intermolecular forces between them. The weak forces of attraction between the layers of atoms in graphite are easily broken. Therefore, graphite is soft and slippery and the layers can slide over each other. This makes it useful as a lubricant.

molecular substances - electrical conductivity

Molecular solids are made of molecules in which the atoms are covalently bonded to each other. They do not contain free moving charged particles (no delocalised electrons or mobile ions). Therefore molecular substances cannot conduct in the solid or liquid state

molecular substances - thermal conductivity

Unlike metals, molecular solids do not have free-moving electrons that can carry thermal energy. Larger molecules can store vibrational energy internally, reducing the transfer to neighbouring molecules. Molecular solids also have a lower density which means there are fewer molecules in a given volume making it harder to transfer energy effectively through vibrations.

molecular substances - solubility

Non-polar molecules are usually soluble in non-polar solvents such as cyclohexane. Since both molecules have similar weak intermolecular forces between them, then weak forces can also exist between the two different molecules. (Like dissolves like).

Polar molecules are usually soluble in polar solvents such as water. Since both types of molecules have similar weak intermolecular forces between them, then weak forces can also exist between the two different molecules. (Like dissolves like).

molecular substances - melting point

Molecular solids are made of molecules. There are weak intermolecular forces or van der Waals forces (forces BETWEEN molecules) holding the molecules together, and they require a small amount of energy to be overcome. This means the substances have low melting and boiling points.

molecular substances - brittleness

Since the weak intermolecular forces allow the molecules to be easily separated this makes them either soft or brittle - easy to break the solid

molecular substances - bond

There are strong covalent bonds between the atoms in the molecules (intramolecular forces) but it is NOT these that are being broken when the solids melts or the liquid boils

what are molecular substances made of

molecules which can be polar (have a charged and non charged side) or non-polar (have evenly distributed charges)