Covalent Bonds: Hydrogen Sulfide

Hydrogen Sulfide undergoes covalent bonding – where two or more non-metal atoms are held together by one or more shared pairs of valence electrons. The atoms forming a covalent bond must have a relatively equal attraction for electrons (electronegativity). Hydrogen has an electronegativity of 2.2 and sulfur of 2.58. Covalent bonds tend to also have low melting and boiling points due to weak intermolecular forces which break down quite easily (BBC, 2014). Substances that are bonded covalently are also non-conductive, as they do not have any free electrons or an overall electric charge. In terms of solubility, covalent compounds are insoluble in polar solvents like water but dissolve in non-polar solvents like kerosene. They have a slow rate

Metals form positive ions and non-metals form negative ions, thus making ionic bonds the electrostatic forces of attraction between oppositely charged ions (BBC, 2014). Ionic bonds transfer valence electrons, from the metal to the non-metal. They tend to have high melting and boiling points since they are very strong and need a lot of energy for the bonds to be broken. Although ions are charged particles, ionic compounds can only conduct electricity if their ions are free to move. They do not conduct electricity when in a solid state, but only when dissolved in water or melted. Ionic compounds also tend to be solid at standard pressure and temperature. Also, because of the difference in electronegativity, they tend to have high polarity too.

The melting point of magnesium chloride is 714oC, and its boiling point is 1 412oC. These melting and boiling points are quite high – since ionic compounds use up a great amount of energy to break their bonds. Magnesium chloride is also soluble in polar solvents such as water, pyridine and ethanol, but insoluble in non-polar solvents like hexane. It is a strong electrolyte where it completely dissociates into its ions in aqueous solution. While solid magnesium chloride does not have the ability to conduct electricity; molten ionic salts (liquid) will conduct

These melting and boiling points are very high which is caused by strong attractive forces. Metallic bonding is the strong attraction between closely packed positive metal ions and a 'sea' of delocalized electrons. Iron as a pure element on the periodic table is also a good conductor, which relates back to the features of metallic bonding. Because the electrons involved in the bond of iron are free-moving, iron is a good conductor.

Network covalent bonds generally have very high melting points, and substance A can be classified as a covalent network crystal since it has a melting point of 3974oC. Covalent networks are insoluble in water – they cannot be broken apart by trying to dissolve them. As well as polar solvents, most covalent networks are also insoluble in non-polar solvents (unable to dissolve in all common solvents). Most covalent networks do not conduct electricity due to no their lack of mobile electrons, with some as