DE_Chem_Unit3_Benchmark_Master

One of the different periodic properties that affects the behavior and interactions of elements is electronegativity. In particular, this property plays an important role in determining the nature of chemical bonds that are formed, such as covalent bonds and ionic bonds.

Look at the table below and calculate the electronegativity difference between magnesium and oxygen. Use this information to determine the type of bond they form and how the electron cloud is distributed in the resulting molecule. Which type of compounds could they form, separately, with the other elements?

A simple and visual way to better understand the electron configuration and behavior of elements and molecules is to look at their Lewis (electron) dot structures. The Lewis structure of an atom, such as oxygen or magnesium, consists of its atomic symbol surrounded by dots.

The number of dots represents the number of valence electrons or outer shell electrons associated with the atom. By utilizing Lewis structures, we can determine how many electrons are available to form chemical bonds and apply the octet rule.

Because the reaction between magnesium and oxygen releases so much energy in the form of light and heat, scientists must use precautions to avoid looking directly at the intense flame generated as this chemical reaction occurs. This spectacular reaction is clear evidence of the energy released in this exothermic reaction. However, despite its nature, why do you think this reaction needs initial ignition to occur?

In the reaction between magnesium and oxygen, the hydrocarbon propane (C₃H₈) was used to provide the activation energy by ignition. Methane has similar chemical properties to propane. It is also used for similar purposes, such as a fuel source to power vehicles.

Methane burns readily in oxygen, producing carbon dioxide and water. Consider the table shown earlier about the electronegativity of all elements, and use this information to imagine how the electronegative difference among carbon and hydrogen affects the chemical and bulk properties of methane.

Methane is quite a simple molecule. However, thousands of more complex molecules are also found in nature. Some of them are known as polymers. These relatively huge and long molecules originate from simpler ones through polymerization reactions in which the simpler units join together to make long chains.

For example, starch is a polymer made by joining simple sugars together to form one giant molecule. In past centuries, humans have learned how to produce numerous types of artificial polymers for a variety of different uses. Many of these polymers make materials we call plastics. A famous example is represented by nylon.

Nylon is a plastic fiber invented in 1935 as the first successful synthetic fabric. Its versatility in use is mainly due to its molecular structure and chemical properties. Since the beginning, nylon has been used for a wide range of applications, including parachutes and monofilament fishing line. Nylon also paved the road for the use of other synthetic fabrics such as polyester, which is commonly found in clothing.