Chapter 20

Explain why carbon atoms form four covalent bonds?

A carbon atom has 4 electrons in its outer shell, and requires 8 to make itself stable. As all elements want to be stable, they need to find electrons from elsewhere.

Describe the first process used in the refining of petroleum.

A powdered catalyst

How did the three major fossil fuels form.

Algae from under water a million years ago

Explain why you would expect two structural isomers to have diffrent boling points?

Because of the diffrent bonding

The molecule of both cyclohexane and benzene have six carbon atoms bonded in a ring. What is the diffrence between these two compounds?

Benzene is an aromatic ring (alternating single and double bonds) while cyclohexane is all single bonds.

Describe the bonding between carbon atoms in benzene.

Both are shared

What are the two varibles used to classify coal?

Carbon and Sulfur

Describe the chemical composition of coal.

Coal is mostly carbon, but it has some other elements in it, notably sulfur, hydrogen, oxygen and nitrogen.

Explain why cacking is a necessary step in petroleum refining.

Cracking processes break down heavier hydrocarbon molecules (high boiling point oils) into lighter products such as petrol and diesel. These processes include catalytic cracking, thermal cracking and hydrocracking.

Describe the bonding between atoms in an alkene?

Double bonding

What are two ways that carbon atoms can be arranged in an alkane?

Double bonds and triple bonds

Name two types of stereoisomers?

Geometrical and optical

Describe the hydrocarbons found in natural gas.

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon

What structural must be present in a molecule for geometric isomers to exist?

Molecular structure

What is a cycle hydrocarbon?

Organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls

What is the diffrence between satuarated and unsatuarated hydrocarbons?

Saturated carbons are single bonded and have a greater compliment of hydrogen. Unsaturated carbons are generally doubled bonded and thus are attached to fewer hydrogen

What is the relationship between two molecules that are optical isomers?

The both have the same valence

Describe the polarity of alkane molecules?

The greater the electronegativity difference between atoms in a bond, the more polar the bond. Partial negative charges are found on the most electronegative atoms, the others are partially positive.

How can an asymmetric carbon be identified?

The middle carbon has 4 bonds so it is bonding to 4 other groups

What types of bonds are present in an alkyne?

Triple bonds