Draw a dot diagram for acetone, \(\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}\), the active ingredient in nail polish remover. The oxygen is bound to only one carbon, and that carbon has no hydrogens bound to it.

Valence electrons are the outermost electrons of an atom and are crucial in determining how the atom interacts with other atoms. In essence, they are the electrons involved in forming chemical bonds. For example, in the provided exercise, when constructing the Lewis Dot Structure for acetone, the very first step is to count the number of valence electrons for each atom involved. Carbon atoms have four valence electrons, hydrogen has one, and oxygen six. Knowing this, students can add them up to find the total number of valence electrons that are available for bonding in the acetone molecule.

It's important to remember that knowing the number of valence electrons an element has can often be deduced from its group number on the periodic table. The group number for main-group elements generally corresponds to the number of valence electrons. Therefore, by simply looking at the periodic table, you can gather that elements in group 1 have one valence electron, elements in group 14 have four, and so on. This concept is fundamental when beginning to draw the Lewis Dot Structure of any molecule.

Molecular structure refers to the three-dimensional arrangement of atoms within a molecule and the chemical bonds that hold these atoms together. When creating a Lewis Dot Structure, as shown in our exercise for acetone (\( \text{C}_3\text{H}_6\text{O} \)), we follow certain steps to ensure the correct molecular structure is achieved. After counting the valence electrons, the next step is figuring out how these atoms will connect -- this is often called the 'Skeletal Structure'.

For the acetone molecule, a specific carbon atom is bonded to the oxygen and contains no hydrogen atoms. The other carbons are bonded to hydrogen atoms. This information guides us in arranging the atoms in a certain pattern before considering electron pairs. The skeletal structure does not show the bonds as lines yet, but places atoms next to each other in the correct connectivity order. It's like a blueprint that lets us visualize the molecule's shape and prepares us for the next steps, like distributing the electrons effectively to achieve a stable structure under the octet rule.

The Octet Rule is a chemical rule of thumb that reflects a pattern of atoms sharing or transferring electrons to result in a full valence shell, typically totaling eight electrons for most atoms. Hydrogen, however, is an exception because it is stable with two electrons. Applied to the Lewis structure for acetone, the octet rule determines where the remaining valence electrons will be placed after the bonds are formed.

In our exercise, after ensuring all the carbon and hydrogen atoms are connected correctly, oxygen must form a double bond with the unique carbon atom to satisfy the octet rule, resulting in the final structure. The double bond counts as four of the oxygen's valence electrons, and it retains two lone pairs to complete its octet. This structure displays all of the oxygen and carbon atoms fulfilling the octet rule, which is vital for the molecule's stability. The rule serves as an important predictor for the type of bonds that atoms will form, helping students predict the chemical behavior and properties of the molecules they are studying.