Draw the Lewis structure for each organic compound from its condensed structural formula. a. C2H4 b. CH3NH2 c. HCHO d. CH3CH2OH e. HCOOH

Chemical bonding is the force that holds atoms together in molecules. Atoms bond by either transferring or sharing electrons, usually to obtain a full outer shell, resulting in more stable configurations. There are three main types of chemical bonds: ionic, covalent, and metallic.

In organic compounds, like the ones given in the exercise (C2H4, CH3NH2, HCHO, CH3CH2OH, and HCOOH), covalent bonding is predominant. Covalent bonds form when two atoms share one or more pairs of electrons. This type of bond is characterized by the directionality, which means atoms are connected in specific orientations that dictate the molecule's geometry. For instance, C2H4 (ethene) has a double bond between the carbon atoms, resulting in a planar structure with 120-degree bond angles.

Valence electrons are the electrons located in an atom's outermost shell and are involved in bonding. Knowing the number of valence electrons an element has is crucial for predicting how it will bond with other atoms.

For example, carbon has four valence electrons and tends to form four bonds, as seen in CH3NH2 or CH3CH2OH. Hydrogen, with one valence electron, forms a single bond; nitrogen, with five, forms three bonds and has one lone pair; and oxygen, with six, typically forms two bonds and holds two lone pairs. Elements follow the octet rule, aiming for eight electrons in their valence shell, which is exemplified in the Lewis structures for each organic compound listed in the exercise.

Lewis dot symbols are a visual representation that shows the valence electrons as dots around the elements’ symbols. They provide a simple way to visualize and predict the bonding patterns of atoms and the arrangement of electrons.

When constructing Lewis structures, electrons are placed around an atom's symbol according to specific rules: pairing up only when necessary, and filling in orbitals according to their energy levels. For instance, in the molecule of formaldehyde (HCHO), the oxygen atom is represented with four dots around it, signifying its two lone pairs of electrons, while each hydrogen is represented with a single dot indicating its one electron available for bonding.

Molecular geometry refers to the 3-dimensional shape of a molecule. The geometric structure of molecules influences their reactivity, polarity, phase of matter, color, magnetism, and biological activity.

The VSEPR (Valence Shell Electron Pair Repulsion) theory is often used to predict molecular geometry by assuming that electron pairs around a central atom will spread out as far as possible to minimize repulsion. Taking CH3CH2OH (ethanol) as an example, the molecule's geometry is a result of tetrahedral arrangements around each carbon atom, with bond angles approximating 109.5 degrees. However, the presence of the hydroxyl group (OH) on one of the carbon atoms alters the local geometry at that atom, demonstrating how the specific attachments to atoms can affect the molecule's overall shape.