what shape would you expect a molecule to hove that was based on an atom with only two bonding pairs of electrons? Three bonding pairs? Four?

To determine the shape of a molecule, you need to consider its electron geometry and its molecular geometry. The VSEPR theory (Valence Shell Electron Pair Repulsion theory) can help us understand the shapes of molecules based on the number of bonding pairs and lone pairs of electrons around the central atom.

1. Two bonding pairs of electrons:
If a molecule has only two bonding pairs of electrons, it falls into the electron geometry category known as "linear." This means that the atoms connected to the central atom will form a straight line. For example, in a molecule like carbon dioxide (CO2), the carbon atom is surrounded by two oxygen atoms, creating a linear molecular shape.

2. Three bonding pairs of electrons:
In the case of three bonding pairs of electrons, we have a few possibilities depending on whether there are any lone pairs present. If there are no lone pairs, the molecular geometry will be trigonal planar. For example, molecules like boron trifluoride (BF3) have three bonding pairs, resulting in a flat or planar shape.

If there is one lone pair present, the molecular geometry will be bent, also known as V-shaped. A common example is water (H2O), where the oxygen atom has two bonding pairs and two lone pairs. This arrangement causes a bent shape due to the repulsion between the bonding and lone pairs.

3. Four bonding pairs of electrons:
When a molecule has four bonding pairs of electrons, there are a few possible arrangements. If there are no lone pairs, the molecule will have a tetrahedral electron geometry and molecular geometry. An example is methane (CH4), where carbon is bonded to four hydrogen atoms, resulting in a three-dimensional tetrahedral shape.

If there is one lone pair, the molecular geometry will be trigonal pyramidal. For instance, ammonia (NH3) has three hydrogen atoms bonded to the central nitrogen atom, along with one lone pair. This arrangement produces a pyramid-like shape.

If there are two lone pairs, the molecular geometry will be bent or V-shaped. For example, water (H2O) also falls into this category due to its two lone pairs and two bonding pairs.

In summary, the shape of a molecule depends on the number of bonding pairs and lone pairs of electrons around the central atom, which can be determined using the VSEPR theory.