types of bonding#

Intermolecular forces (IMFs) are attractive forces that exist between molecules. Don't confuse them with intramolecular forces (like covalent or ionic bonds), which are the forces within a single molecule or compound, holding atoms together. IMFs are significantly weaker, but they control many physical properties like melting points, boiling points, and solubility.

There are three main types of IMFs, listed from weakest to strongest:

• Protons: Positively charged, located in the nucleus. The number of protons defines the element (atomic number, Z).
• Neutrons: Neutrally charged, located in the nucleus. They add mass but don't affect the element's identity.
• Electrons: Negatively charged, orbiting the nucleus in specific energy levels called shells. They dictate an atom's chemical behavior.

Ionic bonds form because atoms want to achieve a stable electron configuration, usually a full outer shell, like noble gases. This often means having eight electrons in their outermost shell (the octet rule). For many atoms, it's easier to gain or lose a few electrons than to share many.

When an atom loses electrons, it becomes positively charged. This positively charged atom is called a cation. Metals typically form cations.
When an atom gains electrons, it becomes negatively charged. This negatively charged atom is called an anion. Non-metals typically form anions.

When atoms form covalent bonds, they share electrons rather than transferring them. This sharing allows each atom to achieve a stable electron configuration, often resembling that of a noble gas (typically eight valence electrons, known as the octet rule). The number of shared electron pairs determines if it's a single, double, or triple bond.

Before you can determine molecular geometry, you need to draw a Lewis structure. This is a diagram that shows the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule.

This shared pool of electrons is often called a delocalized electron sea or electron cloud. Within this sea, the metal atoms become positively charged ions (because they've lost their valence electrons), and these positive ions are attracted to the negatively charged electron sea. This strong, non-directional attraction is what we call metallic bonding.

Here's why this model is so powerful for explaining metal properties: