Final answer:
The type of compound - ionic, covalent, or metallic - can be determined by considering the elements' positions on the periodic table, with metals and non-metals typically forming ionic compounds, non-metals forming covalent compounds, and metals forming metallic bonds.
Step-by-step explanation:
To determine the compound type for a given formula, one must consider the elements involved and their positions in the periodic table. Compounds can be broadly categorized as ionic, covalent, or metallic.
Ionic compounds typically form between metals and non-metals, where electrons are transferred from one atom to another. The metal loses electrons to become a positive ion (cation), and the non-metal gains electrons to become a negative ion (anion). An example is NaCl, where Na is a cation (Na+) and Cl is an anion (Cl-).
Covalent compounds form when non-metals bond together by sharing electrons. Two or more non-metals will create a molecule with this type of bond. For instance, CO2 is a covalent compound consisting of one carbon atom double bonded to two oxygen atoms.
Metallic compounds involve the pooling of electrons among metal atoms, creating a 'sea of electrons' that provides the basis for metallic bonding. This type of bonding gives metals their characteristic properties such as conductivity and malleability. Aluminum (Al), for example, is a metallic substance.
To predict the type of compound formed from elements based on their location within the periodic table and determine formulas for simple ionic compounds, one should look at the groups (columns) of the periodic table. Metals are found to the left and centre (and hydrogen), whereas non-metals are typically to the right (excluding hydrogen). Metalloids bridge these two sections and have properties of both metals and non-metals.