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The periodic table

The periodic table displays all known chemical elements and provides each element with a group and period number. The period number indicates the number of electron shells, while the group number shows the number of outer electrons (valency). An element's location in the table block defines its valence electrons' orbitals. By using the period and group number as coordinates, we can locate any element on the table.

The p-block's diagonal line, starting at boron, contains metalloids that exhibit both metal and nonmetal characteristics. Elements found to the left of this line are metals and form cations, whereas those on the right are nonmetals and form anions. Combining the group number with the octet rule helps predict an element's number of bonds.

Let's apply this knowledge to oxygen. Oxygen is in group 16, has six valence electrons, and is located to the right of the metal-nonmetal line, making it a nonmetal and forming an anion. According to the octet rule, oxygen forms two covalent bonds or an ion with a 2 minus charge.

Note that some transition metals, such as copper and iron, can create several cations with varying charges, also known as a variable charge.

Metals, metalloids, and nonmetals in the periodic table. A standard periodic table with a thin tall rectangle housing the elements in group 1 and 2. This block is labeled the s block. The transition metals are included in a squashed, wide rectangle ranging from groups 3 to 12. This block is labeled as the d block. A square completes the groups from 13 to 18 and is labeled the p block. The p block is divided by a diagonal red line which consists of metalloids. The metalloids that make up the line are boron, silicon, germanium, arsenic, antimony, tellurium and polonium. All the elements to the left of this line are blue, which indicates that they are metals. Except for hydrogen, all elements to the right of the line are green, which indicates that they are nonmetals. The lanthanides and actinides are shown as a separate rectangle below the first table which is labeled the f block and all the elements are blue.

Figure 1: Metals, metalloids, and nonmetals: The diagonal line cutting through the metalloids splits the table into metals, on the left, and nonmetals, on the right. Each block also organizes the elements based on their electron configuration.