Using the periodic table above, how many electrons does oxygen have in its valence shell? How many shells of electrons does oxygen have? H
ow many other elements would oxygen likely bond with
The Correct Answer and Explanation is:
How many electrons does oxygen have in its valence shell?
6
How many shells of electrons does oxygen have?
2
How many other elements would oxygen likely bond with?
2
Explanation
The periodic table is a powerful tool that organizes elements based on their atomic structure and chemical properties. By understanding its layout, we can deduce key information about an element, such as its electron configuration and bonding behavior, without needing to memorize individual facts for each one. Let’s analyze oxygen (O) using the table provided.
1. Valence Electrons
The number of valence electrons—the electrons in the outermost energy shell of an atom—is crucial as it determines an element’s chemical reactivity. For main-group elements (Groups 1-2 and 13-18), the number of valence electrons can be determined from the group number. Oxygen (O) is located in Group 16. For groups 13 through 18, we can find the number of valence electrons by subtracting 10 from the group number. Therefore, oxygen has 16 – 10 = 6 valence electrons. These six electrons are what oxygen uses to interact and form bonds with other atoms.
2. Electron Shells
The rows of the periodic table are called periods. The period number corresponds to the number of electron shells (or principal energy levels) an atom of that element possesses. Locating oxygen on the table, we find it in the second row, or Period 2. This indicates that oxygen’s electrons are distributed across 2 electron shells. The first shell is full with two electrons, and the second, outermost (valence) shell contains the remaining six electrons.
3. Bonding Capacity (Valency)
Atoms tend to form chemical bonds to achieve a more stable electron configuration, typically by filling their valence shell. This principle is known as the octet rule, which states that atoms are most stable when they have eight valence electrons, similar to the noble gases (Group 18).
Since oxygen has 6 valence electrons, it needs to gain 2 more electrons to achieve a stable octet. The most common way for a nonmetal like oxygen to do this is by forming covalent bonds, where it shares electrons with other atoms. The number of electrons an atom needs to gain or share to complete its octet determines its valency, or the number of bonds it typically forms. Because oxygen needs two electrons, its valency is 2. This means an oxygen atom will likely form 2 covalent bonds. For example, in a water molecule (H₂O), a single oxygen atom forms one bond with each of the two hydrogen atoms.
