Question

List the number of valence electrons for each family in the periodic table, and explain the relationship between the number of valence electrons and the resulting chemistry of the elements in the family. $$\begin{array}{ll}{\text { a. alkali metals }} & {\text { b. alkaline earth metals }} \\ {\text { c. halogens }} & {\text { d. oxygen family }}\end{array}$$

Short answer

Alkali metals have 1 valence electron, alkaline earth metals have 2, halogens have 7, and the oxygen family has 6. The number of valence electrons influences the element's reactivity and the types of bonds it will form to achieve a stable electron configuration.

Step-by-step solution

Identify Valence Electrons in Alkali Metals

Alkali metals belong to group 1 of the periodic table and have 1 valence electron. These elements readily lose their single valence electron, which results in a +1 oxidation state, making them highly reactive, especially with halogens to form salts.

Identify Valence Electrons in Alkaline Earth Metals

Alkaline earth metals are located in group 2 of the periodic table and have 2 valence electrons. They tend to lose both valence electrons to achieve a stable electron configuration, resulting in a +2 oxidation state, and are reactive, although less so than alkali metals.

Identify Valence Electrons in Halogens

Halogens are in group 17 of the periodic table and have 7 valence electrons. With one electron short of a full octet, they are highly reactive, tending to gain an electron to achieve a stable configuration, which leads to a -1 oxidation state.

Identify Valence Electrons in Oxygen Family

The oxygen family, also known as chalcogens, belong to group 16 of the periodic table and have 6 valence electrons. These elements commonly gain or share two electrons to complete their valence shell, leading to various common oxidation states like -2 or +6.

Understand the Relationship Between Valence Electrons and Chemistry

The number of valence electrons determines an element's chemical properties and its ability to bond with other elements. Elements with fewer valence electrons tend to donate them in chemical reactions, while those with more valence electrons tend to accept electrons, influencing the type of ions they form and their reactivity.

Key concepts

Periodic Table Groups

Understanding the periodic table is fundamental to grasping the behaviors and properties of elements. One way the table is organized is into groups, which are the columns numbered from 1 to 18. Elements in the same group share similar chemical properties due to having the same number of valence electrons. Valence electrons are the outermost electrons and play a crucial role in chemical bonding and reactions.

For example, alkali metals in group 1 have a single valence electron, leading them to react similarly by losing that electron. In contrast, the halogens in group 17 have seven valence electrons, setting a pattern of high reactivity as they seek to gain an additional electron to achieve an octet. By examining these group trends, students can predict the chemical behavior and reactivity of an element based on its position in the periodic table.

Oxidation States

The oxidation state, sometimes referred to as oxidation number, is an indicator of the degree of oxidation of an atom in a chemical compound. It's an important concept because it helps to describe the transfer of electrons between atoms, specifically in redox reactions. The oxidation state is positive if electrons are lost, and negative when electrons are gained.

In the context of periodic table groups, alkali metals have an oxidation state of +1 because they typically lose one electron. Conversely, halogens have an oxidation state of -1 as they generally gain an electron. These oxidation states provide insight into the element's valence and how it might interact with other elements. Understanding oxidation states aids in predicting the formula of compounds and the outcomes of chemical reactions.

Element Reactivity

Element reactivity refers to the tendency of an element to engage in chemical reactions. Reactivity is heavily influenced by the number of valence electrons. Elements with few valence electrons, such as the alkali metals, are highly reactive because they can easily lose these electrons to attain a stable electron configuration. On the other hand, elements like halogens are also very reactive, as they avidly gain electrons to fill their outermost shell.

The knowledge of reactivity is crucial not just for understanding why certain elements react violently or form particular compounds, but also for practical applications. For instance, knowing the reactivity patterns can help in the safe storage of elements and in predicting the behavior of elements during a chemical synthesis. The exercise of listing the number of valence electrons in different families immensely helps in understanding these reactivity trends.