What is Valency and Valence Electrons: Introduction
To explain valency and valence electrons: Valency and valence electrons are fundamental concepts in chemistry that play a significant role in understanding how atoms interact and form chemical compounds. Valency refers to the combined capacity of an atom, representing the number of electrons an atom can gain, lose, or share when forming compounds. Valence electrons, on the other hand, are the electrons in the outermost energy level or shell of an atom, determining its reactivity and bonding behavior. By understanding valency and valence electrons, we can predict the types of chemical bonds formed between atoms and comprehend the behavior and properties of elements and compounds. Let’s further know about the characteristics of valency and valence electrons.
Defining Valency
Valency is a fundamental concept in chemistry that describes the combined capacity of an atom. It refers to the number of electrons an atom can gain, lose, or share in order to achieve a stable electronic configuration. Valency is determined by the number of valence electrons, which are the electrons in the outermost energy level of an atom. The valence electrons participate in chemical bonding, either by forming covalent bonds through electron sharing or by transferring electrons to create ionic bonds. The following are the characteristics of valency:
Combining Capacity: Valency represents the combining capacity of an atom, indicating the number of electrons an atom can gain, lose, or share during chemical reactions.
Determined by Valence Electrons: Valency is determined by the number of valence electrons present in the outermost energy level or shell of an atom. The valence electrons are primarily responsible for the atom's chemical reactivity and bonding behavior.
Related to Group Number: Valency often correlates with the group number of an element in the periodic table for main group elements. Elements in the same group tend to have similar valencies due to their shared number of valence electrons.
Octet Rule: Valency is influenced by the octet rule, which states that atoms tend to gain, lose, or share electrons to achieve a stable electron configuration with eight electrons in the outermost energy level (except for hydrogen and helium, which follow the duet rule).
Bonding Behavior: Valency directly influences the types and number of chemical bonds an atom can form. It determines whether an atom will form ionic bonds by losing or gaining electrons, or covalent bonds by sharing electrons with other atoms.
Defining Valence Electrons
Valence electrons refer to the electrons present in the outermost energy level or shell of an atom. They are the electrons involved in the formation of chemical bonds and are responsible for the reactivity and bonding behavior of an atom. Valence electrons determine the combining capacity of an atom, as they can be gained, lost, or shared during chemical reactions to achieve a stable electron configuration. The number of valence electrons directly influences the types and number of bonds an atom can form. The following are the characteristics of valence electrons:
Determining Chemical Reactivity: Valence electrons primarily determine the chemical reactivity of an atom. The number and arrangement of valence electrons dictate how likely an atom is to gain, lose, or share electrons during chemical reactions to achieve a stable electron configuration.
Bond Formation: Valence electrons are involved in the formation of chemical bonds. They can be shared between atoms in covalent bonds or transferred from one atom to another in ionic bonds. The interaction of valence electrons governs the formation of molecules and compounds.
Influence on Oxidation States: Valence electrons determine the oxidation states or oxidation numbers of elements in compounds. The oxidation state signifies the number of electrons an atom has gained or lost in a chemical reaction.
Relationship with Group Number: The number of valence electrons often corresponds to the group number of an element in the periodic table for main group elements. Elements in the same group typically exhibit similar chemical properties due to their shared number of valence electrons.
Octet Rule: Valence electrons are involved in the fulfillment of the octet rule, where atoms tend to gain, lose, or share electrons to achieve a stable electron configuration with eight electrons in the outermost energy level (except for hydrogen and helium, which follow the duet rule).
Valency And Valence Electrons Differences
This table provides a concise overview of the main differences between valency and valence electrons. Understanding the distinctions between valency and valence electrons as both concepts are integral to predicting bonding patterns, chemical reactions, and properties of elements and compounds.
Summary
Valency refers to the combined capacity of an atom. It represents the number of electrons that an atom can gain, lose, or share when it forms chemical compounds. Valency is determined by the electronic configuration of an atom, specifically the number of valence electrons. At the same time, valence electrons are the electrons present in the outermost energy level or shell of an atom. These electrons are involved in the formation of chemical bonds. The valence electrons determine the reactivity and chemical behaviour of an element.
FAQs on Difference Between Valency and Valence Electrons for JEE Main 2024
1. Why are valence electrons important?
Valence electrons play a vital role in chemical reactions and the formation of chemical bonds. They determine the element's ability to gain, lose, or share electrons to form stable compounds. The interaction of valence electrons between atoms leads to the formation of various types of chemical bonds, such as covalent, ionic, and metallic bonds. The valence electrons also influence the physical and chemical properties of elements and are crucial in understanding the behavior and reactivity of elements and compounds.
2. How valence electrons can be obtained from the periodic table?
The number of valence electrons of an atom can often be determined by the group number (column number) in the periodic table. For elements in the main group (s-block and p-block), the group number represents the number of valence electrons. For example, elements in Group 1 (such as hydrogen and lithium) have 1 valence electron, while elements in Group 17 (such as fluorine and chlorine) have 7 valence electrons.
3. How is valency determined?
Valency is determined by the number of valence electrons present in the outermost energy level of an atom. The valence electrons are the electrons involved in bonding and chemical reactions. The valency of an atom is often equal to the number of electrons needed to achieve a full outer electron shell.
4. What is an example of valency?
An example of valency is the element sodium (Na). Sodium has an atomic number of 11, meaning it has 11 electrons in total. The electronic configuration of sodium is 2-8-1, with 2 electrons in the first energy level, 8 electrons in the second energy level, and 1 electron in the outermost third energy level. Since the outermost energy level has 1 electron, sodium has a valency of 1.
5. How do valence electrons determine the bonding behaviour of an atom?
Valence electrons determine the bonding behaviour of an atom by influencing the formation of chemical bonds. The number of valence electrons determines whether an atom will gain, lose, or share electrons to achieve a stable electron configuration. This behaviour determines whether an atom will form ionic bonds, where electrons are transferred, or covalent bonds, where electrons are shared with other atoms.