Question

What is the term for the elements that belong to Groups IA-VIIIA (Groups \(1,2,\) and \(13-18) ?\)

Short answer

They are called the main-group elements or representative elements.

Step-by-step solution

Identifying the Groups

Groups IA, IIA, and IIIA through VIIIA correspond to a modern numbering system of periodic table groups. IA (1) and IIA (2) are the first two columns on the left of the periodic table, while IIIA (13) through VIIIA (18) are on the right side of the table.

Recognizing the Term

Groups IA-VIIIA are part of the s and p blocks of the periodic table. These groups are collectively known as the main-group elements or representative elements.

Key concepts

Periodic Table Groups

The periodic table is essentially a map used by chemists to organize elements. Each column, or periodic table group, is a collection of elements with similar properties. The groups are numbered, and the elements in each group share some chemical or physical characteristics.

Groups in the periodic table are arranged from left to right, starting with Group 1 (IA) on the far left, moving through to Group 18 (VIIIA) on the far right. The elements in each group have the same number of electrons in their outer electron shell, known as valence electrons, which is why they exhibit similar behavior.

For instance, elements found in Group 1, such as lithium, sodium, and potassium, all have one valence electron. This characteristic makes them very reactive, especially with water. On the other hand, the noble gases in Group 18 have eight valence electrons, making them stable and mostly inert. Understanding these groups helps predict how different elements will react with one another.

S Block Elements

The s block is the part of the periodic table containing the elements of Groups 1 and 2, along with helium in the first period. The outermost electrons for elements in the s block are in the s subshell. This configuration significantly influences their chemical properties.

• Group 1 (Alkali Metals): Includes lithium, sodium, and potassium. They are highly reactive due to their single valence electron, which they tend to lose easily to form positive ions (cations).
• Group 2 (Alkaline Earth Metals): Contains beryllium, magnesium, and calcium. These elements have two valence electrons and readily form cations with a 2+ charge by losing these electrons.

The s block elements are known for being very reactive, mainly because they only need to lose a small number of electrons to achieve a stable electron configuration. This is why you find them at the top of the reactivity series in chemistry.

P Block Elements

The p block is found on the right side of the periodic table, consisting of Groups 13 to 18. The elements in the p block have their outermost electrons in the p subshell, giving them a rich diversity of chemical behaviors.

• Group 13: Contains boron and elements like aluminum. This group is mostly metals and metalloids.
• Group 14: Includes carbon, a vital element for life, along with silicon and others. It features both nonmetals and metalloids.
• Group 15: Houses nitrogen and phosphorus, essential for biological processes, alongside heavier elements such as arsenic.
• Group 16 (Chalcogens): Includes oxygen, necessary for respiration, sulfur, and selenium.
• Group 17 (Halogens): Highly reactive nonmetals like fluorine and chlorine, which readily form salts.
• Group 18 (Noble Gases): Features inert gases such as helium, neon, and argon, characterized by their lack of reactivity due to full valence electron shells.

These elements display a range of properties and reactivities, from the highly reactive halogens to the nearly inert noble gases, making the p block one of the most diverse sections of the periodic table.