Question

In the periodic table, calcium, element 20 , is surrounded by elements \(12,19,21\), and 38 . Which of these have physical and chemical properties most resembling calcium?

Short answer

Magnesium (element 12) and strontium (element 38) have the most similar physical and chemical properties to calcium (element 20) because they are in the same group 2 of the periodic table.

Step-by-step solution

Understand the Periodic Table Organization

The periodic table is organized such that elements with similar physical and chemical properties are in the same group (column). These groups are numbered from 1 to 18. Calcium is in the second column of the periodic table, which is group 2.

Identify the Group of Elements

From the given elements, we need to identify which ones are in the same group as calcium. Calcium (element 20) is in group 2. We look at the group number for each of the surrounding elements: 12 (magnesium), 19 (potassium), 21 (scandium), and 38 (strontium). Elements in the same group as calcium will have similar properties.

Compare Properties Based on the Group

By comparing the group numbers, we find that magnesium (element 12) and strontium (element 38) are also in group 2, sharing similar properties with calcium. Potassium (element 19) is in group 1, and scandium (element 21) is in group 3, therefore they do not have the most similar properties to calcium.

Key concepts

Periodic Table Organization

The periodic table is a comprehensive grid that represents the elements in an ordered, systematic way. Elements are arranged from left to right and top to bottom in order of increasing atomic number. This layout isn’t random; Dmitri Mendeleev, the father of the periodic table, designed it so that elements with similar properties fall into the same columns, known as groups. These groups tell us quite a bit about the elements contained within them.

For instance, Group 1 elements, excluding hydrogen, are known as the alkali metals, and Group 18 elements are called noble gases because of their lack of reactivity. Understanding the periodic table's structure helps predict how an element might behave in chemical reactions and what properties it may have. Each group is numbered 1 through 18, reflecting the newer IUPAC nomenclature, which replaces the older group labeling method using Roman numerals and letters.

Chemical Properties of Elements

Chemical properties of an element are determined largely by the electrons in the outermost energy level of an atom, or the valence electrons. These properties dictate how an element will engage in chemical reactions, mainly how it bonds with other elements. For elements in the same group, their valence electron configuration is similar, leading to comparable reactivity and chemical behavior.

For example, alkali metals (Group 1) have a single valence electron, which makes them highly reactive. They tend to lose this electron to achieve a more stable electron configuration, forming ionic bonds with nonmetals. On the other hand, noble gases have full valence electron shells, which is why they are generally unreactive. An understanding of these properties helps scientists and chemists predict how elements will interact with one another and form compounds.

Physical Properties of Elements

Physical properties can be observed without changing the identity of the element, and they include characteristics like color, density, melting and boiling points, and electrical conductivity. Looking at the periodic table, elements in the same group tend to display trends in physical properties.

For instance, within a group, as the atomic number increases, there’s a trend of increasing atomic radius, meaning atoms generally get larger going down a group. This trend affects other physical properties such as melting and boiling points. The alkali metals again serve as an excellent example: they have low densities and low melting points that decrease further down the group. Knowing these trends helps in predicting and explaining the behavior of elements in different physical states and conditions. It's a crucial aspect for disciplines such as materials science and engineering, where understanding the properties of an element is essential in selecting the right material for the job.