[Chemistry Class Notes] Metals, Non-Metals, and Metalloids Pdf for Exam

The tabular arrangement of the chemical elements by increasing atomic number to see the trends in their properties is called a periodic table. The Russian scientist Dmitri Mendeleev is credited with inventing the periodic table (1869). The modern table is derived from Mendeleev’s form of the table, but has significant differences.  Mendeleev’s version placed and ordered the elements according to increasing atomic weight rather than atomic number. 

How do we figure out the position of elements in the periodic table? Elements are natural extracts that we yield naturally and some are made synthetically but the original form has to be extracted no matter what. The most important characteristic of an element is that it cannot be broken down into any other substance and that is why it is written that it is extracted in its original form. Each element, which is about 100, has its own type of atom because every matter contains atoms and then ultimately everything in the universe contains at least one or more elements. 

The periodic table then places or lists all the known elements together with the similar properties and in a sequential manner. Periodic table helps us to identify those elements based on their property which can also indicate to us their weight, whether it is a normal element or comes under noble category etc.

Organization of the Elements

The arrangement and structure of the periodic table makes it easier and accessible for us to see the link and relationship between the elements at a glance, it is helpful in quickly locating the elements and in turn attach our own heuristics to learn the table as well. It is a basic step before we enter the chapter and read about the elements in detail, so the periodic table gives us a brief idea about the elements in the shortest form possible.

 

Elements and Classification

The elements have one form of classification where they are broadly classified as metals, nonmetals, and metalloids. Metals and non-metals are generally heard of but here we will also study the intermediate type of elements called metalloids. This type of classification is based on the shared physical and chemical properties.

 

A jagged black line in a periodic table (see figure below) along the right side of the table separates the metals from the nonmetals. To the right of the line lie nonmetals, the metals are to the left of the line(except hydrogen, which is a nonmetal), and the elements which lie immediately adjacent to the line are the metalloids.

Metals – What are Metals?

A metal is generally a hard solid substance that has a shiny luster and it conducts heat and electricity. Metals are good conductors of heat and electricity. Silver is the best conductor of heat. Metals also possess malleability, that is they can be hammered into sheets. Metals being ductile can be drawn into wire. At room temperature, most of the metals are solids and have a characteristic silvery shine (except for mercury, which is a liquid). 

The melting points of metals are usually high but gallium and caesium are those metals having such low melting points that they will melt if you keep them on your palm. Another exception to general characteristics of metals is alkali metals such as lithium, sodium, potassium which are so soft that they can be cut with a knife. Also, they have low densities and low melting points. Lead, mercury, titanium, chromium are bad conductors of heat. Bismuth is the poorest conductor of heat.

Metals Definition

A metal can be defined chemically as an element that readily forms positive ions (cations) and has metallic bonds. They tend to lose electrons easily. While the traditional definition focuses on the bulk properties of metals, they are sometimes also described as a lattice of positive ions surrounded by a cloud of delocalized electrons.

The Reactivity Series

The reactivity series is a series of metals where the arrangement is done in the order of their decreasing activities. It is developed after performing displacement experiments.

Non-Metals – What are Nonmetals?

Nonmetals are those elements that generally lack the properties of metals or have their properties opposite to that of metals. Their thermal and electrical conductivities are usually poor. They are brittle and do not possess the properties of malleability and ductility. Elemental nonmetals mostly are in a gaseous state at room temperature, while others are solids. Bromine is a non-metal which is liquid. Non-metals lack the shiny lustre except iodine. 

Generally, nonmetals have low melting and boiling points. Carbon is a nonmetal that can exist in different forms called allotropes. Diamond is an allotrope of carbon and is the hardest natural substance known and has a very high melting and boiling point. So it is an exception in the case of nonmetals. Also graphite, another allotrope of carbon is a good conductor of electricity which is another exception. Non-metals are less dense as compared to metals.

Nonmetals Definition

Non-metals are elements that form negative ions(anions) by accepting or gaining electrons. They generally have 4, 5, 6, or 7 electrons in their outermost shell so they tend to gain electrons during chemical reactions.

Metalloids – What are Metalloids?

The metalloids are intermediate in their properties between metals and nonmetals. Taking physical properties into consideration, they are more like nonmetals, but under certain circumstances, contrary to the expected behavior many of them can be made to conduct electricity. These semiconductors find their use in computers and other electronic devices. 

They can have a dull or metallic appearance. In a periodic table, these elements run diagonally. They are usually brittle. They form alloys with metals. They can both gain or lose electrons in a chemical reaction. Due to their unique properties, they find their use as catalysts, biological agents, flame retardants, alloys, and semiconductors in industries. Boron, silicon, germanium, arsenic, tellurium, and antimony are some commonly known metalloids.

Metalloids Definition

Metalloid, in chemistry, is a term that describes a chemical element forming a simple substance having properties intermediate between those of a typical metal and a typical nonmetal. They are often called semi-metals.

Comparative Study of Metals, Nonmetals, and Metalloids

In turn, there are Four New Elements that are  Added to the Periodic Table

Periods

There are a total of seven rows of the periodic table, which are called periods The increase is from left to right across a period. Elements on the left side of a period are metals and those on the right side are nonmetals. Moving down a period on the table adds a new electron shell.

Groups

The columns are addressed as groups or families. Right from the alkali metals to Noble gases, groups are numbered from 1 to 18 with the former being for the alkali metals and the latter for Noble gases. Elements with a  common group share a valence electron configuration. Elements display a pattern with respect to the atomic radius, electronegativity, and ionization energy. The atomic radius increases as the elements in succession gain an electron energy level.

Similarly, as we go down the Electronegativity decreases as we add an electron shell which basically pushes the valence electrons from the nucleus. Usually, elements have successively lower ionization energies when we move down the group, the reason being the easier removal of an electron from the outermost shell. 

Blocks

This section of the periodic table indicates the outer electron subshell of the atom. As we begin, we come across the S- Block which includes two groups named hydrogen, and helium. Then comes the p-block which includes elements or groups 13 to 18. Moving ahead we come to the d-block which includes groups 3 to 12, which are transition metals. Lanthanides and actinides are categorized under f-block, which is below the main body.

Conductivity

The ability to measure an aqueous solution to carry an electric current can be defined as conductivity. When put in a scientific manner it is the ability to transmit heat, sound, or electricity. So for eg. We can say that the conductivity in the water will be higher because of the concentration of ions. So, when we measure the conductivity of water, we basically and indirectly measure the concentrations of dissolved salts, bases, and acids. The conductance of a material. 

Ductility

This is defined as the ability of a material to be drawn or plastically deformed without fracture. It, therefore, indicates the softness or malleable the material is. The ductility of steel varies on the types and levels of alloying elements present. The quality or state of being ductile can be said as its shape changed without losing strength or breaking. When alloys are added to the metal, it improves hardness and strength can be improved without decreasing the ductility.

Malleability

the state of being malleable, or capable of being shaped, as by hammering or pressing, in simple words how a metal or anything can be moulded into any required shape without changing its properties is called the malleability of the element. Metal such as Gold, aluminium, and iron are examples among many other malleable elements that are used in our lives which we mould accordingly and use as per our convenience.

Are Metalloids Essential for Life?

Metalloids can be considered of vital importance to human health, plants, and all other living organisms. Some of the metalloids like boron, selenium, and silicon are beneficial or essential for healthy plant growth, whereas others, like arsenic and germanium, are highly toxic. Typically Metalloids have a metallic appearance but they are brittle, which is anything hard but is liable to break easily.  Along with this property, they also tend to be very good conductors of electricity.

Conclusion

This is all about the different elements and their types in the periodic table. Learn the different features of these types of elements and understand how they are categorized. Hence, focus on the properties and understand how they are organized to form a periodic table.