Modern Periodic table

Discover the elements of Modern periodic table and how they are arranged.

The elements

 Matter that is composed of a single type of atom is called an element . Certain elements like gold, silver, iron, mercury and tin have been known for hundreds of years. During the 18th and 19th centuries, scientists discovered many more. Some of the elements were even discovered during your lifetime !


Naming the elements

Most element names and symbols come from Latin or Greek. For instance :


Element Atomic symbol Origin of the word

Gold At Latin word Aurum which means “bright dawn”

Mercury Hg Greek word Hydrargyrum meaning “cash money”

Chlorine Cl Greek word Chloros which means “green”

Neon not Greek word Neos which means “new” or “different”

Some names also come from famous scientists like:

Element Atomic symbol Origin of the word

Curium CM Pierre and Marie Curie (research on radioactivity)

einsteinium Is Albert Einstein

Nobelium No Alfred Nobel (famous for creating the Nobel Prize)

Mendelevium md Dmitry Mendeleev (creator of the first periodic table)

Other elements take their names from places, such as:

Did you know?

Argentina takes its name from an element. Its name comes from the Latin word for money, Argentum , because the First Nations had given silver as a gift to the first 

 Modern Periodic Table of Element Modern Periodic Table of Elements is a visual and logical way to organize all the elements. In general, the creation of the first periodic table, in 1869, is attributed to the Russian scientist Dmitry Mendeleev. In Germany, later in the same year, Lothar Meyer also created an almost identical painting. Some people attribute the first classification to Alexandre-Emile Béguyer de Chancourtois .

Modern Periodic Table

The periodic table lists each element in a box giving its atomic symbol and atomic number. Sometimes the full name of the element and its atomic mass are also indicated. The image below shows a typical entry for calcium.

The number above the atomic symbol represents the atomic number. The atomic number is equal to the number of protons in the nucleus of the atom and determines which element is the atom. For example, any atom with exactly 20 protons in its nucleus is a calcium atom. The number of protons influences the chemical behavior of an element.

The atomic mass of an element refers to the mass of an element expressed in atomic mass unit ( u ). In general, this information is found at the bottom of an element’s box in the periodic table. Atomic mass is expressed as a decimal number because it is an average of the masses of the various isotopes of an element. Isotopes of an element have the same number of protons, but differ in their number of neutrons. For example, hydrogen has three natural isotopes. The most common isotope, protium , has no neutrons! Deuterium has one neutron and tritium has two.

The three naturally occurring isotopes of the hydrogen atom

Scientists have also created other highly unstable isotopes of hydrogen. The latter, which have up to 7 neutrons, do not exist in nature.

One can easily know the average number of neutrons of an element. Just subtract the number of protons (atomic number) from the atomic mass. For example, the atomic number of calcium is 20 and its atomic mass is 40.078 u. By subtracting 20 from 40 (after rounding the number off), we can determine that the average neutron count is 20.

The classification of elements

Mendeleev organized the periodic table according to the atomic mass of the elements, from smallest to largest. Next, he defined horizontal and vertical rows (or columns) to highlight elements that possess similar chemical properties. The horizontal lines are called periods . All elements of the same period have the same number of electron shells . Columns are called groups (or families).

Mendeleev also left a few blank spaces in his chart. He believed that some elements had not yet been discovered. These empty spaces were for undiscovered items. Mendeleev expected missing elements to have the same properties as other elements in the same column.

During the 1990s, many discoveries led to new elements. Mendeleev’s chart was adapted to arrive at the model we use today. The modern chart still includes the principles of families and periods today.

The groups of the periodic table are numbered from 1 to 18 . Elements in the same group generally have similar properties. For example, group 18 elements are all gases that do not readily react with other elements. Some groups sometimes have a name. For example, group 18 elements are called “ noble gases ”. 

Did you know?

Noble gases are so named because of their ability not to react with other elements. Like humans who keep calm and are considered noble.

The noble gas group in the periodic table of elements

The noble gas group in the Periodic Table of Elements (Source: Let’s Talk Science using an image by Dmarcus100 [CC-BY-SA] via Wikimedia Commons ).

Except for hydrogen, the elements on the left side of the periodic table are metals . At room temperature, metals are solid except for mercury, which is liquid. Metals are also malleable and stretchable . That is, they can be formed. Metals also have a shiny appearance. They are good conductors of heat and electricity.

The elements on the right side of the periodic table are nonmetals. At room temperature, nonmetals can be solid, liquid, or gaseous. They are poor conductors of heat and electricity.

Elements that possess certain metallic and non-metallic properties are called metalloids (eg, silicon, arsenic, etc.).

Sometimes we call the elements in groups 3 through 12 the d block . These elements are also known as transition elements .

Elements of the d-block from the periodic table of elements

The d-block elements of the Periodic Table of Elements (Source: Let’s Talk Science using an image by Dmarcus100 [CC-BY-SA] via Wikimedia Commons ).

At the bottom of the periodic table, there are two rows. These are the lanthanides and the actinides. The lanthanides are fifteen metallic elements that have an atomic number between 57 and 71. The lanthanide elements, along with the two group 3 elements, scandium and yttrium, are often referred to as the rare earth elements . Lanthanides are found naturally on Earth. Actinides are quite different. All actinide elements are radioactive and some are not found in nature. Some of the elements with a high atomic number can only be created in the laboratory.

The lanthanides and actinides of the periodic table of elements

The lanthanides and actinides of the Periodic Table of Elements (Source: Let’s Talk Science using an image by Dmarcus100 [CC-BY-SA] via Wikimedia Commons ).

Periodic Table Trends

In a group, from top to bottom, the size or radius of an atom increases. Elements have more shells of electrons, resulting in larger atoms. In one period, from left to right, the size of the atom decreases. More protons pull electrons towards the nucleus.

Relative sizes of atoms

Relative sizes of atoms (Source: Let’s Talk Science using an image from Encyclopedia Britannica).

Electronegativity is the chemical property that describes the tendency of an atom to form bonds with others . Generally speaking, from top to bottom, electronegativity decreases within a family and increases, left to right, within a period. The elements with the highest electronegativity are found in the upper right part of the table (except for the noble gases). This is because nonmetals have high electronegativity. They tend to attract electrons from other atoms. Whereas metals tend to lose electrons easily.

Assign loads to an element

Stable atoms must lose or gain electrons to be electrically charged. There are two types of electrical charges. There are positive charges (+) and negative charges (-). Substances with the same charge repel each other. Whereas substances with opposite charges attract each other. They act like magnets!

Atoms of some elements can lose or gain electrons more easily than others. For example, group 1 elements (Li, Na, or K) can easily lose an electron, giving them a charge of +1 . Group 17 elements (Cl, Br, I) can easily gain an electron, giving them a charge of -1 . An atom or a molecule that has a charge is called an ion . When an atom or a molecule has more electrons than protons, we get a negatively charged ion called an anion . An ion that has a positive charge, i.e. an atom or molecule that has more protons than electrons, is a cation .

Each group in Modern periodic table has a specific charge commonly associated with its ions. Transition elements, lanthanides and actinides are the exceptions to this rule. Below you will find the loads of the different groups in the table.

Band 1 2 3 Transition elements, lanthanides and actinides 15 16 17 18

Charge +1 +2 +3 Variation -3 -2 -1 0

You may have noticed that group 18 elements have a charge of 0. These elements are very stable and do not easily gain or lose electrons.

Modern Periodic table

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