Periodic table how does it work

The periodic table of the elements contains a wide variety of information. Most tables list element symbols , atomic number, and atomic mass at a minimum. The periodic table is organized so you can see trends in element properties at a glance. Here is how to use a periodic table to gather information about the elements. The periodic table contains informative cells for each element arranged by increasing atomic number and chemical properties.

Each element's cell typically contains lots of important information about that element. Element symbols are abbreviations of the element's name. In some cases, the abbreviation comes from the element's Latin name. Each symbol is either one or two letters in length. Usually, the symbol is an abbreviation of the element name, but some symbols refer to older names of the elements for example, the symbol for silver is Ag, which refers to its old name, argentum. The modern periodic table is organized in order of increasing atomic number.

The atomic number is how many protons an atom of that element contains. The number of protons is the deciding factor when distinguishing one element from another.

Variation in the number of electrons or neutrons does not change the type of element. Changing number of electrons produces ions while changing the number of neutrons produces isotopes.

The element's atomic mass in atomic mass units is a weighted average mass of the element's isotopes. Sometimes a periodic table cites a single value for atomic weight. Other tables include two numbers, which represent a range of values. When a range is given, it's because the abundance of isotopes varies from one sampling location to another.

The atomic symbol for helium shown above is He. Lastly, the number in the bottom of each block is an elements atomic mass number. This number represents the average weight of a single atom of the element including protons and neutrons. In the case of helium, the atomic mass number is 4. Notice that each vertical column of the periodic table above is marked by a set of identifiers 1A, 2A, 3B, 4B ect These are known as groups.

The elements are arranged in these vertical groups because they share similar properties with each other. The elements are also arranged horizontally in rows called periods Shown above periods The elements in each period are not placed there at random.

Much like elements in a group, elements in a particular period all share similar properties. You may have noticed that the periodic table is also arranged in order of increasing atomic number.

Hydrogen H is the first element with an atomic number of 1. Beginning with hydrogen in the top left of the table, atomic numbers increase from left to right and top to bottom.

Mobile Newsletter chat subscribe. Physical Science. Chemical Elements. The periodic table could represent one of our best attempts at trying to organize the world. Cite This! Print Citation. At this time, less than half of the elements were known, and some of these had been given wrong data.

It was like working on a really difficult jigsaw puzzle with only half of the pieces and with some of the pieces misshapen. Mendeleev ultimately wrote the definitive chemistry textbook of his time, titled "Principles of Chemistry" two volumes, — , according to Khan Academy. As he was working on it, he came upon a significant discovery that would contribute greatly to the development of the current periodic table.

After writing the properties of the elements on cards, he began ordering them by increasing atomic weight, according to the Royal Society of Chemistry. This is when he noticed certain types of elements regularly appearing.

After intensely working on this "puzzle" for three days, Mendeleev said that he had a dream in which all of the elements fell into place as required. When he woke up, he immediately wrote them down on a piece of paper — only in one place did a correction seem necessary, he later said. Mendeleev arranged the elements according to both atomic weight and valence. Not only did he leave space for elements not yet discovered, but he predicted the properties of five of these elements and their compounds.

In , he presented the findings to the Russian Chemical Society.