How to Read the Periodic Table

If you find the periodic table of the elements complicated and confusing, you are not alone! Understanding every function of the periodic table can be difficult, but knowing how to read will help you do well in science subjects. Let’s start by understanding the structure of the periodic table and see what information it provides about each element. Next, you can learn about each element. Finally, use the facts in the periodic table to find the number of neutrons in an atom.

Table of Contents

Understand the structure of the periodic table

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Read the periodic table from top left to bottom right. The elements are arranged in order of increasing atomic number as you read right and down the periodic table. The atomic number indicates how many protons are in an atom of that element. You will also notice the atomic mass increasing to the right. This means you can tell a lot about an element’s weight just by looking at its position on the periodic table.

Atomic mass increases to the right or down the periodic table because mass is calculated by adding up the protons and neutrons in each atom of the element. The number of protons increases with each element, and this means that the weight also increases.
Electrons are not included in the atomic mass because their contribution is so small compared to protons and neutrons. ^{[1] X Research Source}

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Notice that each element has 1 more proton than the element before it. You can tell this by looking at the atomic number. The atomic numbers are ordered from left to right. The elements are also arranged in groups, so you’ll see gaps on the periodic table. ^{[2] X Research Source}

For example, the first row has the element Hydrogen with atomic number 1, and Helium with atomic number 2. However, they are opposite each other at the top of the table because they belong to different groups.

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Identify groups, which include elements that share physical and chemical properties. The groups will be arranged in a vertical column. In most cases, the groups are also filled with the same color. This will help you identify which elements have similar physical and chemical properties, so you can infer their properties. ^{[3] X Research Source} Each element in a particular group will have the same number of electrons in its outer orbital. ^{[4] X Research Sources}

Most elements are in the same group, but hydrogen can be classified as either the halogen group or the alkali metal group. In some tables, Hydrogen appears in both groups.
Usually, columns will be numbered 1-18, listed above or below the periodic table. These numbers can be written in Roman numerals (IA), Arabic numerals 1A), or using only numbers (1).
When you look from top to bottom, you are “reading in a group”.

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Understand why there are gaps on the periodic table. The elements are not only ordered by atomic number, but also arranged in groups that share similar physical and chemical properties. This will help you better understand the characteristics of each element. Elements do not always fit in groups as they increase in number, so the periodic table has gaps. ^{[5] X Research Sources}

For example, the first 3 rows have gaps, since transition metals only appear on the periodic table after atomic number 21.
Similarly, elements 57 to 71, which are rare earth elements, are usually represented as a subset in the lower right of the periodic table.

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Notice that each row is called a cycle. All elements in a period have the same number of atomic orbitals where the electrons are located. The number of orbitals will be equal to the number of periods. There are 7 rows in all, which means there are 7 cycles. ^{[6] X Research Sources}

For example, elements in period 1 have 1 orbital, elements in period 7 have 7 orbitals.
In most cases, they are numbered 1-7 from the top left of the periodic table.
When you read a row from left to right, you are “reading in a cycle”.

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Distinguish between metallic, nonmetallic and nonmetallic elements. You can better understand the properties of an element by determining the element’s type. Fortunately, most periodic tables use color to indicate whether an element is a metal, a metalloid, or a nonmetal. You’ll see metals appear on the left side of the periodic table, while nonmetals appear on the right. The metalloids are sandwiched between metals and nonmetals. ^{[7] X Research Sources}

Remember that hydrogen can be classified as a halogen or an alkali metal because of its properties, so it may appear on both sides of the periodic table or may be colored differently.
Elements are labeled as metals if they have a metallic luster, are solid at room temperature, are good electrical and thermal conductors, and are malleable and easy to spin.
Elements are considered nonmetals if they have no metallic luster, do not conduct electricity or heat, and are not malleable. These elements are usually gaseous at room temperature, but they can also become solid or liquid at certain temperatures.
Elements are labeled as nonmetals if they have the properties of both metals and nonmetals. ^{[8] X Research Sources}

Learning about the elements

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Identify the 1- or 2-letter symbol of the element. The element’s symbol usually appears in the center of the cell, printed in large font. The symbol stands for element names that are standardized in different languages. When you do experiments or solve chemical equations, you will have to use element symbols, so it is important that you are familiar with them. ^{[9] X Research Source}

The symbols of the elements are often derived from the Latin names of the elements, but can also be derived from generally accepted names, especially new elements. For example, the symbol for Helium is He, which is almost the same as the common name. There is also a symbol for elements such as iron (iron in English) which is Fe which is a bit difficult to recognize at first.

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Find the full name of the element if given. This is the name of the element that you will use when writing it down. For example, “Helium” and “Carbon” are the names of the elements. Usually it will appear just below the symbol, but can also be placed somewhere else. ^{[10] X Research Source}

Some periodic tables of chemical elements may not have full names but only symbols.

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Find the atomic number. The atomic number is usually written on the top, center, or corner, but it can be below the element’s symbol or name. The atomic numbers follow each other from 1-118. ^{[11] X Research Source}

The atomic number is an integer, not a decimal.

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Understand that the atomic number is the number of protons in an atom. All atoms of an element have the same number of protons. Unlike with electrons, an atom cannot lose or gain more protons. Otherwise, the element will mutate! ^{[12] X Research Source}

You will also use the atomic number to find the number of electrons and neutrons!

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Know that elements usually have the same number of electrons and protons. The exception here is when they are ionized. Protons have a positive charge and electrons have a negative charge. Normal atoms have no charge, meaning they have an equal number of electrons and protons. However, an atom can lose or gain electrons, i.e. it is ionized. ^{[13] X Research Source}

Ions carry an electric charge. If an ion has more protons, it will carry a positive charge and is represented by a plus sign next to the ion’s symbol. If the ion has more electrons, it will carry a negative charge, represented by a minus sign.
You won’t see a plus or minus sign if the element is not an ion.

Use atomic weight to calculate the number of neutrons

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Find the atomic weight. Atomic weights are usually listed at the bottom of the box, below the element symbol. Atomic weight is the total weight of the particles in the nucleus of an atom, including protons and neutrons. However, ions complicate calculations, so the atomic weight is the average atomic mass of the element and the atomic mass of its ions. ^{[14] X Research Source}

Since the weights are averaged, most elements will have their atomic weights included in decimals.
Although it seems that atomic weight increases from top left to bottom right, this is not always the case.

Determine the mass number of the element you are studying. You can find the mass number by rounding the atomic mass to the nearest whole number. This is based on the fact that the weight of an atom is the average of all the atomic masses of that element plus ions. ^{[15] X Research Source}

For example, the atomic weight of Carbon is 12,011, rounded to 12. Similarly, the mass of iron is 55,847, rounded to 56.

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Subtract the atomic number from the mass number to find the number of neutrons. The mass number is calculated by adding the numbers of protons and neutrons. This makes it easy to find the number of neutrons in an atom by subtracting the number of protons from the mass number! ^{[16] X Research Source}

Use the formula: Neutron = Mass Number – Proton
For example, Carbon’s mass number is 12, and it has 6 protons. Since 12 – 6 = 6, you would know Carbon has 6 neutrons.
As another example, the mass number of Iron is 56 and iron has 26 protons. Since 56 – 26 = 30, you would know Iron has 30 neutrons.
Isotopes of an atom will have a different number of neutrons, so it will change the weight of the atom.

Advice

The colors in the periodic tables may be different, but the information in them is the same.
Reading the periodic table is difficult for many people! Don’t be discouraged if you struggle to learn how to use it.
Some periodic tables can simplify information, such as providing only symbols and atomic numbers. Find out which periodic table meets your needs.

Steps

Understand the structure of the periodic table

Learning about the elements

Use atomic weight to calculate the number of neutrons

Advice

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