Jonah Patel
The periodic table is a tabular array of chemical elements organized by atomic number, from the element with the lowest atomic number, hydrogen, to the highest, oganesson. The groups of the periodic table are displayed as vertical columns, numbered from 1 to 18, with the 14 f-block columns remaining unnumbered. Elements in the same group have similar chemical properties, which arise from the number of valence electrons present. The modern grouping system was first attempted by Russian chemist Dmitri Mendeleev in the late 19th century, based on the atomic weights of elements.
| Characteristics | Values |
|---|---|
| Number of groups | 18 |
| Group names | Numbers 1-18, with 14 f-block columns remaining unnumbered |
| Group 18 | Noble gases |
| Group 0 | Noble gases were placed in this group in 1902 |
| Groups in the old IUPAC system | Designated by letters A and B |
| Groups in the CAS system | Designated by letters A and B for main group and transition elements, respectively |
| Groups in the new IUPAC system | Numbered increasingly from left to right |
| Group members | Elements with similar chemical properties |
| Basis of grouping | The number of valence electrons, i.e., the number of electrons in the outermost shell of an atom |
| Subgroups | Based on similar characteristics and chemical properties |
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What You'll Learn
- The periodic table is made up of 18 groups, with 32 columns
- Groups are the columns of the table, and periods are the rows
- Elements in the same group have the same number of valence electrons
- Groups are numbered from 1-18, with the 14 f-block columns remaining unnumbered
- Elements in the same group have similar chemical characteristics
The periodic table is made up of 18 groups, with 32 columns
The periodic table is a tabular array of all chemical elements known to us. It is an organised array of all the chemical elements in order of increasing atomic numbers, i.e., the total number of protons in the atomic nucleus. The groups of the periodic table are displayed as vertical columns numbered from 1 to 18, with the 14 f-block columns remaining unnumbered. Together, they make up the 32 columns in the periodic table. The elements in a group have similar physical or chemical properties. These properties arise from the number of valence electrons present, i.e., the number of electrons in the outermost shell of an atom.
The periodic table is also known as the periodic table of elements and is an ordered arrangement of chemical elements into rows ("periods") and columns ("groups"). The modern group names are numbers 1–18. The old IUPAC system designated the letters A and B to the left (A) and right (B) parts of the table. In contrast, the new IUPAC scheme numbers the groups increasingly from left to right on the standard periodic table. The CAS system is most common in America and designates the letters A and B to main group elements (A) and transition elements (B).
The periodic table is divided into four roughly rectangular areas called blocks. Elements in the same group tend to show similar chemical characteristics. Vertical, horizontal, and diagonal trends characterise the periodic table. Metallic character increases when going down a group and from right to left across a period. Periods are the horizontal rows of the periodic table. There are seven periods in total, and each element in a period has the same number of atomic orbitals.
The elements in a group have very similar chemical properties, which arise from the number of valence electrons present. The arrangement of the elements in the periodic table comes from the electronic configuration of the elements. A quick way to understand an element's chemical and physical properties is to know the periodic trends. These trends tell you where the highest and lowest types of properties are concentrated on the periodic table.
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Groups are the columns of the table, and periods are the rows
The periodic table is a tabular array of chemical elements organised by atomic number. It is a depiction of the periodic law, which states that when elements are arranged in order of their atomic numbers, a recurrence of their properties is evident. This means that elements in the same column, or group, have similar properties.
Elements in the same group have the same number of valence electrons, which are the electrons in the outermost shell of an atom. The electron configuration of the atom determines the column or group. For example, elements with the same number of electrons in a particular subshell will fall into the same column. Elements in the same period have the same number of occupied electron shells.
Moving down the table, periods get longer because it takes more electrons to fill the larger and more complex outer levels. Metallic character increases going down a group and from right to left across a period.
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Elements in the same group have the same number of valence electrons
The periodic table is an organised array of all chemical elements arranged in order of increasing atomic number, ranging from the element with the lowest atomic number, hydrogen, to the highest, oganesson. The groups of the periodic table are displayed as vertical columns, numbered from 1 to 18.
The similarity in chemical properties within a group is also reflected in the trends in reactivity. For instance, the reactivity of alkali metals increases down the group as the outermost electron is further from the nucleus and is therefore more easily lost. On the other hand, the reactivity of halogens decreases down the group as the additional electron is less easily gained due to the increased distance from the nucleus.
The number of valence electrons also influences the types of bonds an element can form. Elements with one or two valence electrons, such as those in Groups 1 and 2, typically form ionic bonds by losing electrons. Elements with four or more valence electrons, such as those in Groups 14 to 17, often form covalent bonds by sharing electrons.
It is important to note that the transition metals in groups 3 to 12 and inner-transition metals (lanthanoids and actinoids) are exceptions to the general trend of valence electrons. The valence electron configurations of these metals are not described within the scope of the basic understanding of the periodic table.
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Groups are numbered from 1-18, with the 14 f-block columns remaining unnumbered
The periodic table is an organised array of all chemical elements, ordered by atomic number. The columns of the table represent groups, or families, of elements. These groups are numbered from 1 to 18, with the 14 f-block columns remaining unnumbered. The modern numbering system of "group 1" to "group 18" has been recommended by the International Union of Pure and Applied Chemistry (IUPAC) since 1988.
The old IUPAC system used the letters A and B to designate the left and right parts of the table, respectively. The CAS system, more common in America, also uses the letters A and B but designates them to main group elements (A) and transition elements (B). The new IUPAC scheme was developed to replace both systems as they used the same names for different meanings. The new system simply numbers the groups from left to right.
The elements in a group have similar chemical properties, which arise from the number of valence electrons present—that is, the number of electrons in the outermost shell of an atom. The arrangement of the elements in the periodic table comes from the electronic configuration of the elements. The f-block elements are unified by having one or more electrons in an inner f-orbital. The two series of f-block elements are the 4f series (lanthanoid) and the 5f series (actinoid).
Groups may also be identified using their topmost element or have a specific name. For example, group 16 is also described as the "oxygen group" or the "chalcogens". An exception is the "iron group", which usually refers to group 8, but in chemistry may also mean iron, cobalt, and nickel, or some other set of elements with similar chemical properties.
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Elements in the same group have similar chemical characteristics
The periodic table is a tabular array of all the chemical elements, organised by atomic number and arranged in columns (known as groups) and rows (periods). The groups of the periodic table are displayed as 18 vertical columns, numbered from 1 to 18, with the 14 f-block columns remaining unnumbered. The elements in a group have similar chemical properties, which arise from the number of valence electrons present.
The metallic character trend is opposite to the trend of ionization energy. The metallic character generally increases from top to bottom in a column because the atomic size increases, making the valence electrons less tightly held and easier to remove. Conversely, the metallic character generally decreases from left to right in a row because the atomic size decreases, making the valence electrons more tightly held and difficult to remove. The ionization energy and electronegativity generally increase from left to right in a row and from bottom to top in a column.
The periodic table is a powerful tool for understanding the behaviour of elements. By knowing the location of an element on the periodic table, we can anticipate how it might behave in nature or when mixed with other substances.
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Frequently asked questions
The constitute groups of the periodic table are the vertical columns of the table, numbered from 1 to 18, with the 14 f-block columns remaining unnumbered. The groups are also known as families, and the elements within them share similar physical and chemical properties.
The rows of the periodic table are called periods. There are 7 periods, plus the lanthanides and actinides. The elements in a period have the same number of atomic orbitals.
Group names include the alkali metals, alkaline earth metals, halogens, and noble gases.
