The Periodic Table Periods

The Periodic Table Periods

The Periodic Table Periods

The Periodic Table Periods: is a tabular arrangement in which all the elements arrange according to their chemical properties. There are 18 groups and 7 periods in the modern periodic table. Dmitri Mendeleev started the arrangement of atoms according to their atomic number.

List of Elements of the Periodic Table

Group 1 (alkali metals i.e. alkene)

Alkali metals are a series of elements in group 1 of the periodic table. This series includes elements such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).


• Alkali metals are silver-color (cesium is golden in color), soft, low-density metals.

•They have the lowest ionization energy. This makes them very reactive and they are very active metals.

• Because of their reactivity, they are naturally ionic compounds and not in the elemental state.

• Alkali metals readily react with halogens to form ionic salts, such as sodium chloride (NaCl).

• They react with water to release hydrogen gas.

Group 2 – Alkaline terrestrial metals

Series group 2 of the periodic table includes the elements beryllium (Be), magnesium (Mg), strontium (Sr), calcium (Ca), barium (Ba), and radium (Ra).


• Alkaline terrestrial metals are silver-color, soft, low-density metals, although they are slightly harder than alkali metals.

• All these elements have a valency of two electrons and tend to lose both to form ions with a two-plus charge.

•Beryllium is the least metallic element of this group and tends to form covalent bonds in its compounds.

• They react easily with halogens to form ionic salts and can react slowly with water

Group 13 (Boron Group)

The elements in group 13 of the periodic table are boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl).


• In this group, we see a change towards non-metallic nature. Boron is a metalloid, it has characteristics between metals and non-metals, and the rest of the group are metals.

• The valency of these elements is three electrons. Metals can lose all three electrons to form ions with a three-plus charge in ionic compounds.

• Aluminum is the third most abundant element in the Earth’s crust (7.4 percent) and is widely use in packaging materials. Aluminum is an active metal, but the stable oxide forms a protective coating on the metal that makes it resistant to corrosion.

Group 14 (Carbon Group)

Group 14 of the periodic table includes the elements carbon (C), silicon (Si), germanium (Ge), tin (Sn), and lead (Pb).


• The nonmetals in this group are carbon, two metalloids, and a mixed type of element with two metals. Its general characteristic is that of four electrons.

• Two metals, tin, and lead are unreactive metals and both can form ions in ionic compounds with a two-plus or four-plus charge.

• Carbon forms four covalent bonds in compounds instead of monatomic ions. In the elemental state, it has many forms, the most famous of which are graphite and diamond.

• Silicon is similar to carbon in some respects, forming four covalent bonds, but it does not form a wide range of compounds. Silicon is the second most abundant element in the Earth’s crust (25.7 percent) and we surrounding by silicon-rich materials like bricks, pottery, porcelain, lubricants, sealants, computer chips, and solar cells.

• The simplest oxide, silicon dioxide (SiO2) or silica, is a constituent of many rocks and minerals.

Group 15 (Nitrogen Group)

The nitrogen group is a series of elements in group 15 (formerly group V) of the periodic table. It includes phosphorus (P), nitrogen (N), arsenic (As), and bismuth (Bi), antimony (Sb), elements. The collective name pnictogens are also sometimes using for the elements of this group.


• All these elements have a valency of five electrons. Nitrogen and phosphorus are nonmetals. They can gain three electrons to form fairly unstable ions with the nitride and phosphide ions.

• Nitrogen, as a diatomic molecule, is a major component of air and both elements are essential for life. Nitrogen accounts for about 3 percent by weight and phosphorus about 1.2 percent in the human body. Commercially, these elements are important for fertilizers. Arsenic and antimony are metalloids, and bismuth is the only metal in the group. Bismuth can lose three electrons to form an ion with a three-plus charge.

• Bismuth is also a completely stable element that does not decay radioactively to other simpler elements.

Group 17 (Halogen)

Halogens are elements in group 17 (formerly group VII or VIIa) of the periodic table. They are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At).


• All these elements have a valency of seven electrons.
• This group is the first group consisting entirely of nonmetals.
• They exist in their natural state as diatomic molecules.
• At room temperature, fluorine and chlorine exist as gases, bromine is a liquid, and iodine is a solid.
• Halogens are highly reactive, and therefore can be harmful or fatal to biological organisms in sufficient quantities.
• In their elemental state, halogens are oxidizing agents and are use in bleach.

Group 18 (Noble Gas)

The noble gases and chemical elements include in the eighteenth group of the periodic table. They are helium, argon, krypton, neon, radon, and xenon. They are also sometimes calls inert gases or rare gases.


• Noble gases are all non-metals and are characterize by orbitals completely filled with electrons.

• They exist as monoatomic gases at room temperature, even those with large atomic masses. This is because they have very weak intermolecular forces of attraction, and consequently have very low melting and boiling points.

• Krypton and xenon are the only noble gases that form any compound. These elements can do this because they have the ability to form an extended octet by accepting electrons into an empty subshell.

Mendeleev’s table

It was publish by Mendeleev in 1869, using atomic weights to arrange the elements with reasonable accuracy in his time. The atomic mass worked well enough to allow Mendeleev to accurately predict the characteristics of the missing elements.
The atomic number is the complete definition of an element and gives a factual basis for the order of the periodic table.
Mendeleev realized that the physical and chemical properties of elements were related to their atomic masses in a ‘periodic’ manner, and arranged them so that groups of elements with similar properties lay in vertical columns in his table. The modern-day periodic table has evolved from Mendeleev’s initial 63 elements.

Newlands’ law of octaves

The Law of the Octaves, in Chemistry, by the English chemist J.A.R. Newlands state in 1865 that if the chemical elements were arrange according to increasing atomic mass, then elements with similar physical and chemical properties would appear after every interval of seven. In 1864 Newlands attempted to classify the elements.

There are seven musical notes in music. Every eighth is identical. Similarly, Newland said that the eighth element starting with a given element repeats like an eighth of an octave of music. That is why their relationship is call the law of octaves.

  1. Lithium, sodium, and potassium are closely related to each other in Newland’s table of elements.
  2. Fluorine and chlorine or oxygen and sulfur were place near each other.
    Note: This classification worked well with elements with smaller atomic weights but failed for elements with larger atomic weights.