A periodic table is a graphical tool note for JEE/NEET. Where all the elements are displayed in increasing order of their atomic number.
It is called a period because after a ‘period’ (a certain number of boxes) the elements are grouped in a new row and form columns (groups or families) in which elements with similar chemical properties are placed.
This blog is written by one of my students, Ritika Rathore, a B.Sc first-year student. Thanks, Ritika
A periodic table is a graphic tool
Thus, for example, light metals are located on the left, heavy metals in the centre and non-metals on the right. The first periodic table was published in 1869 and was the work of Russian chemist Dmitry Mendeleev (1834–1907), who used 63 known elements to create it.
Periodic Properties of Elements:
Atomic Radius:
The atomic radii of the elements increase down and to the left in the periodic table. This is because: As the period increases, there are new electron shells, so the radius increases.
Over the same period, as the atomic number increases, the radius decreases due to the increasing attraction between the nucleus and the electrons.
ionization energy
Measures the energy required to release electrons and become a positive ion. Ionization energy moves up and to the right in the periodic table. The reason for this is that the atomic radius increases with the decrease of the period.
Metallic Characters:
Moves down and to the left on the periodic table. This is because the metallic nature of elements is given by: few electrons in the outer shell Largest atomic radius Low ionization energy
A chemical bond is a force that joins atoms to form chemical compounds. This association provides stability to the resulting compound. The energy required to break a chemical bond is called bond energy.
In this process, atoms give up or share electrons from the valence shell (the outer shell of an atom where its reactivity or tendency to form bonds is determined), and come together to form new homogeneous substances (do not mix ), through an indivisible physical system such as filtering or filtering.
A periodic table is a graphic tool.
It is a fact that the atoms that makeup matter come together in different ways that balance or share their natural electrical charges to reach more stable states than when they separate.
Chemical bonds form organic and inorganic molecules and are, therefore, part of the basis of the existence of living organisms. Similarly, chemical bonds can be broken under certain conditions.
This can happen by subjecting chemical compounds to high temperatures, applying electricity, or promoting chemical reactions with other compounds. For example, if we apply electricity to water it is possible to separate the chemical bonds between hydrogen and oxygen, a process called electrolysis.
Another example is adding a large amount of thermal energy to a protein, which will cause it to denature (lose the secondary structure of the protein) or break its bonds.
types of chemical bonds
There are three known types of chemical bonds, depending on the nature of the atoms involved:
covalent bond.
It occurs between non-metal atoms and atoms with similar (usually higher) electromagnetic charges, which come together and share a few pairs of electrons in their valence shell.
It is the major type of bond in organic molecules and can be of three types: simple (CC), double (C = C), and triple (C≡C), depending on the number of electrons shared.
Some examples of compounds with covalent bonds:
Benzene (C6H6)_
Methane (CH4)
Glucose (C6H12O6) _ _ _
Ammonia (NH3)
Freon (CFC)
In all forms of carbon (C): coal, diamonds, graphene, etc.
Some examples of compounds with ionic bonds:
Magnesium Oxide (MgO)
Copper sulfate (CuSO 4)
Potassium iodide (KI)
Manganese Chloride (MnCl 2)
Calcium Carbonate (CaCO 3)
Iron sulfide (Fe 2 S 3)
Some examples of metal-bonded compounds:
iron rods (Fe)
copper deposits (Cu)
Pure Gold Bars (Au)
Pure Silver Bars (Ag)
