Royal Chemistry academy

  ATOMIC RADIUS Atomic radius is defined as the distance from the center of the nucleus to the outer most shell of electrons.  Probability of finding the electron is never zero even at large distance from the nucleus. Based on probability concept, an atom doesn't have well defined boundary. Hence it is very difficult to determine the atomic radius.  Atomic radius is taken as the effective size which is the distance of the closest approach of one atom to another atom in a bonding state.  The atomic radius can be determined as (a) Covalent radius (b) Vander waal's radius (c) Metallic radius (d) Ionic radius Covalent radius One half of the inter-nuclear distance between the two covalently bonded atom is called covalent radius.  Covalent radius can be determined in case of the atoms which are attached to each other by covalent bond.  r covalent = Inter-nuclear distance between two covalently bonded atoms / 2 (i) For homoatomic molecules d A-A = r A + r A Or,...

  Periodic table is divide into 4  blocks known as S, p, d, f  blocks. The classification of the elements depends upon the type of sub-shell in which last electron of the element enters.  S - Block elements   The element in which last electron enters into s - subshell  are called s - block element.  The general electronic configuration of s - block elements are  ns 1-2   .  The s - block elements are present in the left side of the periodic table.  Group 1 and Group 2 elements as well as Helium of zero group are known as the s - block elements. All s - block elements are normal elements. Characteristics of s - block elements (i) The elements have low ionization energy.  (ii) They are soft metal having low melting and boiling point.  (iii) They are highly reactive.  (iv) They are good reducing agents.  (v) They give to the flame.  p - block elements The elements in which last electrons enters into p - subshel...

The vertical columns starting from top to bottom are called groups.  There are 18 groups in the periodic table and the groups are denoted by IA to VIIA, IB to VIIB, VIII (three columns), Zero group.  According to latest convention the groups are number as 1 to 18. CHARACTERISTICS OF GROUPS (1) Valency  :- Valency of all the elements in a group are same.  Ex:- All the elements of group 1 , i.e. Li, Na, k, Rb, Cs, Fr have the valency one.  (2) Similar properties :- All the elements of same group have similar properties as they have same valencies.  Ex:-All elements of group 1 have low ionization energy.  (3) Prediction of properties  :- The group number of an element helps to predict the property of that element, by knowing the property of one element and the properties of other elements in the same group can be predicted.  (4) Gradation of properties  :- The elements of same group have gradually change in properties with increasing in ato...

In Long form periodic table elements have been arranged in the increasing order of their atomic mass and also based on electronic configuration.  This periodic table consists of (i) 7 horizontal rows known as periods.  (ii) 18 vertical columns known as groups.  (iii) 4 blocks Periods There are seven periods in the periodic table. The number of elements in each period corresponds to number of electrons in different major energy levels. Each period starts with a new principle quantum number.  The horizontal rows from left to right in the periodic table are called periods.  There are 7 horizontal rows. So there are 7 periods.  The number of elements in each period corresponds to number of electron in different energy levels.  1 st  PERIOD This period corresponds to first energy level, whose capacity is two electrons. So there are two elements present in the 1st period. They are H(1s 1 ) , He (1s 2 ) . It is the shortest period.  2nd  PERIOD...

It was discovered by Moseley.   It was based on atomic number.  Modern periodic law :-   The physical and chemical properties of elements are periodic function of their atomic number . That is if the elements are arranged in the increasing order of their atomic number . Then the similar properties of element are repeated after a regular intervals, i.e. 2,8,8,18,18,32. Characteristics of modern periodic table  :- Elements are classified according to their atomic number.  Ther periods e are 9 vertical groups and 7 horizontal periods The groups upto VII - 7 groups , VIII - 1group, '0' - 1 group '0' - group elements are called Inert gas or Noble gas group. This group was discovered by Ramsay. 

  PERIODIC TABLE  :- The method of arranging similar elements in one group and separating them from dissimilar elements is called classification of elements.  A table which has been formed by the classification of elements is known as periodic table.  Mendeleev's Periodic Table  :- Mendeleev arranged sixty three elements in a table on the basis of periodic law, which states that physical and chemical properties of the elements are the periodic function of their atomic masses i.e. when elements are arranged in the increasing order of atomic masses similar elements are repeated after regular intervals.  Advantages of Mendeleev's periodic table   (1) Prediction of new element  :- In Mendeleev's periodic table there were many vacant spaces. He had predict the properties of elements that would occupy when discovered. When few elements were later discovered they were found to be similar properties as predicted by Mendeleev.  Ex :-   Eleme...