All chemical and physical properties are a manifestation of the ____ of elements.
All chemical and physical properties are a manifestation of the electronic configuration of elements. The periodic trends in certain fundamental properties such as atomic and ionic radii, ionization enthalpy, electron gain enthalpy and valence are related to electronic configuration.
The nobel gases are unreactive because
The metallic character of the elements ____ down the group.
The metallic character of the elements increases down the group. In a group, the increase in atomic and ionic radii with increase in atomic number generally results in a gradual decrease in ionization enthalpies and a regular decrease (with exception in some third period elements) in electron gain enthalpies, in the case of main group elements. Thus, the metallic character increases down the group and non-metallic character decreases.
If the two members of a Dobereiner triad are phoshorus and antimony,the third member of this triad is --
In the periodic tabe, with the increase in atomic number, the metallic character of an element
Metallic character decreases in a period and increases in a group.
Ionisation energy decreases down the group due to
When we move down the group,atomic size increases, distance bewteen nucleus and valence shell electron increases and ionisation energy decreases.
In the modern periodic table one of the following does not have appropriate positions-
The different types of atomic radii are _____.
The different types of atomic radii are Van der Waals, covalent and metallic radius. Depending upon whether an element is a metal or a non-metal, the different types of atomic radii are used namely Van der Waals radius, covalent radius and metallic radius. In case of non-metals, atomic radius refers to either covalent or Van der Waals radius.
Which form coloured salts?
Most of the transition metal componds (ionic as well as covalent )are coloured both in the solid state and in aqueous solution in contrast to the componds of s and p-block elements due to the presence of incomplete d-subshell.
In the periodic table from left to right in a period the atomic volume.
Atomic volume is the volume occupied by the one gram of an element. Within a period from left to right, atomic volume first decreases and then increaes due to increaes of nuclear charge and increase in the number of electrons in the valence shell.
Which of the following element is not in the liquid state?
The elements with atomic numbers 2, 10, 18, 36, 54 and 86 are all-
Which among the following is most electronegative element and least electronegative element?
The most electronegative element is F and least electronegative element is Cs. The electronegativity increases along a period due to increase in the nuclear charge and decrease in the atomic radius and the electronegativity decreases down the group due to increase in atomic radius which in-turn increases the screening effect. Thus, the most electronegative element is fluorine (F) and the least electronegative element is Caesium (Cs).
Nobel gases were included in Mendeleev's periodic table in the --
The ionic radius of lithium is ____pm.
The ionic radius of lithium is 76 pm. The ionic radii of Be, Na and Mg are 31, 102 and 72 pm respectively.
The elements which are exceptions to the categorisation of periodic table are ____ and ____.
The elements which are exceptions to the categorisation of periodic table are hydrogen and helium. Helium belongs to the s-block but its positioning in the p-block along with other group 18 elements is justified because it has a completely filled valence shell (1s2) and as a result, exhibits properties characteristic of other noble gases. The other exception is hydrogen. It has a lone s-electron and hence can be placed in group 1 (alkali metals). It can also gain an electron to achieve a noble gas arrangement and hence it can behave similar to a group 17 (halogen family)elements. Because it is a special case, hydrogen is placed separately at the top of the Periodic Table.
The electron affinity for the inert gases is --
Newlands could classify elements only upto--
The most significant contribution towards the development of periodic table was made by
The elements present in group 18 are known as ____.
The elements present in group 18 are known as noble gases. Elements present in group 1 & 2 are light metals,elements in groups 3 - 12 are transition metals, and elements from group 13 - 18 are non-metals.
The number of elements in each of the innertransition series is --
In the long form of periodic table, the horizontal rows are called ____ and the vertical columns are called ____.
In the long form of periodic table, the horizontal rows are called periods and the vertical columns are called groups. The groups and periods are also known as families and series respectively.
The distribution of electrons in the orbitals of an atom is called its ____.
The distribution of electrons in the orbitals of an atom is called its electronic configuration.The principal quantum number (n) defines the main energy level known as shell. The filling of electrons into different sub shells, also referred to as orbitals (s, p, d, f ) in an atom.
Which is metalloid--
Mendeleev classified elements in--
According to the periodic Law of elements, the variation in properties of elements is related to their
The properties of elements change with a change in atomic number.
Which of the following sets has strongest tendency to form anions?
N,O and F(p-block elements) are highlyelectronegative non metals andwill have the strongest tendency to form anions by gaining electrons from metal atoms.
The number of elements known at present is ____.
The number of elements known at present is 114. In 1800, only 31 elements were known. By 1865, the number of identified elements had more than doubled to 63. At present 114 elements are known. Of them, the recently discovered elements are man-made. Efforts to synthesis new elements are continuing.
The alkali metals present in group I are ____.
The alkali metals present in group I are Li, Na, K, Rb, Cs & Fr. Be, Mg, Ca, Sr, Ba & Ra are alkaline earth metals present in group II A.
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