An element belongs to period 2 and group 2, then the number of valence electrons in the atoms of this element is:
Anything that influences the valence electrons will affect the chemistry of the element. Which one of the following does not affect the valence shell?
Nuclear mass does not affect the valence electrons because the nuclear mass is so small, it is considered as negligible.
The first ionization potential in electron volts of nitrogen and oxygen atoms are respectively given by:
Nitrogen has higher ionization energy than Oxygen because it has a stable half-filled electronic configuration as shown below:
N - (1s)2(2s)2(2px)1(2py)1(2pz)1
O - (1s)2(2s)2(2px)2(2py)1(2pz)1
The size of isoelectronic species, F–, Ne and Na+ is affected by:
When magnesium burns, in the air, compounds of magnesium formed are magnesium oxide and ______.
When magnesium burns in the air it forms magnesium nitride with nitrogen and with oxygen it forms magnesium oxide.
Which of the following ions is most unlikely to exist?
Be- ion is most unlikely to exist as Be has a higher tendency to lose an electron and Be has a full filled configuration.
Li- = 1s2, 2s2 (In it all sub shells are saturated so, it is stable)
Be- = 1s2, 2s2 2p1
B- = 1s2, 2s2 2p2
C- = 1s2, 2s2 2p3
A, B and C are hydroxy-compounds of the elements X, Y and Z respectively. X, Y and Z are in the same period of the periodic table. A gives an aqueous solution of pH less than seven. B reacts with both strong acids alkalis. C gives an aqueous solution that is strongly alkaline.
Which of the following statements is/are true?
(I) The three elements are metals.
(II) The electronegativities decrease from X to Y to Z.
(III) The atomic radius decreases in the order X, Y and Z.
(IV) X, Y and Z could be phosphorus aluminium and sodium respectively.
Which of these does not reflect the periodicity of the elements?
The neutron/proton ratio is the cause of radioactivity.
If the Aufbau principle had not been followed, Ca (Z = 20) would have been placed in the:
What is the atomic number of the element with the maximum number of unpaired 4p electron?
The electronic configuration is given as follows:
Observation of the above given 4 E.C. tells us that the element having atomic number 33 will have the maximum number of unpaired electrons i.e. 3.
The electronic configuration of four elements are:
Consider the following statements:
(i) I shows variable oxidation state.
(ii) II is a d-block element.
(iii) The compound formed between I and III is covalent.
(iv) IV shows single oxidation state.
Which statement is True(T) or False (F)?
Explanation: (I) [Kr]5s1, shows only single oxidation state +1.
(II) [Rn]5f14 6d1 7s2, it is f-block element (Z=103).
(III) The compound formed between I and Ill is ionic.
(IV) [Ar]3d6 4s2, (Z=26) Fe shows variable oxidation state.
Therefore, all the above statements in the question are false.
If period number and group number of any representative element(s) are same then which of the following statement is incorrect regarding such type element(s) in their ground state: (Period number and group number are according to modern form of periodic table)
When the period and group is the same, it can only be for Hydrogen(1s1) and Beryllium(1s2 2s2). Then:
Principal quantum number (n) = 2,
Azimuthal quantum number (l) = 0,
Magnetic quantum number (m) = 0,
Spin quantum number (s) = +1 / 2 or -1 / 2.
How does the energy gap between successive energy levels in an atom vary from low to high values?
Which of the following properties of the alkaline earth metals increase from Be to Ba:
(I) Atomic radius
(II) Ionisation energy
(III) Nuclear charge
True increasing order of acidity of the oxides of Mn is:
With increasing (+)ve oxidation state, acidity increases.
The set representing the correct order of ionic radius is:
In general, the ionic radius increases on moving from top to bottom in the group and decreases on moving from left to right in a period.
The ionic radius of the following elements are:
Na+: 1.02 Ao
Be2+: 0.39 Ao
Mg2+: 0.72 Ao
Li+: 0.76 Ao
So, the correct option is B.
In which of the following pair, both the species are isoelectronic but the first one is large in size than the second?
The correct order of ionic size of N3–, Na+, F–, Mg2+ and O2– is:
The given ions are:
Hence the increasing order of ionic radius is:
12Mg2+< 11Na+< 9F-< 8O2-< 7N3-
For isoelectronic species, lower the nuclear charge higher the radius.
The order of increasing ionic radius of the following is:
If the ionic radii of K+ and F– are nearly the same (i.,e. 1.34 Å), then the atomic radii of K and F respectively are: