An element belongs to period 2 and group 2, then number of valence electrons in the atoms of this element is?
The elememt belongs to group 2 and period 2 is Be( atomic number 4). Thus 2 electrons will be accommodated in first and other 2 in next shell(that is ,it is the outer or valence shell). Valence shell contains 2 electrons.
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:
7 N - (1s)2(2s)2(2px)1(2py)1(2pz) and
8 O - (1s)2(2s)2(2px)2(2py)1(2pz)1
The size of isoelectronic species: F–, Ne and Na+ is affected by:
Isoelectronic species are the species belonging to different atoms or ions which have same number of electrons but different magnitudes of nuclear charges.
The size of an isoelectronic species increases with a decrease in the nuclear charge (Z). For example, the order of the increasing nuclear charge of F–, Ne, and Na+ is as follows:
F– < Ne < Na+
Z 9 10 11
Therefore, the order of the increasing size of F–, Ne and Na+ is as follows:
Na+ < Ne < F–
When magnesium burns, in air, compounds of magnesium formed are magnesium oxide and:
When magnesium burns in 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- ions is most unlikely to exist as Be has higher tendency to loose electron and Be has full filled configuration.
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 which 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 dose not reflect the periodicity of the elements
Neutron/proton ratio is cause of radioactivity
If the aufbau principle had not been followed, Ca (Z = 20) would have been placed in the:
Electronic configuration of Ca is 1s22s22p63s23p64s2.
Filling of 3d orbital starts after the filling of 4s orbitals. If the aufbau principle had not been followed, the filling of 3d orbital would have been prior to filling of 4s orbital and the electronic configuration of Ca would have been 1s22s22p63s23p63d2 and it belongs to d block.
What is the atomic number of the element with the maximum number of unpaired 4p electron:
Electronic Configuration, which are 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 Galse (F):
Correct Answer :- d
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.
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 period and group is same it can only be for 2s2, and for 2s2 principle 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:
The further away an electron is from the nucleus, the less force it feels from the electron, so the less energy is needed to “pop it off” the atom. The value of the energy level is exactly this amount of energy so the smaller it is, the smaller the difference with neighboring levels will be.
Which of the following properties of the alkaline earth metals increase from Be to Ba:
(I) Atomic radius
(II) Ionisation energy
(III) Nuclear charge
Effective nuclear charge increases down the group and atomic radii increases due to addition of a new subshell
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:
Na+: 1.02 Ao
Be2+: 0.39 Ao
Mg2+: 0.72 Ao
Li+: 0.76 Ao
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?
F- and Na+ both have 10 electrons .Atomic no of F is 9 and for Na it is 11.so for F-, 9 proton is pulling 10 electrons and for Na+,11 proton is pulling 10 electrons . So attractive force is more for Na+ compared to F-. So radius of F- is more than Na+.
The correct order of ionic size of N3–, Na+, F–, Mg2+ and O2– is:
If the ions derived from different atoms are isoelectronic species, then they all have same number of electrons in their electronic shells and will have got same electronic configuration but their nuclear charge will differ because of their difference in number of protons in the nucleus. With increase in number of protonsin the nucleus the electrons are more attracted towards nucleus thereby causing the decrease in ionic radius. On this principle our problem will be solved
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:
For Mg2+and Al3+ you can just check (z/e) ratio as these two are isoelectronic species, and you must know that, Li+ is slightly greater than Mg2+ ,this is a experimemntal data, the reason is out of your syllabi as it includes Schrodinger's eqⁿ,well K+ has the configuration of Ar which makes it larger among them as noble gases are abnormally larger than their neighbor elements due to extra stability
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:
If any atom loss electron then their radius will be decrease so , it means radius of atom K has more value then K+ ion
and if any atom gain electron then their size increases it means radius of F atom is smaller then F- ion.