What are Zeeman and Stark effects? Were they explained by the Bohr’s theory?

The splitting of spectral lines into many components in the presence of a magnetic field is called Zeeman effect.

Analogously, the splitting of spectral lines into many components in the presence of an electric field is called Stark effect. 

These effects could not be explained within the framework of Bohr's theory and required the presence of multiple non-circular orbits corresponding to each energy level. An effort, with some degree of success, was made by Sommerfeld to explain these phenomena by invoking multiple elliptical orbits corresponding to each energy level. The Bohr Sommerfeld theory was ultimately discarded along with Bohr's model for other reasons.

Ionization energy of Boron is smaller than Beryllium even though effective nuclear charge is higher?

The electronic configurations of Boron and Beryllium are (₅B=1S²,2S²,2p¹) and (₄Be =1S²,2S²).

In Boron the outermost electron is present in the 2p orbital (low penetration power) and is less strongly bound than the electron present in a 2S orbital of Beryllium (Have more penetration power), which will has a higher Zeff. It is easier to ionize the Boron atom.

Related Questions:

(1) What are the Amphoteric metals ? gives Examples.

(2) Name of total metalloids present in periodic table ?

(3) Total numbers of elements which are liquid at normal temperature is ?

(4) What is Mendeleev's periodic table ? give important features and draw back of Mendeleev's table.

(5) What is atomic density ? give the periodicity of atomic density in periods and groups.

(6) What is atomic volume ? and what is periodicity of atomic volume in groups and periods ?

(7) Why there are 2, 8 and 8 elements in first, second and third periodic of periods table respectively ? Explain.

(8) In alkali metal group which is the strongest reducing agent in aqueous solution and why?

(9) The electron affinity of sulphur is greater than oxygen. Why?

(10) The first ionization energy of carbon atom is greater than that of boron atom, whereas reverse is true for the second ionization energy. Explain.

(11) The electronegativities of B, Al, Ga are 2.0, 1.5, 1.6 respectively. The trend is not regular. Explain.

(12) Li2CO3 decomposes on heating but other alkali metal carbonates don’t. Explain.

(13) Of all noble metals, gold has got a relatively high electron affinity. Explain.

(14) What are the increasing order of ioni radii of first group elements in water ?

(15) What are the increasing order of molar conductivity of first group elements in water ?

 

The complex formation Tendency of NH3 is wisher than PH3.

SOLUTION: In NH₃ lane pair is present in one of the sp³ Hybridized orbital. While in PH₃ lone pair is present in pure S orbital and hence lane pair donation capacity of NH₃ is stronger than PH₃

What happens if two deactivating and one activating group is present on a benzene ring?

We know that reactivity of benzene ring towards electrophilic reaction depends upon presence of group on benzene ring. Benzene gives electrophilic substitution reaction due to negative pi cloud formation , if there is EWG (electron withdrawing) group on benzene ring it's negativeness decreases and reactivity also decreases and due to resonance upcoming group goes at meta position only while in the presence of ERG (electron releasing groups) it's negative ness increases and reactivity increase and due to resonance upcoming group goes at ortho and para position .

If both EWG and ERG present on benzene ring then upcoming electrophile goes to ortho and para position  according to ERG group .

What is bromoform reaction?

Haloform reaction includes Chloroform, Bromoform and Iodoform reaction, It is feature reaction of terminal methyl ketones and alpha hydroxy ketones . In which methyl ketones oxidised in the presence of I2 and NaOH ( NaOI) into Sodium salt of carboxylic acid and corresponding haloform ( Chloroform , Bromoform and Iodoform)