Question

1. What do Quanmum numbers indicate and where do they come from? 2. The principal Quantum number n represents what level of atomic structure and how many electrons are in n=3? 3. What do the orbitals represent? 4. Why is the periodic chart is organized according to Classic Chemical reactivity and orbital structure? 5. Why does Electronegativity increase from left to right and top to bottom? What is the electron configuration of Oxygen and what are the Quantum Numbers for all 8 electrons? 152, 252, 2p4 1s 2s 2p u se arrows to indicate an electron first second 7. What governs the order of Quantum Numbers for # 5-8?

Answer 1

1.quantum numbers indicate basically the energy level of electrons in atom. There are four quantum numbers

First one is Principal Quantum Number : It is denoted by 'n'. This quantum number indicates the distance between electron and nucleus. Increasing the distance from nucleus the value of 'n' increases. In one principal energy level 2n2 electron can stay. This also indicates the size of the atom

Second one is Azimuthal quantum number: It is denoted by 'l'. In 'n' principal energy level n-1 azimuthal number can exist. Basically this quantum number indicates the shape of the orbital. For l = 0 the orbital is 's'

l = 1 the orbital is p

l = 2 the orbital is d

and for 3,4,5 it is f,g,h

Third one is Magnetic quantum number : It is denoted by 'm'. In 'l' azimuthal quantum number the number of magnetic quantum number is 2l+1. For l the m values are from -l to +l. Like for l = 1. the possible m values are -1,0,+1. This quantum number basically indicates the orientation of orbitals in 3d space.

Fourth is spin quantum number : It is theoratically stated that electron has two possible spin - up spin and down spin. So this is denoted by 's'. The two possible values are either +(1/2) or -(1/2).

So basically four quantum numbers are designation of a single electron which means no two two electrons have same four quantum number value. As the quantum numbers are different so the corresponding energies are also different. This difference can be spectroscopically observed.

The quantum numbers are nothing but solution of Schrodinger Wave equation. By solving this equation the quantum numbers came.

2. n represents the primary level of atomic structure. It is principal level of wave model of atom simmiler the atomic radius in Bohr's Model. It indicates the size and radius of atom.

The number of electrons in n orbital is 2n2.

So n = 3, the total nmber of electrons can stay is = 2*32 = 18

3. Orbital is nothing but the solution of the Schrodinger wave equation for one electron system.

For representing easily the orbital is the space in atom where the electron density is maximum.

Basically in particle model or Bohr model of atom, electrons are considered as particle so it is mentioned the exact position of electrons which violates the Heisenberg Uncertainity Principal. So in wave model instead of a particular location scientists assumed a 3d space where the electron cloud can stay that means the highest density of electrons which is called orbitals.

Now orbitals are many types like s,p,d...etc.

SO in one sentence orbital represents the maximum electron density in atomic space.

4. The thought of making periodic table is based on the motive to generelise the the atoms on the basis of their similar reaction property as well structural similarity. In every group is arranged in such way that any atom from any group can represent the whole group. To know about basic chemistry of any group in periodic table one member is enough like group 15 all shows Lewis basicity. Every group follows the basic trend of oxidation of each member that is why the oxidation numbers are almost similar among the groups.

5.Electronegativity is the tendency of atom to attracts the electron density in shared or covalent bonding. So the electronegativity depends on the charge of the nucleus. the positive charge in the nucleus makes the atom more electronegative as it more prones to attract electron pair. From going left to right the charge density of nucleus increases and as a consequence the size decreases so it is more feasible to attract paired electrons. Hence the electronegativity increases from left to right.

Down the group inspite of increasing charge in necleus the electronegativity decreases as the new pricipal energy state introduces leads to increase the size of the atom, so now it is difficult to attract paired electrons for nucleus. So going down the group electronegativity decreases.

6. [o] - 1s 2s%204 15 252 Imlelmis 312 oro 12 2010-12 T +1 -1/2 7. From 5 to 8 , the electrone are filling to p sub Shell where the azimuthal (l, quantum mumber is 1.. As well as 3 possible magnetic quantum mumbers (m) are present which directs the direction of orbital.