Classification of Elements and Periodicity

Question 1

Drawback of New Zealands’s law of Octaves.

Answer 1

It’s valid upto Calcium only and Noble gases were not discovered at that time.

Question 2

How the elements are taken in Dobereiner triads.?

Answer 2

• Elements from the same group.
• Difference in atomic number is same.
  Li(3) 8 Na(11) 8 K(19)

Question 3

What is Z Effect? What does it mean when Z * increase .

Answer 3

The +ve Charge which reaches the last electron(Test Electron) is called Z Effect. Z * increases means +ve Charge in the nucleus increases.

Question 4

What is Sigma?

Answer 4

Sigma is Screening Constant. It is different for different shells electrons. Closer you are to the nucleus greater is the sigma or Screening constant.

Question 5

If a subshell has lower energy level it’s Penetration Power will be high or low.

Answer 5

High

Question 6

In Case of S and P Block when we move from Left to Right Z* increases in Order of:

Answer 6

0.65 coz 1 Electron is added in the nth shell so sigma increases by 0.35 and hence z* increases by .65 Forget about protons.

Question 7

In case of Copper and Chromium 2 electrons enters into the( n-1) th shell. So, how much sigma contribution has increased.

Answer 7

0.5 ( Actually 1 Electron has to go to nth shell but it has gone to (n-1)th shell.

Question 8

What is the first thing we have to do to calculate the Z* ?

Answer 8

Grouping of Electronic Configuration.

Question 9

What is the another meaning of sigma?

Answer 9

How much +ve charge is stopped in the between.

Question 10

In case of d block when moving from Left to Right Z* increases in order of :

Answer 10

0.15

Question 11

Order of Sigma for s p d f

Answer 11

s > p > d > f ( s is having maximum sigma(Stopping Power) because it is closer to the nucleus).

Question 12

Meaning of sigma discovered by me.

Answer 12

Stopping power.