Question

if a fireman of 40 kg slips on a pole where frictional force is 320 newton what is the acceleration of fireman​

Answer 1

Answer:

Modern periodic table : long form of the periodic table

The classification of elements resulting from an arrangement of the elements in an

increasing order of their atomic numbers is the modern periodic table. The properties of

elements can be predicted more accurately with the help of the modern periodic table

formed on the basis of atomic numbers. The modern periodic table is also called the long

form of the periodic table.

In the modern periodic table the elements are arranged in accordance with their atomic

number. (see table 2.7) As a result, most of the drawbacks of Mendeleev’s periodic table

appear to be removed. However, the ambiguity about the position of hydrogen is not

removed even in the modern periodic table.

We have seen in the previous

standard that the electronic configuration

of an atom, the way in which the electron

are distributed in the shells around the

nucleus, is determined by the total

number of electrons in it; and the total

number of electrons in an atom is same

as the atomic number. The relation

between the atomic number of an element

and its electronic configuration is clearly

seen in the modern periodic table.

Structure of the Modern Periodic Table

The modern periodic table contains

seven horizontal rows called the periods

1 to 7. Similarly, the eighteen vertical

columns in this table are the groups 1 to

18. The arrangement of the periods and

groups results into formation of boxes.

Atomic numbers are serially indicated in

the upper part of these boxes. Each box

corresponds to the place for one element.

Apart from these seven rows, two rows are shown separately at the bottom of the

periodic table. These are called lanthanide series and actinide series, respectively. There

are 118 boxes in the periodic table including the two series. It means that there are 118

places for elements in the modern periodic table. Very recently formation of a few elements

was established experimentally and thereby the modern periodic table is now completely

filled. All the 118 elements are now discovered.

The entire periodic table is divided into four blocks,viz, s-block, p-block, d-block and

f-block. The s-block contains the groups 1 and 2. The groups 13 to 18 constitute the p-block.

The groups 3 to 12 constitute the d-block, while the lanthanide and actinide series at the

bottom form the f-block. The d-block elements are called transition elements. A zig-zag

line can be drawn in the p-block of the periodic table. The three traditional types of

elements can be clearly shown in the modern periodic table with the help of this zig-zag

line. The metalloid elements lie along the border of this zig-zag line. All the metals lie on

1. the left side of the zig-zag line while all the nonmetals lie on the right side.