Question

salient features of modern periodic table

Answer 1

salient feature of the Modren periodic table are: 1. the periodic table has 18 vertical columns called groups. and seven horizontal rows called periods.

Answer 2

Answer:

HEY THERE!!

Classification

• Periodic table based on basic fundamental property - atomic number.

Position

• Correlates position of an element with its electronic configuration.

Methodical Arrangement

• Arranges elements in increasing order of atomic numbers in 'SEVEN' horizontal rows called 'PERIODS' and 'EIGHTEEN' vertical columns called 'GROUPS'.
• Completion of each period is. logical, since each period begins with an element having one electron in outermost shell and ends with zero group element having completely filled outer shell.
• Each vertical column accommodates elements with the same outer electronic configuration, hence having similar properties.
• '18' vertical columns consists of groups 1 to 17 and 18 [zero group].

- Group 1,2 and 13 to 17 [I A to VII A] are called 'NORMAL ELEMENTS'.

- Groups 3 to 12 [I B to VII B and VIII] are called 'TRANSITION ELEMENTS'.

- Group 18 [zero] at extreme right contains 'NOBLE INERT GASES'.

Separation of elements

• Reactive metals - are placed in group 1 [I A] and 2 [II A].
• Transition elements - [metals] are placed in the middle.
• Non-metals - are placed in the upper right corner of the periodic table.

Periodicity of elements

• Gradual change in properties - is seen with increase in atomic number in the periodic table.
• Periodicity in properties - i.e. recurrence in properties are seen with elements belonging to the same subgroup in the periodic table after a difference of 2,8,18 or 32 in atomic numbers due to recurrence of similar valence shell electronic configuration.