SCHOOL OF ELEMENTS STANDARD X SCIENCE AND TECHNOLOGY FIRST CHAPTER

FILL IN THE BLANKS

Fill in the blanks :
1. The horizontal rows in the periodic table are ................ .
2. From left to right, the atomic size of an atom................. .
3. There are ............... periods in the periodic table.
4. An element is placed in group II A, so the number of valence electrons is  ..............
5. An element is placed in 2nd period, so it has ....................... shells.
6. Noble gases have valency as ....................... 7. Metals have a tendency to ....................... electrons..
8. Valency across a period ....................... .
9. Valency down the group ....................... .
10. Elements of group I A and II A are ....................... .
11. An atom is said to be a non-metal if it .................... electrons.
12. ....................... is the only element in duplet state.
13. The electronic configuration of Neon is ....................... .
14. Sodium is a ....................... .
15. Silicon and antimony are ....................... .
16. Group 1A is called ....................... .
17. Group II A is called as ....................... .
18. Group VII A is called as ....................... .
19. The chemical properties down the group ................... .
20. First period contains .................. elements.
21. Moseley arranged elements according to .................. .
22. The non-metals are present in.............. .
23. The number of shells down the group ....................... .
24. The transition character of elements is from……… to .............. .
*25. The formula of chloride of metal is MCl2 , the metal M belongs to ....................... group.
*26. ....................... group contains all gases at room temperature.
*27. The arrangement of elements in a group of three is called ....................... .
*28. The law used by Newlands to arrange elements is called ....................... .
*29. Elements showing properties of both metals and non-metals are called as................
*30. The element eka-Aluminium is called as ....................... .


ANSWERS


A.    Answers.
1.     Periods
2.     Decreases
3.     7
4.     2
5.     2
6.     0
7.     Donate
8.     Varies gradually
9.     Remains the same
10.  Metals
11.  Gains or shares
12.  Helium
13.  2,8
14.  Metal
15.  Metalloids
16.  Alkali metals
17.  Alkaline earth metals
18.  Halogens
19.  Remain the same
20.  2
21.  Atomic number
22.  Upper right hand corner
23.  Increases
24.  Metallic to non – metallic
25.  IIA
26.  18 or zero
27.  Triad
28.  Newlands Law of octaves
29.  Metalloids
30.  Gallium


Matchthecolumns.


Column I
Column II
1.       Sodium
2.       Cerium
3.       Sulphur
4.       Manganese

a.       Lanthanide
b.       Metalloid
c.        Transition metal
d.       Noble metal
e.        Metal
f.        Non – metal.
.

Ans: -Column I
Column II
1.       Sodium
2.       Cerium
3.       Sulphur
4.       Manganese

e. Metal
a. Lanthanide
f. Non – metal
b. Metalloid


















GIVE SCIENTIFIC REASONS [Textual]

Atomic size increases down the group


Metallic character decreases from left to right in a period


Elements in the same group show the same valency




GIVE SCIENTIFIC REASONS [Non Textual]

Chlorine is placed in VII A group in the modern periodic table.

Metallic character decreases across a period.

Group VII A elements are strong non-metals and group I A elements are strong metals.

Non-metallic character increases across a period.

Atomic size decreases across a period.

The family of noble gases is called as zero group.

Valency varies gradually across a period.



ANSWER THE FOLLOWING


How could the modern periodic table remove various anomalies of Mendeleev's periodic table?


In modern periodic table, which are the metals, non metals and metalloids among the first 20 elements?


What are the demerits of Mendeleev's Periodic table?


Define atomic size. How does it vary in a period and in a group?


Name three elements


The atomic number of an element X is 17. Predict :



Read the following descriptions and decide whether the element belongs to metal or non-metal. Justify your answer.


How do you calculate valency of an element from its electronic configuration ?


What should be the position of Hydrogen in the Modern Periodic Table ? Why?



How are isotopes of different elements placed in the Modern Periodic Table ?



Why is atomic number said to be a fundamental property?


Explain the features of Mendeleev's periodic table.


Explain the zig-zag line in the periodic table.

QUESTION PAPERS


  

  
CH. NO. 1 SCHOOL OF ELEMENTS

  
  

  

CH. NO. 4 ELECTRIC SPARK

  
CH. NO. 5 ELECTROMAGNETISM

  

  

  

  

  

  
CH. NO. 11 REGULATORS OF LIFE

  
CH. NO. 12 LIFE CYCLE

  
CH. NO. 13 MAPPING OUR GENES