Classification of Elements

Question 1

Size of an atom

Answer 1

1.2 A°

Question 2

Basic unit of all matter

Answer 2

Elements

Question 3

In 1800, only ____ elements were known

Answer 3

31

Question 4

By 1865 ____ elements were discovered.

Answer 4

More than 63

Question 5

At present ___ elements are known

Answer 5

118

Question 6

Why do we need to classify elements

Answer 6

•There are a huge number of elements discovered and yet to be discovered.
•To rationalize the known chemical facts about elements.
•Predict new elements along with their properties to further the studies.

Question 7

The German chemist,_____ in
early 1800’s was the first to consider the idea
of trends among properties of elements.

Answer 7

Johann Dobereiner

Question 8

Law of triads was proposed in the year

Answer 8

1829

Question 9

Who,in which year arranged the then known elements in order of
increasing atomic weights and made a
cylindrical table of elements to display the
periodic recurrence of properties?

Answer 9

French geologist,
AEB de Chancourtoise in 1862.

Question 10

Who,in which year proposed law of octaves?

Answer 10

The French chemist,John Alexander Newlands in 1865.

Question 11

Which classification resembles the pattern of musical notes?

Answer 11

Law of octaves (1865)

Question 12

Newlands law of octaves was true for only elements upto _____.

Answer 12

Calcium

Question 13

What was awarded to Newlands for his work of Law of Octaves?

Answer 13

He was awarded
Davy Medal in 1887 by the Royal Society,
London

Question 14

The Periodic Law, as we know it today owes
its development to ____ and ____.

Answer 14

Russian chemist, Dmitri
Mendeleev (1834-1907) and the German
chemist, Lothar Meyer (1830-1895)

Question 15

Lothar Meyer
plotted the physical properties such as atomic
volume, melting point and boiling point
against atomic weight and obtained a
periodically repeated pattern. Unlike
Newlands, Lothar Meyer observed

Answer 15

A change in length of the repeating pattern

Question 16

By the year ____ Lothar Meyer had developed a table of the elements that closely resembles the modern periodic table.

Answer 16

1868

Question 17

Medeleeves periodic law states

Answer 17

The properties of the elements are a
periodic function of their atomic
weights.

Question 18

The two aspects Mendeleev relied on, while making the periodic table.

Answer 18

•the similarities in the empirical formulas
•properties of the compounds formed by the
elements.

Question 19

Site an example for Mendeleev not following his own periodic law.

Answer 19

iodine with lower atomic weight
than that of tellurium (Group VI) was placed
in Group VII along with fluorine, chlorine,
bromine because of similarities in properties

Question 20

What is Eka Aluminum

Answer 20

Gallium

Question 21

What is Eka Silicon

Answer 21

Germanium

Question 22

Mendeleeves periodic table was published in the year

Answer 22

1905

Question 23

How did Henry Moseley show that the atomic number is a more fundamental
property of an element than its atomic mass?

Answer 23

In 1913, the
English physicist, Henry Moseley observed
regularities in the characteristic X-ray spectra
of the elements. A plot of ν (whereν is
frequency of X-rays emitted) against atomic
number (Z ) gave a straight line and not the
plot of ν vs atomic mass.

Question 24

Modern periodic law states

Answer 24

The physical and chemical properties
of the elements are periodic functions
of their atomic numbers.

Question 25

Ore of uranium

Answer 25

Pitch Blende

Question 26

Pitch Blende contains

Answer 26

Neptunium
Plutonium
Actinium
Protactinium

Question 27

The Periodic Law revealed important
analogies among the ___ naturally occurring
elements

Answer 27

94

Question 28

Assertion : A renewed interest was stimulated
in Inorganic Chemistry and
carried into the present with the creation
of artificially produced short-lived elements.

Reason :The Periodic Law revealed important
analogies among the 94 naturally occurring
elements (neptunium and plutonium like
actinium and protoactinium are also found in
pitch blende – an ore of uranium

Answer 28

Both A and R are correct and Reason is the correct explanation of the assertion.

Question 29

Most convenient and widely used form of periodic table is

Answer 29

The long form of periodic table.

Question 30

Horizontal rows in Mendeleeve’s periodic table is called

Answer 30

Series

Question 31

Horizontal rows in long form of periodic table are alled

Answer 31

Periods

Question 32

Elements having similar outer electronic configuration is arranged as

Answer 32

Vertical columns called groups/families.

Question 33

Expand IUPAC

Answer 33

International Union of Pure and Applied Chemistry

Question 34

How many periods and groups are there in the long form of the periodic table?

Answer 34

7 periods and 18 groups.

Question 35

What does the period number represent?

Answer 35

The highest principal quantum number.

Question 36

No of elements in the 7 periods?

Answer 36

2
8
8
18
18
32

Seventh period - Incomplete
Theoretical maximum 32

Question 37

The 14 elements of sixth period is separately placed at the bottom and are called

Answer 37

Lanthanoids

Question 38

The 14 elements of seventh period is separately placed at the bottom and are called

Answer 38

Actinoids

Question 39

Elements after 100.

Answer 39

101 - Mendeleevium
102- Nobelium
103 - Lawrencium
104 - Rutherfordium
105 - Dubnium
106 - Seaborgium
107- Bohrium
108 - Hassium
109 - Meitnerium
110 -Darmstadtium
111 - Roentgenium
112 - Coppernicium
113 - Nihonium
114 - Flerovium
115 - Moscovium
116 -Livermorium
117 -Tenassine
118 -Oganesson

Question 40

Temporary name of element with atomic number 103

Answer 40

Unt

Question 41

Permanent name of 104

Answer 41

Rutherfordium

Question 42

Permanent name represent

Answer 42

The country or state of country where the element was discovered
Or Pay tribute to a notable scientist.