Chapter 4 Periodic Table of Elements

Question 1

What is the periodic table of elements?

Answer 1

Classifies known chemical elements in a table according to certain characteristics

Question 2

What was Antoine Lavoisier’s contribution to the periodic table

Answer 2

• Classified elements according to certain groups such as gases, non metals, metals and metal oxide
• Less accurate because he classified light, heat and a few compounds as elements
• Several elements were classified into same group but showed different chemical properties

Question 3

What was Johanna W. Dobereiner contribution to the periodic table

Answer 3

• Founded the triad classification, which showed the relationship between the chemical properties of elements and atomic mass
• ie: Bromine, chrorine and Iodine

Question 4

What was John Newlands contribution to the periodic table

Answer 4

• Arranged elements according to their increasing atomic masses
• Law Of Octaves, which arranged seven elements in a row because he found that the chemical and physical properties of the first element recurred at every eighth element

Question 5

What was Lother Meyer’s contirbution to the periodic table

Answer 5

• Plotted the graph of atomic volume against atomic mass of elements
• Found that elements at equivalent positions on the curve of the graph had similar chemical properties
• Proved the recurrence in properties of elements

Question 6

What was Dmitri Mendelev contribution to the periodic table?

Answer 6

• Arranged elements according to their increasing atomic masses
• Only elements with similar chemical properties were arranged int he same vertical columns and left several empty spaces in his periodic table
• He was successful in predicting the properties of undiscovered elements

Question 7

What was Henry Mosely’s contribution to the periodic table?

Answer 7

• Found a relationship between X-ray spectrum and proton numbers
• Proposed that each element ought to have its own proton number
• Arranged each element according to their increasing proton numbers and also left empty spaces in his periodic table`

Question 8

How is the periodic table arranged?

Answer 8

Arranged in the ascending order of proton numbers, ranging from 1 to 118
Elements with the same chemical properties are placed in the same vertical columns

Question 9

What are the vertical columns in the periodic table called?

Answer 9

Groups

Question 10

What are the horizontal rows in the periodic table called? and how many are there?

Answer 10

Periods, 7

Question 11

Why are noble gases chemically unreactive ?

Answer 11

• Valence shells are fully filled with electrons
• Achieved a stable duplet or octet electron arrangement, causing the atoms of noble gases to neither donate, accept nor share electrons with the atoms of other elements

Question 12

What are the changes in physical properties of elements when going down group 18?

Answer 12

• Melting and boiling point of elements of elements increase
• Atomic size of elements with increase which increases the attraction force between the atoms
• Attraction force becomes stronger and more heat energy is required to overcome this force

Question 13

What are group 18 elements?

Answer 13

helium
neon
argon
krypton
xenon
radon

Question 14

Uses of helium

Answer 14

Fill weather balloons
oxygen tank of divers

Question 15

Uses of Neon

Answer 15

Used in advertising broad lights

Question 16

Uses of argon

Answer 16

Fill electric bulbs
Provide an inert atmosphere for welding in high temperatures

Question 17

Uses of krypton

Answer 17

Flashlight of cameras
Lasers for eye retina treatment

Question 18

Uses of xenon

Answer 18

Lighthouse lamps
anesthesia

Question 19

Uses of radon

Answer 19

treat cancer

Question 20

Changes in the chemical properties of elements when going down group 1

Answer 20

• Atomic radius of elements increase
• Atomic size increase which will weaken the attraction force between the atoms. Thus, less heat is required to overcome the attraction force between metal atoms