PERIODIC TABLE OF ELEMENTS

-NUR ARINA BINTI AHMAD SIDI--13202--413-

-ENCIK HAIRULZAM-

Henry J.G.MOseley

Dmitri Mendeleev

Lothar Meyer

John Newlands

Johann Dobereiner

Antoine Lavoisie

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HISTORY

1789, classify substances including light and

heat, into metals and non metals.

Unsuccessful because light, heat and a few other compounds were also considered as elements.

Antoine Lavoisier

1829, divide the elements into groups of 3

elements with similar chemical properties, known as Dobereiner’s triads.

Atomic mass of the middle elements was approximately the average atomic mass of the other 2 elements in each triad.

There was a relationship between the chemical properties and the atomic mass of each elements.

Johann Dobereiner

1864 – 1865, arrange the known elements in

order of increasing atomic mass. Elements with similar properties recurred at every 8 elements, known as the law of Octaves.

Failure because the Law of Octaves was obeyed by the first 17 elements only.

Show the existence of a periodic pattern for the properties of elements.

John Newlands

1870, plotted a graph of the atomic volume

against of the atomic mass for all the known elements.

Realised that elements with similar chemical properties occupied equivalent positions on the curve.

Show that the properties of the elements formed a periodic pattern against their atomic masses.

Lothar Meyer

1869, arrange the elements in order of

increasing atomic mass and grouped them according to similar chemical properties.

He left gaps in the table to be filled by undiscovered elements.

Able to predict the properties of undiscovered elements.

Dmitri Mendeleev

1949, studied the x-ray spectrum of elements.

Concluded that proton number should be the basis for the periodic change of chemical properties instead of the atomic mass.

Rearranged the elements in order of increasing proton number in the Periodic Table. Thus, confirmed the works of Mendeleev.

Henry J.G. Moseley

Arrange in increasing order of proton number. (ranging

from 1 to 113)

Elements with similar chemical properties are placed in the same vertical column.• Each vertical column of elements is called a group. (Group 1

to Group 18)• Horizontal row of elements in the table is called Period

The Group and Period of an element can be known by the electron arrangement :• Number of valance electron : Position of the group• Number of shells : Position of period

ARRANGEMENT OF ELEMENTS

X

13

electron arrangement : 2.8.3 Group : Group 13 and Period : 3

example :

PERIODIC TABLE

Q & A (objective questions)

Who is the scientist that classify the elements with the same chemical properties into a groups called triads ??

A. Dmitri MendeleevB. John NewlandsC. Antoine LavoisierD. Johann Dobereiner

answer: D

Question 1

Who was the scientist that left gaps in the periodic table for elements which were not known at that time ??

A. John NewlandsB. Dmitri Mendeleev

C. Lothar MeyerD. Henry J.G Moseley

answer: B

Question 2

In the periodic table, S is below T in the same group. If the proton number of T is 12, what is the electron arrangement of S ??

A. 2.2B. 2.8.3C. 2.8.8.2D. 2.8.8.4

answer: c

Question 3

Textbook Chemistry Form 4

http://www.slideshare.net/faridahhamat/chapter-4-perodic-table

REFERENCE

special thanks to all

Chemistry TEACHERS !!!

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