The periodic table is an arrangement of the chemical elements based on their properties. Elements are organized by atomic number and similar properties repeat periodically. The periodic table has evolved over time as scientists like Dobereiner, Newlands, Mendeleev, and Moseley discovered patterns in elements and used these patterns to organize the elements. The modern periodic table is a visual representation of the periodic law, which states that properties of elements are periodic functions of their atomic numbers. It provides information about each element's atomic number, atomic mass, electron configuration, and chemical properties.
19. He based his classification of elements on the fact that similar
properties could be noted for every eight element when they are
arranged in order of increasing atomic masses.
20. The Periodic Table of Elements is the visual
representation of the Periodic Law.
21. Periodic Law states that “ If elements are arranged
according to their atomic mass, it shows regular variation.
26. Later, in 1914,
Henry Moseley, an
English Physicist
observed that the
order of the x-
ray frequencies
emitted by
elements follows
the ordering of
the elements by
atomic number.
50. The horizontal rows of the Modern Periodic Table are
called periods. They are numbered from top to
bottom. There are 7 horizontal periods in the
Periodic Table.
56. Elements from the taller columns (groups 1, 2, and
13 through 18) are called the representative
elements or main groups of the periodic table.
Representative elements or main groups
61. Nonmetals are confined to
the right side of the table.
Metalloids have the
appearance and some
properties of a metal but
behave like a nonmetal in
certain instances.
HAVE YOU EVER EXPERIENCE… TRAVELLING TO A NEW PLACE… FOR THE FIRST TIME?
HOW DID YOU ABLE TO LOCATE… THAT CERTAIN PLACE… WHEN YOU STILL HAVE NO IDEA… WHERE IT IS?
DID YOU USE A ROAD MAP, GPS OR YOU JUST READ SIGNAGE ALONG THE WAY?
WHATEVER IT IS… IT’S SURELY USEFUL IF THINGS ARE ALL ORGANIZED.
YOU CAN GET INFORMATION EASILY IF THINGS ARE ORDERLY ARRANGED AND PROPERLY LABELED
SCIENTIST HAVE ALWAYS SEARCHED FOR PATTERNS,
REGULARITIES AND SYMMETRIES IN NATURE…
IF A PATTERN CAN BE DISCOVERED..
INFORMATION AND DATA CAN BE ARRANGED AND ORGANIZED IN WAYS THAT WILL MAKE IT MORE UNDERSTANDABLE, MEANINGFUL, AND USEFUL.
AN EXCELLENT EXAMPLE OF THIS IS THE PERIODIC TABLE OF ELEMENTS.
AT THE END OF THIS LESSON, WE WILL BE ABLE TO ANSWER THE FOLLOWING QUESTIONS.
YOU WILL RECOGNIZE THIS INCREDIBLE FEATURE OF THE PERIODIC TABLE IN THIS MODULE AS YOU EXPLORE
THE FULL POTENTIAL AS A SOURCE OF INFORMATION ABOUT THE ELEMENTS.
THE PERIODIC TABLE OF ELEMENTS….
IS AN ARRANGEMENT OF ELEMENTS…
BASED ON SPECIFIC CHARACTERISTICS AND PROPERTIES.
BEING ORGANIZED ACCORDING TO ATOMIC MASS
ELECTRON
NUMBER
ELECTRON
CONFIGURATION
AND THEIR UNIQUE CHEMICAL PROPERTIES, IN WHICH…THE SCIENTIST CAN EASILY RECOGNIZE THE INDIVIDUAL ELEMENTS.
HERE ARE SOME ESSENTIAL DETAILS
ABOUT THE DEVELOPMENT OF THE PERIODIC TABLE.
THE DEVELOPMENT COULD BE TRACED BACK IN 1817 TO THE WORK OF JOHANN
DOBEREINER
A GERMAN CHEMIST WHO FORMED THE TRIADS OF ELEMENTS WITH SIMILAR PROPERTIES….
LIKE THE TRIAD OF CALCIUM, BARIUM AND STRONTIUM
IN 1863, JOHN NEWLANDS, AN ENGLISH CHEMIST PROPOSED THE LAW OF OCTAVES.
THE PERIODIC TABLE OF ELEMENTS…
IS THE VISUAL REPRESENTATION OF THE PERIODIC LAW.
PERIODIC LAW STATES THAT….
“ IF ELEMENTS ARE ARRANGED ACCORDING TO THEIR ATOMIC MASS…
IT SHOWS REGULAR VARIATION.
IT WAS DISCOVERED BY DMITRI MENDELEEV AND LOTHAR MEYER AROUND 1869.
BOTH FOUND WAYS OF ARRANGING ELEMENTS…
IN ORDER OF INCREASING ATOMIC MASS,
IT IS INTRESTING TO NOTE, THAT THESE TWO SCIENTISTS DID NOT KNOW EACH OTHER,
YET… THEY CAME UP WITH THE SAME CONCLUSIONS.
BOTH SCIENTISTS WERE TEACHERS LIVING AND WORKING IN DIFFERENT PLACES.
MEYER LIVED AND WORKED IN GERMANY
WHILE MENDELEEV IN RUSSIA
BOTH OF THEM ALSO LEFT BLANK SPACES IN THEIR TABLES,
BELIEVING THAT THESE SPACES… WOULD BE FILLED LATER WITH ELEMENTS …YET TO BE DISCOVERED.
LATER, IN 1914, HENRY MOSELEY, AN ENGLISH PHYSICIST
OBSERVED THAT THE ORDER OF THE X-RAY FREQUENCIES…EMITTED BY ELEMENTS.. FOLLOWS THE ORDERING OF THE ELEMENTS BY ATOMIC NUMBER
ATOMIC NUMBER IS EQUAL TO THE NUMBER OF PROTONS IN THE NUCLEUS OF AN ATOM.
THE ATOMIC NUMBER
IS A COMMON CHARACTERISTIC OF ALL ATOMS
OF AN ELEMENT.
NOWADAYS, ELEMENTS ARE ARRANGED ACCORDING TO INCREASING ATOMIC NUMBER.
THE PERIODIC TABLE CONSISTS OF 118 ELEMENTS AND IS REPRESENTED BY SYMBOLS.
THE SYMBOLS OF ELEMENTS ARE BASE ON THE FIRST LETTER OF THE ELEMENT`S NAME
OR THE FIRST TWO LETTERS OF IT.
THE FIRST LETTER OF THE SYMBOL WILL BE CAPITALIZED,
WHILE THE SECOND LETTER,
WRITTEN BY
A SMALL LETTER.
FOR EXAMPLE, THE SYMBOL FOR COPPER IS Cu.
IT STANDS FOR CUPRUM, WHICH IS THE LATIN WORD FOR COPPER.
THE NUMBER ABOVE EACH SYMBOL IN THE TABLE..,
IS ITS UNIQUE ATOMIC NUMBER.
AND THE LOWER NUMBER WITH A DECIMAL POINT…
REPRESENTS THE ATOMIC MASS OF THE ELEMENT.
ELEMENTS ARE ARRANGED IN SUCH A WAY THAT …
INFORMATION ABOUT THE ELEMENTS AND THEIR COMPOUND…
ARE EASILY REVEALED.
THE VERTICAL COLUMNS OF THE MODERN PERIODIC TABLE ARE CALLED GROUPS, AS THEY ARE IN MEMNDEEV’S TABLE.
HOWEVER…
THE MODERN PERIODIC TABLE HAS MANY MORE GROUPS WITH 18…
COMPARED WITH JUST 8 …
IN MENDELEEV’S TABLE.
GROUPS…IDENTIFY THE PRINCIPAL FAMILIES OF ELEMENTS…
AND EACH GROUP HAVE SPECIAL NAMES.
GROUP 1 IS NAMED AS THE ALKALI METALS,
GROUP 2 AS THE ALKALINE EARTH METALS,
GROUP 17 AS THE HALOGENS
GROUP 18 AS THE NOBLE GASES.
GROUPS 13 TO 16 ARE NAMED BASED ON THE FIRST ELEMENT… FOUND IN THEIR FAMILIES.
THUS… GROUP 13 IS CALLED THE BORON
GROUP
THUS… GROUP 14 IS CALLED THE CARBON
GROUP
THUS… GROUP 15 IS CALLED THE NITROGEN
GROUP
THUS… GROUP 16 IS CALLED THE OXYGEN
GROUP. ELEMENTS IN THE SAME GROUP HAVE SIMILAR PROPERTIES. FOR EXAMPLE, ALL ELEMENTS IN GROUP 18 ARE COLORLESS, ODORLESS GASES, SUCH AS NEON (Ne). IN CONTRAST, ALL ELEMENTS IN GROUP 1 ARE VERY REACTIVE SOLIDS.
THEY REACT EXPLOSIVELY WITH WATER
ELEMENTS IN THE SAME GROUP HAVE SIMILAR PROPERTIES. FOR EXAMPLE, ALL ELEMENTS IN GROUP 18 ARE COLORLESS, ODORLESS GASES, SUCH AS NEON (Ne).
IN CONTRAST, ALL ELEMENTS IN GROUP 1 ARE VERY REACTIVE SOLIDS.
THEY REACT EXPLOSIVELY WITH WATER
THE HORIZONTAL ROWS OF THE MODERN PERIODIC TABLE ARE CALLED PERIODS.THEY ARE NUMBERED FROM TOP TO BOTTOM.
THERE ARE 7 HORIZONTAL PERIODS IN THE PERIODIC TABLE.
SOME PERIODS IN THE MODERN PERIODIC TABLE ARE LONGER THAN OTHERS. FOR EXAMPLE, PERIOD 1 CONTAINS ONLY TWO ELEMENTS: HYDROGEN (H) AND HELIUM (He).
IN CONTRAST, PERIODS
6 AND 7 ARE SO LONG THAT MANY OF THEIR ELEMENTS STARTING WITH LANTHANUM (La) IN PERIOD 6 AND ACTINIUM IN PERIOD 7.
THE ELEMENTS ARE GROUPED INTO BLOCKS OR SERIES IN THE PERIODIC TABLE.
GROUP 3 TO 12 CONSTITUTES ONE BLOCK WHEREIN ELEMENTS IN THIS BLOCK ARE REFERRED AS THE TRANSITION ELEMENTS
LANTHANIDES AND ACTINIDES ARE SPECIAL SERIES OF ELEMENTS BUT ALSO PART OF THE TRANSITION BLOCK.
THEY ARE ALSO CALLED THE INNER TRANSITION ELEMENTS.
ELEMENTS FROM THE TALLER COLUMNS (GROUPS 1, 2, AND 13 THROUGH 18) ARE CALLED THE REPRESENTATIVE ELEMENTS OR MAIN GROUPS OF THE PERIODIC TABLE.
WE CAN USE THE PERIODIC TABLE TO IDENTIFY THE KNOWN ELEMENTS AS METALS,
NONMETALS
AND METALLOIDS.
THE NON METALS ARE CONFINED TO THE RIGHT SIDE OF THE TABLE.
THE ELEMENTS ALONG THE STAIR STEP LINE ARE THE METALLOIDS. METALLOIDS HAVE THE APPEARANCE AND SOME PROPERTIES OF A METAL BUT BEHAVE LIKE A NONMETAL IN CERTAIN INSTANCES.
IN THE PRIODIC TABLE ABOVE, ELEMENTS ARE COLOR CODED TO SHOW THEIR CLASS.
AS YOU MOVE FROM LEFT TO RIGHT ACROSS EACH PERIOD OF THE TABLE, THE ELEMENTS CHANGE FROM METALS TO METALLOIDS TO NONMETALS.
THIS ARRANGEMENT ALLOWS US TO STUDY SYSTEMATICALLY THE WAY PROPERTIES VARY WITH THE ELEMENT’S POSITION IN THE TABLE.
SIMILARITIES AND DIFFERENCES AMONG THE ELEMENTS ARE EASIER TO UNDERSTAND AND REMEMBER.
YES, IN SCIENCE THE PERIODIC TABLE SERVES AS A ROAD MAP IN OUR JOURNEY IN CHEMISTRY.
