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Elements.

posted May 17, 2015, 1:50 PM by Upali Salpadoru   [ updated Dec 1, 2015, 3:51 PM ]

The ancients believed that everything is made up of five elements. They were Earth,. Water, Fire, Air and Akasha (Sky or Space).  The fact that they believed everything may be composed of an aggregate of simpler things is valid even today. More over this division coincides with the four states of matter as we understand today; solid. liquid, gas and plasma.

Looking for a modern definition this is what we got:-

1.       A fundamental, essential, or irreducible constituent of a composite entity. ……..Yahoo.

2.       Chemistry : one of the basic substances that are made of atoms of only one kind and that cannot be separated by ordinary chemical means into simpler substances. ………Merrium Webster Dictionary.

3.       A chemical element is a pure chemical substance consisting of a single type of atom distinguished by its atomic numbert………  Wikipedia.

The Periodic table lists all the elements in an amzing order showing beautiful patterns.

An element is a substance comprising of one kind of atoms which are chemically identical.

That means they must have the same number of protons and electrons. The neutron number may change. Therefore the atomic mass may differ. The atoms of the same element having different number of neutrons are called ‘isotopes'.

In the study of elements, there are certain terms that we have to be familiar with:-

Atomic number- 

If you arrange all the atoms of different elements, starting from the lightest to the heaviest, the rank number is the atomic number. The present day Periodic Table is arranged according to this order. This number is equal to the number of protons in the nucleus.

Mass number:-

The massive sub atomic particles of an atom are the protons and neutrons. The sum of these give the atomic mass or the mass number. (Electrons have negligible mass)

Atomic weight:- 

This is really a measure of mass. So you may even call it Atomic mass. This is calculated as an average mass of the different isotopes present in a sample. Chlorine has many isotopes. The two most common are the Chlorine – 35 and chlorine – 37. Using their natural abundance we can calculate the Atomic weight or atomic mass.

Here is a worked out example:-

Isotope

Mass

Abundance

35Cl

34.97

75.78 %

37Cl

36.97

24.22 %

Total mass of 75.78 atoms of chlorine-35   = 2650.03 units.

Total mass of 24.22 atoms of chlorine- 37 =  895.41 u

Total   of 100 atoms of chlorine sample     = 3545.44 u

Average mass of a chlorine atom               = 35.5 u.

 

Atomic mass unit  (amu).  :-

This is approximately the mass of a Proton. 1 gram is equal to 6 23  amu.

AMU is defined as the 1/12 the mass of a carbon -12 isotope. This is also called a dalton and indicated by ‘Da’.

 

Name / State

Symbol / Valency

Discovery

Remarks

Hydrogen

gas

1H1.008+  Henry Cavendish

1766,

 

The lightest element.  Colourless, 75% of atoms in the Universe are these, (formed during the Big-bang.) This is a metal under very low temperatures as in Jupiter.

Helium

gas

2He4.003

p.janssen

N. Lockyer

1868

 

Second lightest element; Colourless; rare in Earth but there is plenty in the Universe. Only non-metal ending in ‘ium’. Presence was recognised in the sun prior to discovery.   (Named in honour of Sun God)

Lithium soft solid

3Li 6.94 + Arfwedson

1817

Alkali metal, Silvery.        Kept in oil due to high reactivity.  Lightest metallic solid.

Berrilium solid

4Be 9.02++

1797

Alkaline earth, Grey metal.

Boron

solid

5B 10.61

1808

Black shiny, Semi metal (metalloid), semi-conductor.  Resistant to attack by acids.

Carbon

solid

6C 12.01

Ancient

This has the highest boiling point 3500˚ C. Graphite is a black conductor,           Diamond=Colourless semi-conductor;

Carbon forms the largest number of compounds. Present in all living things.

Nitrogen gas

7N 14.01 - - -

1772

4/5th of the atmosphere. Important constituent in animal and plant matter.

Oxygen

gas

8O 16 --

1772

Supports life and combustion. 1/5th of atmosphere.

Fluorine

gas

9F 19 -

1810

Halide. Most electro negatively reactive element.  Colourless.

Neon

gas

10-Ne 20.12

1898

Ramsay

Inert. Used in discharge tubes which glow in a reddish hue.

Sodium solid

11 Na 22.99

1807

Humphrey Davy

Soft, alkali metal. Imparts yellow orange colour to flame.

Reacts vigorously with cold water.

Never touch it

 

Courtsey   U tube .   

https://www.google.co.nz/?gfe_rd=cr&ei=OzzxVZH7Gq_u8wfUiJugAg&gws_rd=ssl#q=the+periodic+table+song+lyrics


 Periodic Table Song

 

 

There’s Hydrogen and Helium                     

 

Then Lithium and Berylium.

 

Boron, Carbon evertwgere,

 



Nitrogen all through the air.

With Oxygen, so you can breathe,

 


And Fluorine for your pretty teeth.

Neon to light up the signs

Sodium for salty times.

 


Magnesium, Aluminium , Silicon, Phosphorus,

Then Sulphur, Chlorine and Argon,

 

Potassium and Calcium so you’ll grow strong,

Scandium, Titanium, Vanadium and Chromium

                                                            and Manganese

This is the Periodic Table.

Noble gas is stable,

Halogen and Alkali metals react aggressively.

Each period we’ll see new outer shells

While electrons are added, moving to the right.










Iron is the 26th

Then Cobalt,Nickel coins you get,

Copper, Zinc and Gallium,

Germanium and Arsenic,

 

Selenium, Bromine film

 

While Krypton helps light up your room.

 

Rubidium and Strontium,

Then Yttrium and Zirconium,

 

Niobium, Molybdenum,

Technotium, Ruthenium,

Rhodium, Palladium,

Silverware,

Then Cadmium and Indium,

 

 

 

Tin cans, Antimony,

 

Then Tellrium, Iodine and Xenon.

 

Theen Caesium and Barium is 56th

 

And this is where the table splits,

 

Where Lanthanides have just begun.

Lanthanum, Cerium, Prasaedium,

Neodium is next.

Promethium  then Sumerium 62.

Europium, Gadolinium, Terbium,

 

Dysprosium, Holmium, Erbium, Thulium.

 

 

Ytterbium,Lutetium, Hafnium,

Tantalum, Tungstan then

 

 

 

We are on the Rhenium

 

Osmium and Iridium,

 

Platinum, Gold, to make you rich,

Till you grow old.

Mercury to tell you when it’s realy cold.

Thallium and Lead

Then Bismuth for your tummy,

Polonium, Astatine , Radon and Francium,

Will last a little time.

Radium, Actinium  Actinides 89

Is the Periodic Table.

Noble gas is stable.

Halogen and Alkali react aggressively.

Each period will see

New order shells

While electrons are to the right.

 

Actinium and Thorium

Protactinium, Uranium,

Neptunium and Plutonium,

Americium, Curium and Berkelium

Californium, Einsteinium, Fermium,

 

 

Mendelivium, Lawrencium, Rutherfordium,

 

Dubnium, Seaborgium,

Bohrium, Hassium

Then Meitherium,Darmstadium

Roentgenium, Copernicum

Unantrium, Unan, Unan …..

Then we are done.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Element name

Element symbol

Atomic number

Hydrogen

H

1

Helium

He

2

Lithium

Li

3

Beryllium

Be

4

Boron

B

5

Carbon

C

6

Nitrogen

N

7

Oxygen

O

8

Fluorine

F

9

Neon

Ne

10

Sodium

Na

11

Magnesium

Mg

12

Aluminium (aluminum)

Al

13

Silicon

Si

14

Phosphorus

P

15

Sulfur (Sulphur)

S

16

Chlorine

Cl

17

Argon

Ar

18

Potassium

K

19

Calcium

Ca

20

Scandium

Sc

21

Titanium

Ti

22

Vanadium

V

23

Chromium

Cr

24

Manganese

Mn

25

Iron

Fe

26

Cobalt

Co

27

Nickel

Ni

28

Copper

Cu

29

Zinc

Zn

30

Gallium

Ga

31

Germanium

Ge

32

Arsenic

As

33

Selenium

Se

34

Bromine

Br

35

Krypton

Kr

36

Rubidium

Rb

37

Strontium

Sr

38

Yttrium

Y

39

Zirconium

Zr

40

Niobium

Nb

41

Molybdenum

Mo

42

Technetium

Tc

43

Ruthenium

Ru

44

Rhodium

Rh

45

Palladium

Pd

46

Silver

Ag

47

Cadmium

Cd

48

Indium

In

49

Tin

Sn

50

Antimony

Sb

51

Tellurium

Te

52

Iodine

I

53

Xenon

Xe

54

Caesium (Cesium)

Cs

55

Barium

Ba

56

Lanthanum

La

57

Cerium

Ce

58

Praseodymium

Pr

59

Neodymium

Nd

60

Promethium

Pm

61

Samarium

Sm

62

Europium

Eu

63

Gadolinium

Gd

64

Terbium

Tb

65

Dysprosium

Dy

66

Holmium

Ho

67

Erbium

Er

68

Thulium

Tm

69

Ytterbium

Yb

70

Lutetium

Lu

71

Hafnium

Hf

72

Tantalum

Ta

73

Tungsten

W

74

Rhenium

Re

75

Osmium

Os

76

Iridium

Ir

77

Platinum

Pt

78

Gold

Au

79

Mercury

Hg

80

Thallium

Tl

81

Lead

Pb

82

Bismuth

Bi

83

Polonium

Po

84

Astatine

At

85

Radon

Rn

86

Francium

Fr

87

Radium

Ra

88

Actinium

Ac

89

Thorium

Th

90

Protactinium

Pa

91

Uranium

U

92

Neptunium

Np

93

Plutonium

Pu

94

Americium

Am

95

Curium

Cm

96

Berkelium

Bk

97

Californium

Cf

98

Einsteinium

Es

99

Fermium

Fm

100

Mendelevium

Md

101

Nobelium

No

102

Lawrencium

Lr

103

Rutherfordium

Rf

104

Dubnium

Db

105

Seaborgium

Sg

106

Bohrium

Bh

107

Hassium

Hs

108

Meitnerium

Mt

109

Darmstadtium

Ds

110

Roentgenium

Rg

111

Copernicium

Cp

112

Ununtrium

Uut

113

Ununquadium

Uuq

114

Ununpentium

Uup

115

Ununhexium

Uuh

116

Ununseptium

Uus

117

Ununoctium

Uuo

118

            

            

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