Valence Meaning Mass Number Atomic Number of Elements

Valence Meaning Mass Number Atomic Number of Elements Valence meaning, Valency of copper, valency of zinc, Valency of silver, Mass Number Hello learners in the online tutoring class we read chemistry chapter valency. In this chapter many questions will be answered in this lesson. Like What is valence meaning? What is Valency? We also learn about important elements valency like valency of copper, valency of zinc, valency of silver etc This is very helpful to get maximum marks relative this chapter. In this chapter we also discuss about Atomic Mass number. Because Questions related to Atomic mass number are often asked. This is a very important chapter. In addition to this, we will also study about the chemical symbol of elements. like this potassium symbol, iron symbol, oxygen symbol, lithium symbol etc. about 118 elements and their symbols. Chemical symbol is very important for studying chemistry. 

Valence meaning, Valency of copper, valency of zinc, Valency of silver, Mass Number

Valence Meaning

An atom of each element has a definite combining capacity, called its valency.
We know how the electrons in an atom are arranged in different shells/orbits. The electrons present in the outermost shell of an atom are known as the valence electrons,
From the Bohr-Bury scheme, we also know that the outermost shell of an atom can accommodate a maximum of 8 electrons. It was observed that the atoms of elements, completely filled with 8 electrons in the outermost shell show little chemical activity. In other words, their combining capacity or valency is zero. Of these inert elements, the helium atom has two electrons in its outermost shell and all other elements have atoms with eight electrons in the outermost shell.

The combining capacity of the atoms of elements, that is, their tendency to react and form molecules with atoms of the same or different elements, was thus explained as an attempt to attain a fully-filled outermost shell. An outermost-shell, which had eight electrons was said to possess an octet. Atoms would this react, so as to achieve an octet in the outermost shell. This was done by sharing, gaining or losing electrons. The number of electrons gained, lost or shared so as to make the octet of electrons in the outermost shell, gives us directly the combining capacity of the element, that is, the valency discussed in the previous chapter.
For example, hydrogen/lithium/sodium atoms contain one electron each in their outermost shell, therefore each one of them can lose one electron. So, they are said to have valency of one. Magnesium valency is two and aluminium valency is three, because magnesium has two electrons in its outermost shell and aluminium has three electrons in its outermost shell.

If the number of electrons in the outermost shell of an atom is close to its full capacity, then valency is determined in a different way. 
For example, the fluorine atom has 7 electrons in the outermost shell, and its valency could be 7. But it is easier for fluorine to gain one electron instead of losing seven electrons. Hence, its valency is determined by subtracting seven electrons from the octet and this gives you a valency of one for fluorine. Valency can be calculated in a similar manner for oxygen.
Here are table given below which show important elements symbols, mass number, atomic number and valency.

Atomic Number Element Name Symbol Atomic  Mass Number Valency
1 Hydrogen H 1.008 +1
2 Helium He 4.003 0
3 Lithium Li 6.941 +1
4 Beryllium Be 9.012 +2
5 Boron B 10.81 -3, +3
6 Carbon C 12.01 +2, +4
7 Nitrogen N 14.01 -3, -2, -1, +1, +2, +3, +4, +5
8 Oxygen O 16.00 -2
9 Florine F 19.00 -1, +1
10 Neon Ne 20.18 0
11 Sodium Na 22.99 +1
12 Magnesium Mg 24.31 +2
13 Aluminium Al 26.98 +3
14 Silicon Si 28.09 -4, +2, +4
15 Phosphorus P 30.97 -3, +1, +3, +5
16 Sulfur S 32.06 -2, +2, +4, +6
17 Chlorine Cl 35.45 -1, +1, +2, +3, +4, +5, +7
18 Argon Ar 39.95 0
19 Potassium K 39.10 +1
20 Calcium Ca 40.08 +2
21 Scandium Sc 44.96 +3
22 Titanium Ti 47.90 +2, +3, +4
23 Vanadium V 50.94 +2, +3, +4, +5
24 Chromium Cr 52.00 +2, +3, +6
25 Manganese Mg 54.94 +2, +3, +4, +6, +7
26 Iron Fe 55.85 +2, +3, +4, +6
27 Cobalt Co 58.93 +1, +2, +3, +4
28 Nickel Co 58.70 +2, +3, +4
29 Copper Cu 63.55 +1, +2, +3
30 Zinc Zn 65.38 +2
32 Gallium Ga 69.72  
33 Arsenic As 74.92  
34 Selenium Se 78.96  
36 Bromine Br 79.90  
37 Rubidium Rb 85.47  
38 Strontium Sr 87.62  
39 Yttrium Y 88.91  
40 Zirconium Zr 91.22  
41 Niobium Nb 92.91  
42 Molybdenum Mo 95.94  
43 Technetium Tc 97  
44 Ruthenium Ru 101.1  
45 Rhodium Rh 102.9  
46 Palladium Pd 106.4  
47 Silver Ag 107.9  
48 Cadmium Cd 112.4  
49 Indium In 114.8  
50 Tin Sn 118.7  
51 Antimony Sb 121.8  
52 Tellurium Te 127.6  
53 Iodine I 126.9  
54 Xenon Xe 131.3  
55 Caesium Cs 132.9  
56 Barium Ba 137.3  
57 Lanthanum La 138.9  
58 Cerium Ce 140.1  
59 Praseodymium Pr 140.9  
60 Neodymium Nd 144.2  
61 Promethium Pm 145  
62 Samarium Sm 150.4  
63 Europium Eu 152.0  
64 Gadolinium Gd 157.3  
65 Terbium Tb 158.9  
66 Dysprosium Dy 162.5  
67 Holmium Ho 164.9  
68 Erbium Er 167.3  
69 Thulium Tm 168.9  
70 Ytterbium Yb 173  
71 Lutetium Lu 175  
72 Hafnium Hf 178.5  
73 Tantalum Ta 180.9  
74 Tungsten W 183.9  
75 Rhenium Re 186.2  
76 Osmium Os 190.2  
77 Iridium Ir 192.2  
78 Platinum Pt 195.1  
79 Gold Au 197  
80 Mercury Hg 200.6  
81 Thallium Tl 204.4  
82 Lead Pd 207.2  
83 Bismuth Bi 209.  
84 Polonium Po 209  
85 Astatine At 210  
86 Radon Rn 222  
87 Francium Fr 223  
88 Radium Ra 226  
89 Actinium Ac 227  
90 Thorium Th 232  
91 Protactinium Pa 231  
92 Uranium U 238  
93 Neptunium Np 237  
94 Plutonium Pu 244  
95 Americium Am 243  
96 Curium CM 247  
97 Berkelium Bk 247  
98 Californium Cf 251  
99 Einsteinium Es 254  
100 Fermium Fm 257  
101 Mendelevium Md 258  
102 Nobelium No 259  
103 Lawrencium Lr 260  
104 Rutherfordium Rf 261  
105 Dubnium Db 262  
106 Seaborgium Sg 263  
107 Bohrium Bh 262  
108 Hassium HS 265  
109 Mitnerium  Mt 267  
110 Damstacium Ds Not Confirmed  
111 Roentgentium Rg Not Confirmed  
112 Copernicium Cn Not Confirmed  
113 Ununtrium Uut Not Confirmed  
114 Ununquadium  Uuq Not Confirmed  
115 Ununpentium Uup Not Confirmed  
116 Ununhexium Uuh Not Confirmed  
117 Ununseptium Uus Not Confirmed  
118 Ununoctium Uuo Not Confirmed  

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