chemistry adda: CBSE 10TH chemistry Guess paper for 2011

chemistry adda: CBSE 10TH chemistry Guess paper for 2011: Chemical and chemical reaction Acid Base and Salts Metals and Non Metals Periodic Classification of Elements For more http://jsuniltuto...

Electronic Configurations of elements in periodic table

1 -

1.Hydrogen: 1s1	2 - Helium: 1s2
3 – Lithium: [He], 2s1	4 – Beryllium: [He], 2s2
5 – Boron: [He], 2s2, 2p1	6 – Carbon: [He], 2s2, 2p2
7 – Nitrogen: [He], 2s2, 2p3	8 – Oxygen: [He], 2s2, 2p4
9 – Fluorine: [He], 2s2, 2p5	10 – Neon: [He], 2s2, 2p6
11 - Sodium: [Ne], 3s1	12 - Magnisium: [Ne], 3s2
13 – Aluminum: [Ne], 3s2, 3p1	14 – Silicon: [Ne], 3s2, 3p2
15 – Phosphorus: [Ne], 3s2, 3p3	16 – Sulfur: [Ne], 3s2, 3p4
17 – Chlorine: [Ne], 3s2, 3p5	18 - Argon: [Ne], 3s2, 3p6
19 – Potassium: [Ar], 4s1	20 – Calcium: [Ar], 4s2
21 – Scandium: [Ar], 4s2, 4d1	22 – Titanium: [Ar], 4s2, 4d2
23 – Vanadium: [Ar], 4s2, 4d3	24 – Chromium: [Ar], 4s2, 4d4
25 – Manganese: [Ar], 4s2, 4d5	26 – Iron: [Ar], 4s2, 4d6
27 – Cobalt: [Ar], 4s2, 4d7	28 – Nickel: [Ar], 4s2, 4d8
29 – Copper: [Ar], 4s2, 4d9	30 – Zinc: [Ar], 4s2, 4d10
31 – Gallium: [Ar], 4s2, 4d10, 4p1	32 – Germanium: [Ar], 4s2, 4d10, 4p2
33 – Arsenic: [Ar], 4s2, 4d10, 4p3	34 – Selenium: [Ar], 4s2, 4d10, 4p4
35 – Bromine: [Ar], 4s2, 4d10, 4p5	36 – Krypton: [Ar], 4s2, 4d10, 4p6
37 – Rubidium: [Kr], 5s1	38 – Strontium: [Kr], 5s2
39 – Yttrium: [Kr], 5s2, 3d1	40 – Zirconium: [Kr], 5s2, 3d2
41 – Niobium: [Kr], 5s2, 4d3	42 – Molybdenum: [Kr], 5s2, 4d4
43 – Technetium: [Kr], 5s2, 4d5	44 – Ruthenium: [Kr], 5s2, 4d6
45 – Rhodium: [Kr], 5s2, 4d7	46 – Palladium: [Kr], 5s2, 4d8
47 – Silver: [Kr], 5s2, 4d9	48 – Cadmium: [Kr], 5s2, 4d10
49 – Indium: [Kr], 5s2, 4d10, 5p1	50 – Tin: [Kr], 5s2, 4d10, 5p2
51 – Antimony: [Kr], 5s2, 4d10, 5p3	52 – Tellurium: [Kr], 5s2, 4d10, 5p4
53 – Iodine: [Kr], 5s2, 4d10, 5p5	54 – Xenon: [Kr], 5s2, 4d10, 5p6
55 – Cesium: [Xe], 4f1	56 – Barium: [Xe], 4f2
57 – Lanthanum: [Xe], 4f3	58 – Cerium: [Xe], 4f4
59 – Praseodymium: [Xe], 4f5	60 – Neodymium: [Xe], 4f6
61 – Promethium: [Xe], 4f7	62 – Samarium: [Xe], 4f8
63 – Europium: [Xe], 4f9	64 – Gadolinium: [Xe], 4f10
65 – Terbium: [Xe], 4f11	66 – Dysprosium: [Xe], 4f12
67 – Holmium: [Xe], 4f13	68 – Erbium: [Xe], 4f14
69 – Thulium: [Xe], 4f14, 5d1	70 – Ytterbium: [Xe], 4f14, 5d2
71 – Lutetium: [Xe], 4f14, 5d3	72 – Hafnium: [Xe], 4f14, 5d4
73 – Tantalum: [Xe], 4f14, 5d5	74 – Tungsten: [Xe], 4f14, 5d6
75 – Rhenium: [Xe], 4f14, 5d7	76 – Osmium: [Xe], 4f14, 5d8
77 – Iridium: [Xe], 4f14, 5d9	78 – Platinum: [Xe], 4f14, 5d10
79 – Gold: [Xe], 4f14, 5d10, 6s1	80 – Mercury: [Xe], 4f14, 5d10, 6s2
81 – Thallium: [Xe], 4f14, 5d10, 6s2, 6p1	82 – Lead: [Xe], 4f14, 5d10, 6s2, 6p2
83 – Bismuth: [Xe], 4f14, 5d10, 6s2, 6p3	84 – Polonium: [Xe], 4f14, 5d10, 6s2, 6p4
85 – Astatine: [Xe], 4f14, 5d10, 6s2, 6p5	86 – Radon: [Xe], 4f14, 5d10, 6s2, 6p6
87 – Francium: [Rn], 5f1	88 – Radium: [Rn], 5f2
89 – Actinium: [Rn], 5f3	90 – Thorium: [Rn], 5f4
91 – Protactnium: [Rn], 5f5	92 – Uranium: [Rn], 5f6
93 – Neptunium: [Rn], 5f7	94 – Plutonium: [Rn], 5f8
95 – Americium: [Rn], 5f9	96 – Curium: [Rn], 5f10
97 – Berkelium: [Rn], 5f11	98 – Calfifornium: [Rn], 5f12
99 – Einsteinium: [Rn], 5f13	100 – Fermium: [Rn], 5f14
101 – Mendelevium: [Rn], 5f14, 6d1	102 – Nobelium: [Rn], 5f14, 6d2
103 – Lawrencium: [Rn], 5f14, 6d3	104 - Rutherfordium: [Rn], 5f14, 6d4
105 - Dubnium: [Rn], 5f14, 6d5	106 – Seaborgium: [Rn], 5f14, 6d6
107 – Bohrium: [Rn], 5f14, 6d7	108 – Hassium: [Rn], 5f14, 6d8
109 – Meitnerdium: [Rn], 5f14, 6d9	110 – Darmstadtium: [Rn], 5f14, 6d10
111 – Roentgenium: [Rn], 5f14, 6d10, 7s1	112 – Ununbium: [Rn], 5f14, 6d10, 7s2
113 – Ununtrium: [Rn], 5f14, 6d10, 7s2, 7p1	114 – Ununquadium: [Rn], 5f14, 6d10, 7s2, 7p2
115 – Ununpentium: [Rn], 5f14, 6d10, 7s2, 7p3	116 – Ununhexium: [Rn], 5f14, 6d10, 7s2, 7p4
117 – Ununseptium: [Rn], 5f14, 6d10, 7s2, 7p5	118 – Ununoctium: [Rn], 5f14, 6d10, 7s2, 7p6

CBSE 10TH chemistry Guess paper for 2011

Chemical and chemical reaction
Acid Base and Salts
Metals and Non Metals
Periodic Classification of Elements
For more http://jsuniltutorial.weebly.com/science1.html

9th Quick revision E Notes for chapter Structure of Atom

(a) The smallest particle of a matter that takes part in a chemical reaction is called an atom. The atom of all gases except those of noble gases, cannot exist in free state. These exist in molecular form. The molecules of hydrogen, nitrogen, oxygen and halogens are diatomic (H2, N2). Phosphorus molecule is tetratomic and that of sulphur is octa atomic.

(b) The smallest particle of a matter that can exist in free state in nature, is known as a molecule.

(c) Some molecules are composed of homoatomic atom, e.g., H2, O2, N2, Cl2, O3 etc., while the molecules of compounds are made up of two or more heteroatomic atoms e.g., HCl, NaOH, HNO3, CaCO3, etc.

DALTON’S ATOMIC THEORY

The concepts put forward by John Dalton regarding the composition of matter are known as Dalton’s atomic theory. Its important points are as follows.

(a) Every matter is composed of very minute particles, called atoms that take part in chemical reactions.

(b) Atoms cannot be further subdivided.

(c) The atoms of different elements differ from each other in their properties and masses, while the atoms of the same element are identical in all respects.

(d) The atoms of different elements can combine in simple ratio to form compounds. The masses of combining elements represent the masses of combining atoms.

(e) Atom can neither be created nor destroyed.

MODERN CONCEPT

Many of the concepts of Dalton’s atomic theory cannot be explained. Therefore, foundation of modern

atomic theory was laid down by the end of nineteenth century. The modern theory is substantiated by the existence of isotopes, radioactive disintegration, etc. The important points of the modern atomic theory are as follows.

(a) Prof. Henri Bacquerel discovered the phenomenon of radioactivity and found that an atom is divisible.

(b) An atom is mainly composed of three fundamental particles, viz. electron, proton and neutron.

(c) Apart from the aforesaid three fundamental particles, many others have also been identified, viz. positron, meson, neutrino, antiproton, etc.

(d) Soddy discovered the existence of isotopes, which were atom of the same element having different masses.
For example, protium, deuterium and tritium are atoms of hydrogen having atomic masses 1, 2 and 3 a.m.u. respectively.

(e) Atoms having same mass may have different atomic numbers. These are known as isobars. For example, 40/18 Ar ,and 40/20Ca

(f) Atoms of elements combines to form molecules.

(g) It is not necessary that the atoms should combine in simple ratio for the formation of compounds. The atoms in non-stoichiometric compounds are not present in simple ratio. For example, in ferrous sulphide crystals, iron and sulphur atoms are present in the ratio of 0.86 : 1.00.

(h) Atoms participate in chemical reactions.

CATHODE RAYS (DISCOVERY OF ELECTRON)

Dry gases are normally bad conductors of electricity. But under low pressure, i.e., 0.1 mm of mercury or
lower, electric current can pass through the gases. Julius Plucker in 1859 found that a type of rays, called cathode rays, emit from the cathode when electricity is passed through a discharge tube. William Crookes (1879), J.J.Thomson and many other scientists studied the properties of cathode rays and came to the conclusion that the cathode rays of same properties are obtained using any gas or any cathode material
The salient features of cathode ray are as follows.
(a) Cathode rays travel in a straight line. This indicates that the formation of a shadow when an opaque object is placed in its path.
(b) If a light metal pinwheel is placed in the path of cathode rays, the wheel starts revolving. This proves that is cathode rays consist of tiny particles having momentum.
(c) Cathode rays get deviated in electrical and magnetic fields. This proves that they are composed of charged particles. Their derivation towards anode indicates their negatively charged nature. The direction of their deviation in magnetic field depends on pole of the magnet which has been placed near the cathode ray tube.
(d) Cathode rays produce green fluorescence on the walls of the glass tube.
(e) Cathode rays produce incandescence in at thin metal foil.
(f) Cathode rays effect the photographic plate.
(g) Cathode rays ionize gases proving that they are charged.
(h) Cathode rays penetrates across a thin metal foil.
(i) Cathode rays produce X-rays when they hit a piece of tungsten or any other metal having high melting point

POSITIVE RAYS OR CANAL RAYS : DISCOVERY OF PROTON

Eugene Goldstein in 1886 found that a dim glow is visible behind the cathode when an electric discharge is passed through a perforated cathode in a discharge tube filled with a gas at low pressure. These new type of rays travel from anode to that cathode. Goldstein gave the name canal rays to these rays because these rays cross the canals of the cathode and reach the other side. W.Wein in 1897 proved through experiments that the canal rays consist of positively charged particles. J.J. Thomson gave the name positive rays to them because they are composed of positively charged particles.

DISCOVERY OF NEUTRON

Penetrating rays are emitted on bombarding α-particles on the elements like beryllium, boron and aluminium.James Chadwick in 1932 studied the nature of these radiation and came to the conclusion that these rays are composed of very tiny electro neutral particles. The mass of these particles is almost equal to that of the hydrogen atom. This particle is called neutron and is denoted by the symbol, ₀n¹ 
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DISCOVERY OF THE NUCLEUS

J.J.Thomson’s atomic theory explained electrical neutrality of atoms, it could not reveal the presence of nucleus in an atom, which was later in 1909 proposed by Ernest Rutherford

A stream of alpha particles was made to pass through a thin gold foil of about  4x10-5 cm thickness. Most of the alpha particles did go through the foil in a straight line. Some alpha particles were deflected through an average angle of 90o .Rarely the path of 1 in 20,000 alpha particles scored a direct hit on the nucleus and returned by an angle of 180o.

He concluded that there is a heavy positive charge occupying small volume, at the centre of an atom. The atom consisting of a small, dense, positively charged nucleus containing most of the mass of the atom with the electrons in the space outside the nucleus .The moving electrons occupy most of the volume of the atom. The electrons must be moving very rapidly in the space around the nucleus.

He state a moving electron should accelerate and continuously lose energy. Due to the loss of energy, path of electron may reduce and finally the electron should fall into nucleus.

This is not true

If it happens so, atom becomes unstable. But atoms are stable. Hence Rutherford’s theory was unable to explain the stability of atom.

Niel’s Bohr modified Rutherford’s atom model and put forth the following postulates.

• In atoms, the electrons revolve around the nucleus in stationary circular paths. These paths are called

• orbits or shells or energy levels. 

• As long as electrons revolve in the same orbit, it does not lose or gain energy. 

• The circular orbits are numbered as 1, 2, 3, 4 or designated as K, L, M, N shells. These numbers are referred to as principal quantum numbers (n). 

• Smaller the size of orbit, smaller is the energy of the orbit. 

• As we move away from nucleus, energy of orbit is constantly increasing. 

• Maximum number of electrons that can be accommodated in an energy level (n) is given by 2n2 

• When an electron absorbs energy, it jumps from lower energy level to higher energy level. 

• When an electron returns from higher energy level to lower energy level, it gives off energy.

The fundamental particles of an atom are,

Protons: They are positively charged particles. They are present inside the  nucleus.

Electrons: They are negatively  charged particles. They revolve around the nucleus in circular orbits.

Neutrons: They are neutral particles.  They are present inside the nucleus.

Protons are positively charged.  Protons repel each other because of their like-charges. Hence, more than one proton cannot be packed in a small volume to form a stable nucleus unless  neutrons are present.

Neutrons reduce the repulsive force  between positively charged protons and contribute to the force that holds the particles in the nucleus together.

Atomic number

Atom as a whole is electrically neutral. It is due to the presence of equal number of protons and electrons. This number is referred to as atomic number.

Atomic number  =  The number of protons in the nucleus

Atomic number  = The number of electrons revolving around the nucleus.

Mass number : the mass of an atom  entirely depends on the mass of nucleus.

The mass of the lightest atom, hydrogen  has been chosen as the unit of mass.

Since the nucleus of an atom contains protons and neutrons, mass number (A) is defined

as, the sum of the number of protons and neutrons in the nucleus of an atom

Mass Number (A) = Number of protons + Number of neutrons

Representation of Atomic number and  Mass number

Superscript represents mass number.      Subscript represents atomic number.

For example, Atomic number of nitrogen is 7. Mass number of nitrogen is 14.

Representation:  

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