can anyone explain me ch 2 matter is us pure of cbse class 9
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Anything that has mass and occupies space is called matter all matter exists in one of these 3 states solid liquid and gas.
________________________________CHARACTERISTICS OF MATTER
An element is defined as a substance that cannot be subdivided into two or more simpler substances by any physical or chemical method ,there are 118 elements of which 92 are natural and the remaining are synthetic. The smallest unit of an element is called an atom an atom is defined as the smallest unit of an element that may or may not have an independent existence and always takes part in a chemical reaction. Two or more elements combine to form a molecule, a molecule is defined as the smallest unit of matter that has an independent existence and carries the physical and chemical properties of that matter. For example, 1 molecule of oxygen consists of two atoms of oxygen whereas 1 molecule of water consists of two atoms of hydrogen and one atom of oxygen . Atoms and molecules are too small to be seen even under a powerful microscope.
KEY POINT : Molecule in a substance remain in continuous motion for example the fragrance of an incense stick lit in one corner of a room fills of the entire room in a short while another example is a drop of ink of water colour gets mixed with a glass of water within a short time.
______________________________________KINETIC THEORY OF MATTER :
1. All matter is made up of molecules that are in a state of continuous motion and thus possesses kinetic energy.
2. The kinetic energy of the molecule is directly proportional to the amount of heat possessed by the object.
3. Molecule in a substance always exerts a force of attraction on each other this force is known as the intermolecular force of attraction, the force of attraction between molecules of the same kind is called the force of Cohesion and the force of attraction between molecules of different kinds is called the force of adhesion , the gaps between the different molecules in a substance are called intermolecular spaces.
__________________________________TRANSFER OF HEAT :
Transfer of heat takes place by three methods conduction and Convection
1. CONDUCTION : the mode of transfer of heat from one molecule to another without the actual movement of molecules from the mean position is called conduction.
2. CONVECTION: the mode of transfer of heat energy where the particles of a fluid actually move from a place of higher temperature to a place of lower temperature is called convection.
_____________________________________KEY POINT : Due to a net intermolecular force on the molecules on the surface of a liquid the liquid surface behaves like inelastic stretched membrane this property of liquid is called surface tension.
Hope it helps
________________________________CHARACTERISTICS OF MATTER
An element is defined as a substance that cannot be subdivided into two or more simpler substances by any physical or chemical method ,there are 118 elements of which 92 are natural and the remaining are synthetic. The smallest unit of an element is called an atom an atom is defined as the smallest unit of an element that may or may not have an independent existence and always takes part in a chemical reaction. Two or more elements combine to form a molecule, a molecule is defined as the smallest unit of matter that has an independent existence and carries the physical and chemical properties of that matter. For example, 1 molecule of oxygen consists of two atoms of oxygen whereas 1 molecule of water consists of two atoms of hydrogen and one atom of oxygen . Atoms and molecules are too small to be seen even under a powerful microscope.
KEY POINT : Molecule in a substance remain in continuous motion for example the fragrance of an incense stick lit in one corner of a room fills of the entire room in a short while another example is a drop of ink of water colour gets mixed with a glass of water within a short time.
______________________________________KINETIC THEORY OF MATTER :
1. All matter is made up of molecules that are in a state of continuous motion and thus possesses kinetic energy.
2. The kinetic energy of the molecule is directly proportional to the amount of heat possessed by the object.
3. Molecule in a substance always exerts a force of attraction on each other this force is known as the intermolecular force of attraction, the force of attraction between molecules of the same kind is called the force of Cohesion and the force of attraction between molecules of different kinds is called the force of adhesion , the gaps between the different molecules in a substance are called intermolecular spaces.
__________________________________TRANSFER OF HEAT :
Transfer of heat takes place by three methods conduction and Convection
1. CONDUCTION : the mode of transfer of heat from one molecule to another without the actual movement of molecules from the mean position is called conduction.
2. CONVECTION: the mode of transfer of heat energy where the particles of a fluid actually move from a place of higher temperature to a place of lower temperature is called convection.
_____________________________________KEY POINT : Due to a net intermolecular force on the molecules on the surface of a liquid the liquid surface behaves like inelastic stretched membrane this property of liquid is called surface tension.
Hope it helps
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