SURROUNDING OBJECTS
• Solids have specific volume. The amount of matter contained in any object is its mass. So, every theme Gained significant mass and volume.
• Atoms too and molecules These can be measured with a unit called Nanometer.
Very much are small (1 nanometer = 10 meters) properties of particles of matter
• There is space between the molecules of matter.
• Molecules of matter are constantly mixing with each other.
• In matter there is a force of attraction between the molecules. • This protein binds molecules together. For molecules
The gravitational force between objects changes matter. Materials are hard and soft.
Colorless, colorless, liquid, gaseous etc. are the properties of their atoms and molecules Depends on the setting.
Types of substances based on their physical state are solid, liquid, water Also, iyibu is basically element, compound, compound enout
Can be classified. Positions of objects Matter exists in three physical states: solid, liquid, and gas Solidity containing
• Specific Solid in shape, size, bulk. For molecules in solids The molecules are very close together because of the strong gravitational force. Solids are generally incompressible. • Mass required to change the shape of the solid. It is also more robust Energy pressure
They also have the inability to shrink in position Generally, more density and less heat
Themes
It also has expansive properties. Also found in two levels. The fourth state of matter is plasma - a superheated gaseous state. The fifth state of matter is a Bose-Einstein condensate solid.) cooled
liquid
A liquid has a specific volume. But, it does not have a fixed form. • Because gravity in liquid is less than that in solids. The force is solid
• Liquids change their shapes easily because the molecules are not close together. • Are unable to contract under moderate stress.
When heated, they expand more than solids and change to gaseous state. Their density is less than that of solids.
gas
Molecules and atoms in gaseous substances are spread throughout the container. They have no specific size or shape. In gases, the force of attraction between molecules is very weak. So the distance between the molecules is very large. Gas molecules are spread throughout the container. Gases can be compressed more easily compared to solid and liquid states.
Water exists in three states.
solid (ice)
Liquid (Water)
Gas (Steam)
• The kinetic energy of the particles (molecules / atoms) in the solid increases when the temperature of the solid is raised.
* The temperature at which a solid melts and turns into a liquid is called the melting point of the solid. The melting point of ice is O°C.
• When a liquid is heated the particles (molecules/atoms) in the liquid start moving faster.
• A certain interval increases. At this temperature the liquid turns into a gas.
For molecules at temp
• The temperature at which a liquid begins to boil is called its boiling point. Boiling point of water is 100°C.
• Molecules in liquid have high thermal energy
get and become vapor.
There are two types of changes
Physical change
Chemical change
Physical changes
Crystals of pure substances are obtained from their solutions. This process is called crystallization. The resulting crystal will have a specific shape and different sizes.
Sublimation is the phenomenon in which a solid substance (camphor) changes directly into a gaseous state without becoming a liquid when heated.
Ice turns into water when heated. This is called melting. * If water is continuously heated, water boils and turns into steam
changes. This is called evaporation.
If water vapor is cooled it turns back into water. This phenomenon is called cooling.
If water is cooled further it turns into ice. For example, when water is placed in a cooling device, water turns into ice. This is called freezing. A change in the physical properties of a substance is called a physical change. Physical change is usually reactive. No new objects are formed.
Chemical changes
Iron combines with oxygen and water in the air to form iron oxide. This is what we call rust. Water and oxygen are essential for rusting.
Magnesium tape burning is a chemical change. Burning wax is a chemical change.
When wax burns, its molecules turn into carbon dioxide and water.
The aroma, color and taste in vegetables and fruits are due to the presence of phenolic compounds in them. Phenolic compounds may also prevent heart disease and some types of cancer.
• Cut pods or fruits and air them for some time Turns brown when placed. Why? Do you know?
A chemical called phenolic compound in nuts and fruits reacts with oxygen in the air to turn into a brown substance called melanin.
Chemical reaction of lemon juice with baking soda. The transformation of milk into curd is a chemical transformation.
Utensils made of silver lose their luster over time due to chemical changes. The luster goes away as the vessels react with the sulfur in the air. Using chemistry
Again the dishes can be polished. Reactants react to give more than one product. This is called a chemical change.)
When chemical changes take place * heat and light are emitted or sound is inhaled The color changes and the smell changes
To prevent rusting
• Shielding with paint or lubricant • Copper plating (coating of zinc on iron) • Coating of chromium on iron
Plating silver metal on iron
Acids, bases and salts in everyday life
• The word acid is derived from the Latin word acidus. The meaning of this word is sour. • Acids displace hydrogen
received
• Acids are of two types. Organic acids, fruit
acids
Organic acids
• From plants and animals
Acids are organic acids.
• Vinegar (acetic acid)
• Lemons and oranges (citric acid)
• Apple (malic acid) • Ant (formic acid)
• Milk (lactic acid)
• Grapes (tartaric acid) • Tomatoes (oxalic acid)
Mineral acids
• Acid obtained from mineral substances is called mineral acid. For example hydrochloric acid (HCI), sulfuric acid (H,SO,) and nitric acid (HNO.)
• These acids are corrosive to skin and also corrosive to metals. Does not corrode glass and pottery.
alkalis
Metal oxide and hydroxide compounds are called bases.
• Alkalis like sodium hydroxide (erysoda) and potassium hydroxide (erypotassium) are corrosive.
• Alkalis combine with water to give hydroxide ion.
• Water soluble bases are called 'Alkalis'.
All alkalis are bases. But not all bases are alkalis. The word Alkali comes from the Arabic word. It means wood ash.
Cells in the human body contain deoxyribonucleic acid (DNA). These control the activities of cells. For example these cells are responsible for human body structure, color and height. Proteins help in body structure. Protein contains amino acids. Fat contains fatty acids.
Properties of acids
• Sour taste. Corrosive
Generally all acids contain hydrogen. However, not all compounds containing hydrogen are acids. Eg. Methane (CH,) Ammonia(NH,) and Glucose(CH,2O )
Acids react with metals to form hydrogen expels gas.
Metal + Acid Salt + Hydrogen t Acids turn blue litmus paper red. Color too
(Acids do not react with the colorant of fenaphthalin.
Acids give a red color with methyl orange dye. Acids are good conductors of electricity.
Uses of inorganic acids • Used in chemical laboratories.
Dyes, Medicines, Fertilizers, Explosives and Perfumes
Used in industries that manufacture liquids.
and for the separation of metals from ores
and resin from bones are used.
To separate Acids, carbon dioxide, hydrogen sulfide. Also to produce gases like hydrogen and sulfur dioxide are used. Also used to refine petroleum.