Science.docx

**Microorganisms 🦠** **What are Microorganisms?** Microorganisms are tiny living organisms that are too small to be seen with the naked eye. They can be found almost everywhere, including in extreme environmental conditions. **Characteristics of Microorganisms** - They can survive in extreme...

**Microorganisms 🦠** **What are Microorganisms?** Microorganisms are tiny living organisms that are too small to be seen with the naked eye. They can be found almost everywhere, including in extreme environmental conditions. **Characteristics of Microorganisms** - They can survive in extreme heat or cold - They can form a hard outer covering called a cyst, which protects them from harsh conditions - They can be beneficial or harmful to humans **Where are Microorganisms Found?** Microorganisms can be found in: - Rocks - Soil - Water - Air - Deep inside the Earth - Boiling hot springs - Frozen glaciers - Dry deserts - Deep sea - Homes and schools - On the touchpad of mobile phones - On a moist piece of bread - On a log of wood - On the bodies of plants, animals, and even inside the human body **Classification of Microorganisms** Microorganisms can be classified into five main types: **Classification** **Description** -------------------- --------------------------------------------------------------------------------------------------------------------------------------- Bacteria Unicellular, single-celled, tiny organisms that live together in colonies Algae Simple plant-like organisms with cell walls, capable of photosynthesis Fungi Non-green organisms with bodies made of thread-like structures called hyphae Protozoa Unicellular organisms that have animal-like characteristics, lacking cell walls Viruses Extremely tiny organisms that can only be seen with an electron microscope, with characteristics of both living and non-living things **Bacteria** - Shapes: spiral, spherical, rod-shaped, comma-shaped - Sizes: 0.2 to 2 microns - Examples: *Escherichia coli* (E. coli), *Staphylococcus aureus* **Algae** - Types: unicellular (microalgae), multicellular (macroalgae) - Examples: *Chlamydomonas*, *Volvox*, *Fucus*, *Spirogyra* - Characteristics: simple plant-like organisms with cell walls, capable of photosynthesis **Fungi** - Types: saprophytic, parasitic - Examples: yeast, *Rhizopus*, *Agaricus*, *Penicillium* - Characteristics: non-green organisms with bodies made of thread-like structures called hyphae **Protozoa** - Examples: *Paramecium*, *Trypanosoma*, *Amoeba* - Characteristics: unicellular organisms that have animal-like characteristics, lacking cell walls **Viruses** - Examples: influenza virus, poliovirus, bacteriophage - Characteristics: extremely tiny organisms that can only be seen with an electron microscope, with characteristics of both living and non-living things **Useful Microorganisms** Microorganisms are useful to us in several ways, including: - Food industry: fermentation, making bread, dosas, idlis, and dhoklas - Medicine: making antibiotics, vaccines - Agriculture: making fertilizers, pest control\#\# Increasing Soil Fertility 🌱 The amount of nitrogen present in the soil in the form of nitrates and nitrites hugely impacts the soil fertility. Certain bacteria, such as **Nitrobacter**, **Rhizobium**, and blue-green algae like **Nostoc**, convert atmospheric nitrogen into nitrates and nitrites or ammonia, increasing soil fertility. These organisms are referred to as **biological nitrogen fixers**. **Cleaning the Environment + Microbes 🌿** Microbes help in keeping our environment naturally clean by: - Decomposing dead matter Recycling nutrients like nitrogen present in the atmosphere Breaking down many plant and animal waste and producing biogas Cleaning wastewater by producing enzymes Some microorganisms are also used as eco-friendly pesticides, in genetic engineering, copper extraction, and perfume production. **Harmful Microorganisms 😷** Microorganisms can be harmful to us, causing diseases in humans, plants, and animals, as well as spoiling food. Let\'s study more about them. **Microbes Causing Diseases** **Pathogens** or **germs** are microorganisms that cause diseases. Germs generally enter the body of living organisms through: - The air we breathe The water we drink The food we eat Direct or indirect contact with an infected person or carrier Diseases that can spread from an infected person to a healthy individual through air, water, or direct contact are called **communicable diseases**. Some examples of such diseases are: **Disease** **Caused by** -------------- --------------- Cholera Bacteria Typhoid Bacteria Hepatitis Virus Common Cold Virus Chicken Pox Virus Tuberculosis Bacteria AIDS Virus **Vector-Borne Diseases** Insects like houseflies, mosquitoes, and cockroaches are vectors or carriers of various diseases. **Disease** **Caused by** **Vector** -------------- ------------------------ --------------------------- Malaria Plasmodium (protozoan) Female Anopheles mosquito Dengue Fever Dengue virus Female Aedes mosquito Typhoid Bacteria Houseflies \"The easiest way to kill germs from water is to boil it for at least 10 minutes.\" **Spoiling Food** Microorganisms can spoil food by: - Growing on food items and producing toxic substances Causing fermentation and spoiling packed juices If contaminated food is consumed, it can lead to symptoms of food poisoning such as nausea, vomiting, abdominal cramps, and diarrhea. **Food Preservation** Foods can be protected from getting spoiled by following various techniques: **Technique** **Description** ---------------------------- ------------------------------------------------------------------------ Heating Kills most microorganisms by boiling or pasteurization Cooling Slows down the growth of microorganisms by refrigeration or freezing Adding Salt or Sugar Reduces moisture content and prevents growth of microorganisms Dehydration Removes water, preventing microbial growth Adding Oil or Vinegar Creates an unfavorable environment for microbial growth Chemical Preservation Inhibits growth of microorganisms using chemicals like sodium benzoate Canning and Vacuum Packing Keeps microorganisms away by sealing food in airtight containers \"Microorganisms can cause diseases in humans, animals, and plants. They can also be used in preparation of cakes, bread, and idlis, and help in cleaning our environment by decomposing dead organic matter.\" **Definition of Force** A push or pull that affects an object in some way is called a force. **Force** is a measurable quantity. The SI unit of the magnitude of force is **newton** (denoted by N). Force also has a direction. **Effects of Force** - **Make a stationary object move**: A force can cause a stationary object to move, such as when a player kicks a football. - **Change the speed of a moving object**: A force can increase or decrease the speed of a moving object, such as when a moving trolley is pushed or pulled. - **Stop a moving object**: A force can bring a moving object to rest, such as when a goalkeeper stops a football. - **Change the direction of a moving object**: A force can change the direction of a moving object, such as when a batsman hits a ball. - **Change the shape of an object**: A force can change the shape and size of an object, such as when children push and pull clay dough to make toys. **Types of Force** **Contact Force** A force that requires physical contact between objects is called a **contact force**. **Type of Contact Force** **Description** --------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------ Muscular Force A force that requires the action of muscles of our body, such as pushing, pulling, throwing, kicking, lifting, running, jumping, or bending our body. Frictional Force A force that opposes motion when two surfaces in contact move or tend to move with respect to each other, such as when a ball rolls on the floor and slows down. Mechanical Force A force generated by a machine, such as the engine of a car, that enables it to move on its own. **Non-Contact Force** A force that arises due to interaction between objects that are not in physical contact is called a **non-contact force** or **action at a distance force**. **Type of Non-Contact Force** **Description** ------------------------------- ---------------------------------------------------------------------------------------------------------- Gravitational Force A force of attraction between objects, such as the force of the Sun that keeps planets moving around it. Magnetic Force A force that arises due to the interaction between magnets or magnetic fields. Electrostatic Force A force that arises due to the interaction between charged particles or objects. **Pressure** Pressure is the force exerted per unit area on an object. We will discuss more about pressure and its applications in the next section.\#\# Forces of Nature 🌎 **Gravitational Force** - The force that attracts two objects with mass towards each other. - The Earth\'s gravitational force pulls objects towards its center, which is why objects fall towards the ground. - The moon\'s gravitational force is one-sixth that of the Earth\'s, which is why objects weigh less on the moon. **Magnetic Force** - The force that attracts certain materials, such as iron, towards magnets. - A magnet has two poles, north and south, and opposite poles attract each other while like poles repel. - Magnetic force can be both attractive and repulsive. **Electrostatic Force** - The force that acts between charged bodies, either attractive or repulsive. - Like charges repel each other, while opposite charges attract each other. - There are two types of charges: positive and negative. \"Electrostatic force is a non-contact force that acts between charged bodies.\" **Examples of Forces** **Force** **Description** --------------------- ------------------------------------------------------------- Gravitational Force Attracts objects with mass towards each other Magnetic Force Attracts certain materials towards magnets Electrostatic Force Acts between charged bodies, either attractive or repulsive Muscular Force The force exerted by muscles Mechanical Force The force exerted by machines Frictional Force The force that opposes motion **Action of Two or More Forces** - When two or more forces act on an object, they can be either balanced or unbalanced. - Balanced forces do not change the state of the object, while unbalanced forces do. - The net force acting on an object can be calculated by adding the individual forces. **Pressure 📊** - The force acting normally on a unit area of a surface. - Pressure is calculated by dividing the force by the area over which the force is acting. - The SI unit of pressure is pascal (Pa). \"Pressure is the combined effect of force and area.\" **Factors Affecting Pressure** - The force acting on the surface - The area over which the force is acting **Equation for Pressure** Pressure = Force / Area **Units of Pressure** **Unit** **Description** ------------- -------------------------------------------------- Pascal (Pa) The SI unit of pressure Bar A commonly used unit of pressure, equal to 10 Pa **Know Your Scientist: Blaise Pascal 👨‍🔬** - A French mathematician, physicist, inventor, and writer. - Worked in the field of natural and applied sciences. - Clarified the concepts of vacuum and pressure. - Invented the mechanical calculator.\#\# Pressure 💪 **Definition** Pressure is the force per unit area exerted by an object on another object. **Formula** Pressure (P) = Force (F) / Area (A) P = F / A **Unit** The SI unit of pressure is N/m² or Pa (Pascal). **Characteristics** - Pressure is directly proportional to the force applied on the surface. - Pressure is inversely proportional to the area of contact of a surface. **Applications of Pressure** - We use a sharp knife to cut things rather than a blunt knife because the edge of a sharp knife has a very small area of contact, producing a very large pressure with a small applied force. - Various objects such as board pins, needles, and nails have pointed ends, reducing the area of contact and making it easier for these objects to penetrate the targets. - High-rise buildings have wide foundations to reduce the pressure on the ground. - Wooden/concrete sleepers are used below railway tracks to reduce the pressure exerted by rails on the ground. - School bags have wide straps to increase the surface area of contact and reduce the pressure exerted on the shoulders by the weight of the bag. - Tractors have broad tyres to reduce the pressure on the ground and prevent sinking on soft ground. **Example Problems** **Problem** **Solution** ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ ---------------------------------------------------------- A force of 400 N is applied on an area of 0.02 m². What is the pressure? P = F / A = 400 N / 0.02 m² = 20000 Pa A car has a weight of 15000 N and four tyres. What is the area of contact between the tyre and the road if the pressure between the tyres and the road is 150000 N/m²? Area = Force / Pressure = 3750 N / 150000 N/m² = 0.25 m² **Pressure Exerted by Liquids 💧** **Definition** Liquids exert pressure on the base due to their weight. **Characteristics** - Liquids exert pressure on the walls of the container in which they are kept or enclosed. - Liquid pressure varies with depth. - The pressure exerted at different points at the same depth is equal. **Measurement of Liquid Pressure** - **Method** **Description** ------------ --------------------------------------------------------------------------------------------------------------------------------------- Manometer A U-shaped, transparent glass tube partially filled with water, connected to a rubber tube with a funnel and a stretched rubber film. **Implications of Liquid Pressure** - Deep sea divers need to wear specially designed suits to withstand the enormous liquid pressure at great depth. - In submarines, the hulls have to be specially strengthened to withstand the liquid pressure at great depth. - The bottom of a dam is made thicker than its top to withstand the large liquid pressure at the bottom of a dam. **Pressure Exerted by Gases ⚡️** **Definition** Gases exert pressure on the walls of the container in which they are confined. **Characteristics** - Gases exert pressure on the inner surface of a container, causing it to inflate. - Atmospheric pressure is the force per unit area exerted by the weight of the air. **Atmospheric Pressure** - The atmospheric pressure is maximum at the surface of the earth and decreases as we go to higher altitudes. - Our bodies are well adapted to withstand atmospheric pressure. **Implications of Atmospheric Pressure** - At high altitudes, people may experience a bleeding nose due to the lower external pressure. - Astronauts wear special suits to withstand the extreme conditions of space, including the lack of atmospheric pressure.\#\# Atmospheric Pressure 🌡️ Atmospheric pressure is the **force exerted by the weight of the atmosphere** over a unit area. It is measured by an instrument called a **barometer**. **Factors Affecting Atmospheric Pressure** - **Height**: Atmospheric pressure decreases with an increase in height above sea level. - **Location**: Atmospheric pressure varies with location. **Measuring Atmospheric Pressure** A **barometer** is used to measure atmospheric pressure. The basic principle of the barometer is to use atmospheric pressure to balance a vertical column of **mercury** sealed at the top. **Simple Barometer (Torricelli Barometer)** - Consists of a narrow, thick-glass tube, about one meter long and sealed at one end. - Initially, the tube is completely filled with mercury and is carefully inverted into a trough containing mercury without allowing any air to enter. - The mercury level in the tube drops a little and remains steady at a particular height. - The portion above the mercury column is a **vacuum**, known as the **Torricellian vacuum**. **Units of Atmospheric Pressure** - 1 **atmosphere (atm)**: The pressure equivalent to the 76 cm column of mercury, approximately 1.013 × 10\^5 N/m\^2. **The Magdeburg Experiment** In 1657, Otto von Guericke conducted an experiment to demonstrate the concept of atmospheric pressure. He: - Took two identical metallic hemispheres with smooth edges. - Pumped out the air from inside to create a vacuum. - Eight horses pulled the hemispheres from each side, but they could not separate them, proving the immense pressure exerted by the atmosphere. **Key Concepts** **Concept** **Definition** ----------------- -------------------------------------------------------------- Liquid Pressure Force exerted by a liquid over a unit area. Barometer Instrument used for measuring atmospheric pressure. Manometer Instrument used for measuring liquid pressure. Force A push or a pull that tends to affect an object in some way. \"Pressure is force applied on a surface per unit area.\" **Pressure and Depth** - Pressure increases with **depth** and remains the same at the same **depth**. - Liquids exert the same pressure at the same **depth**. **Characteristics of Pressure** - Pressure is exerted by **liquids** and **gases** in all directions. - The top of a **dam** is made narrower than its bottom to reduce the pressure. **Metals** **Uses of Metals** - Copper and aluminium are used to make electrical wires. - Iron, copper, and aluminium metals are used to make utensils for cooking and manufacturing machine parts. - Iron is used extensively for making magnets and steel is used for the construction of buildings and bridges. Its low cost and high strength makes it indispensable in engineering applications such as the construction of machinery and machine tools. - Lead is used to make paints and car batteries. - Zinc is used for galvanizing iron to protect it from rusting. - Chromium and nickel are used for electroplating various objects and to make stainless steel. - Silver, gold, and platinum are used to make jewelry. - Aluminium finds extensive use in making parts of aeroplanes and spacecrafts. - Mercury is used in thermometers. **Non-Metals** **Uses of Non-Metals** - Nitrogen is used in the manufacturing of fertilizers. Liquid nitrogen is used in various things such as a refrigerant and in medicines. - Phosphorus is used in the match industry and in the manufacturing of fireworks. It is also used to manufacture fertilizers. - Graphite is used for making black lead of pencils. It is used for making electrodes and crucibles for laboratory use. It is also used as a lubricant in machinery and for making fuel rods in nuclear reactors. - Sulphur is used in vulcanization of rubber, which makes rubber hard enough to be used in tyres of vehicles. **Alloys 🔩** - Alloys are mixtures of two or more metals or a metal and a non-metal that have immense applications due to their better characteristics than their individual components. - The arrangement of metals in the order of their decreasing reactivity is called the reactivity series or activity series. **Reactivity Series and Displacement Reaction ⚗️** **Reactivity Series** Reactivity Series: The arrangement of metals in the order of their decreasing reactivity. **Metal** **Reactivity** ----------- ---------------- Potassium Most reactive \... \... Platinum Least reactive **Displacement Reaction** - A more reactive metal displaces a less reactive metal from its salt solution. - These reactions are called displacement reactions. Example: When an iron nail is put in copper sulphate solution, the colour of the solution changes from blue to light green and a reddish-brown coat of copper can be seen on the iron nail. **Reaction with Water and Dilute Acids** **Reaction with Water** - Metals react with water to produce metal oxide (or metal hydroxide) and evolve hydrogen gas. - Metals below hydrogen in the reactivity series do not react with water or dilute acids. **Reaction with Dilute Acids** - Metals react with dilute acids to form a salt with evolution of hydrogen gas. - Some metals such as copper, silver, gold, and platinum do not react with dilute acids. **Metal** **Reaction with Dilute Acid** ----------- ------------------------------- Sodium Reacts Iron Reacts Zinc Reacts Copper Does not react Silver Does not react Gold Does not react Platinum Does not react **Activity: Reaction of a Metal with an Acid** - **Materials**: Steel wool, vinegar, two glass beakers, a sheet of paper (used as a lid), and a thermometer. - **Procedure**: 1. Place the steel wool in a glass beaker. 2. Pour some vinegar in the glass beaker and allow the steel wool to soak in the vinegar for around one minute. 3. Take out the steel wool from the beaker and drain any excess vinegar from it. 4. Wrap the steel wool around the base of the thermometer and place both of them in the second glass beaker. 5. Cover the beaker with the sheet of paper to keep the heat inside the beaker (make sure you can still read the temperature on the thermometer; have a small hole in the paper for the thermometer to go through is a good idea). 6. Check the initial temperature on the thermometer and then monitor it for around five minutes. **Reaction of Non-Metals with Oxygen** - Non-metals such as carbon, sulphur, and phosphorus, burn in the presence of oxygen to form their corresponding oxides. **Non-Metal** **Reaction with Oxygen** --------------- -------------------------- Carbon Forms carbon dioxide Sulphur Forms sulphur dioxide Phosphorus Forms phosphorus oxide **Reaction of Non-Metals with Water** - Non-metals do not generally react with water. - Oxygen dissolves in water in very less amount, which ensures the sustenance of aquatic living organisms as their lives depend on the oxygen which dissolved in water. - Chlorine, another non-metal, dissolves in water to form an acidic solution.\#\# Corrosion and Rusting 💔 Corrosion is the process where a metal gets eaten away due to a chemical reaction in the presence of atmospheric gases and moisture. Iron metal is slowly oxidized to produce rust (iron oxide) in the presence of moist air. 4Fe + 3O2 → 2Fe3O4 Fe3O4 + nH2O → Fe3O4.nH2O (Rust) Similarly, copper articles develop a greenish coating of basic copper carbonate on exposure to air. 2Cu + O2 + CO2 + H2O → Cu(OH)2.CO3 (Basic Copper Carbonate) **Chemical Properties of Metals and Non-Metals ⚗️** **Reaction with Oxygen** Metals combine with oxygen to form metal oxides. The general equation for the formation of metal oxides is: Metal + Oxygen → Metal Oxide Different metals have different reactivities towards oxygen. They react with oxygen at different temperatures. **Examples:** - Sodium (Na) and potassium (K) are highly reactive metals that burn in the presence of air and form their corresponding oxides at room temperature. - Magnesium metal burns with a white dazzling flame in the presence of air and forms magnesium oxide. - Mg + O2 → 2MgO - Zinc metal reacts with air only on strong heating to form zinc oxide. - 2Zn + O2 → 2ZnO **Metal Oxides** Metal oxides are basic in nature because when dissolved in water, they form metal hydroxides, which turn red litmus blue. **Examples:** - Sodium oxide (NaO) dissolves in water to form sodium hydroxide (NaOH). - NaO + H2O → 2NaOH - Potassium oxide (KO) dissolves in water to form potassium hydroxide (KOH). - KO + H2O → 2KOH **Physical Properties of Metals and Non-Metals 🔍** **Physical State** **Category** **Physical State at Room Temperature** -------------- --------------------------------------------------------------------------------- Metals Solid (except Mercury, which is liquid) Non-Metals Solid (sulphur, phosphorus), Gas (oxygen, nitrogen, chlorine), Liquid (Bromine) **Strength** **Category** **Strength** -------------- ------------------------------------------------------------------------------------------ Metals Strong and hard (aluminium, iron, copper, lead), Soft and easily cut (sodium, potassium) Non-Metals Not as strong as metals, but Diamond is the hardest natural substance **Lustre** Lustre refers to the shiny appearance of metals. **Examples:** - Metals like gold and silver have a shiny appearance and are used in jewelry and decoration. - Non-metals have a dull surface, but graphite, diamond, and iodine are exceptions. **Malleability** Malleability is the property by which metals can be beaten into sheets. **Examples:** - Almost every metal shows malleability, with gold being the most malleable. - Non-metals are brittle and break into pieces when hammered. **Conductivity** **Category** **Conductivity** -------------- -------------------------------------------------------------------------------------------------- Metals Good conductors of heat and electricity Non-Metals Bad conductors of heat and electricity, except Graphite which is a good conductor of electricity **Occurrence in Nature 🌎** **Metals** - Almost all metals are found in the Earth\'s crust. - The most abundant metal present in the Earth\'s crust is Aluminium. - Metals occur in nature in different forms: - Free state (e.g., Gold, Silver, Platinum) - Combined state (e.g., Potassium, Sodium, Calcium) **Non-Metals** - Non-metals are some of the most abundant elements present in the universe. - Examples: Hydrogen, Carbon, Sulphur, Oxygen, Chlorine, and Nitrogen. - Non-metals occur in nature in different forms: - Free state (e.g., Noble gases like Helium, Neon, Argon) - Combined state (e.g., Hydrogen and Oxygen in water) **Metalloids** Metalloids are elements that have some properties of metals and non-metals. **Examples:** - Boron, Silicon, Tellurium, Germanium, Arsenic, and Antimony. - The most abundant metalloid present on the Earth is Silicon, which is found as silica (combined with oxygen) in rocks, sand, clay, and soil.\#\# Classification of Elements 🌟 Elements are classified into three categories based on their properties: **Metals**, **Non-Metals**, and **Metalloids**. **Physical Properties of Metals and Non-Metals** - **Metals**: - Have high melting and boiling points - Are good conductors of heat and electricity - Are malleable and ductile - Are shiny and lustrous - **Non-Metals**: - Have low melting and boiling points - Are poor conductors of heat and electricity - Are brittle and non-malleable - Are dull and non-lustrous **Chemical Properties of Metals and Non-Metals** - **Reactions with Air**: Metals react with air to form oxides, while non-metals do not react with air. - **Reactions with Water**: Metals react with water to form hydroxides, while non-metals do not react with water. - **Reactions with Acids**: Metals react with acids to form salts and hydrogen gas, while non-metals do not react with acids. **Uses of Metals** - **Alloys**: A mixture of two or more metals or metals and non-metals. - **Examples of Alloys**: **Alloy** **Composition** **Uses** ----------------- ------------------------------------------------ ----------------------------------------------------------------------------------- Brass 65% Copper, 35% Zinc Musical instruments, utensils, electrical fittings Bronze 88% Copper, 12% Tin Gears, machine bearings, statues, control valves Solder 63% Tin, 37% Lead Joining electrical wires Stainless Steel 74% Iron, 18% Chromium, 8% Nickel Cutlery, tools, household utensils, shaving blades, watch cases, automobile parts Magnalium 68-95% Aluminium, 5-30% Magnesium, 1-2% Copper Mirrors, scientific instruments Duralumin 95% Aluminium, 4% Copper Light weight instruments and aircraft bodies **Non-Metal Examples** - **Graphite**: Used for making electrodes and crucibles for laboratory use, and for making black lead of pencils. - **Phosphorus**: Used in the match industry and in the manufacturing of fireworks. - **Sulphur**: Used in vulcanizing rubber. - **Copper and Aluminium**: Used to make electrical wires. - **Lead**: Used to make paints. - **Silicon**: Used in thermometers. - **Nitrogen**: Used in the manufacturing of fertilizers. - **Gold**: Not used to make machine tools due to its high cost and low strength.