Chemistry is often referred to as the “central science” because it connects other sciences like biology, physics, and environmental science. Its applications extend far beyond laboratories, impacting daily life, industry, medicine, agriculture, and more. Let’s explore the importance of chemistry in different spheres of life:
1. Medicine and Healthcare:
- Drug Formulation: Chemistry is essential in the development of pharmaceuticals. Medicines like antibiotics, painkillers, and vaccines are developed using chemical processes.
- Diagnostic Tools: Chemistry contributes to the creation of diagnostic tools like X-rays, MRI contrast agents, and blood test kits.
2. Agriculture and Food:
- Fertilizers and Pesticides: Chemistry helps in the production of fertilizers that increase crop yield and pesticides that protect crops from pests.
- Food Preservation: Chemical preservatives, food additives, and packaging techniques ensure longer shelf life and safety of food products.
3. Environment:
- Pollution Control: Chemistry provides solutions for monitoring and controlling pollution, such as catalytic converters in cars and wastewater treatment processes.
- Green Chemistry: This branch focuses on developing eco-friendly chemicals and processes that minimize environmental harm.
4. Household Products:
- Cleaning Agents: Soaps, detergents, and disinfectants are all products of chemical formulations.
- Cosmetics and Personal Care: Shampoos, lotions, and perfumes are developed using knowledge of chemistry to ensure safety and effectiveness.
5. Industry and Technology:
- Material Science: Chemistry helps develop new materials like polymers, alloys, and nanomaterials used in everything from clothing to electronics.
- Energy Production: Chemistry is central to battery technology, fuel cells, and renewable energy solutions like solar panels.
Classification of Substances into Elements, Compounds, and Mixtures
All matter around us can be classified into elements, compounds, or mixtures based on their composition and the nature of their components.
1. Elements:
- Definition: An element is a pure substance that consists of only one type of atom. It cannot be broken down into simpler substances by chemical means.
- Examples: Hydrogen (H), Oxygen (O), Gold (Au), Silver (Ag).
- Types of Elements:
- Metals: Iron (Fe), Copper (Cu).
- Non-metals: Carbon (C), Sulfur (S).
- Metalloids: Silicon (Si), Boron (B).
2. Compounds:
- Definition: A compound is a pure substance composed of two or more elements that are chemically combined in a fixed proportion. Compounds have properties different from their constituent elements.
- Examples: Water (H₂O), Carbon dioxide (CO₂), Sodium chloride (NaCl).
- Types of Compounds:
- Organic Compounds: Methane (CH₄), Glucose (C₆H₁₂O₆).
- Inorganic Compounds: Sodium hydroxide (NaOH), Ammonia (NH₃).
3. Mixtures:
- Definition: A mixture is a combination of two or more substances (elements or compounds) that are physically mixed but not chemically combined. The components retain their individual properties and can be separated by physical means.
- Examples: Air (mixture of gases), Saltwater (mixture of salt and water), Alloys (mixture of metals like brass).
- Types of Mixtures:
- Homogeneous Mixtures: Mixtures that are uniform throughout, like salt dissolved in water.
- Heterogeneous Mixtures: Mixtures that have visibly different components, like oil and water or sand and iron filings.
Here’s the classification of each substance into elements, compounds, or mixtures based on chemical classification:
- Sugar: Compound
- Sugar (like sucrose) is a compound composed of carbon, hydrogen, and oxygen chemically bonded in a fixed proportion.
- Sea Water: Mixture
- Sea water is a mixture of various salts, water, and other dissolved substances. It is not chemically bonded in a fixed ratio.
- Distilled Water: Compound
- Distilled water (pure H₂O) is a compound made up of hydrogen and oxygen chemically combined in a fixed ratio.
- Carbon Dioxide: Compound
- Carbon dioxide (CO₂) is a compound where carbon and oxygen are chemically bonded in a fixed ratio.
- Copper Wire: Element
- Copper wire is made of the element copper (Cu), which consists of only one type of atom.
- Table Salt: Compound
- Table salt (sodium chloride, NaCl) is a compound made of sodium and chlorine chemically bonded in a fixed ratio.
- Silver Plate: Element
- A silver plate is made of the element silver (Ag), consisting of only one type of atom.
- Naphthalene Balls: Compound
- Naphthalene (C₁₀H₈) is a compound consisting of carbon and hydrogen atoms chemically bonded in a fixed proportion.
In Short
- Elements: Copper wire, Silver plate.
- Compounds: Sugar, Distilled water, Carbon dioxide, Table salt, Naphthalene balls.
- Mixtures: Sea water.
Illustration of Classification:
- Element: Copper wire is made up of only copper atoms.
- Element : An element consists of only one type of atom. We know that an atom is the smallest electrically neutral particle, being made up of fundamental particles, namely electrons, protons and neutrons. Element can exist as monatomic or polyatomic units. Example : Monatomic unit – Gold (Au), Copper (Cu); Polyatomic unit – Hydrogen (H2), Phosphorous (P4) and Sulphur (S8
- Compound: Water is made of hydrogen and oxygen atoms chemically combined in a fixed ratio (H₂O).
- Mixture: Sea water contains salts, water, and other dissolved substances mixed together without chemical bonding.
Atomic Mass and Molecular Mass
Understanding atomic and molecular masses is fundamental in chemistry, as these concepts are used to quantify the amounts of substances involved in reactions.
1. Atomic Mass:
- Definition: The atomic mass of an element is the weighted average mass of all the naturally occurring isotopes of that element, expressed in atomic mass units (amu).
- Atomic Mass Unit (amu): 1 amu is defined as one-twelfth the mass of a carbon-12 atom.
- Example: The atomic mass of hydrogen is approximately 1.008 amu.
2. Molecular Mass:
- Definition: The molecular mass of a compound is the sum of the atomic masses of all the atoms in a molecule of that compound.
- Calculation: Molecular mass is calculated by adding the atomic masses of the constituent elements in their respective proportions.
- Example:
- Water (H₂O):
- Hydrogen (H): 1.008 amu × 2 = 2.016 amu
- Oxygen (O): 16.00 amu
- Molecular Mass of Water = 2.016 + 16.00 = 18.016 amu
Importance of Atomic and Molecular Mass:
- Atomic and molecular masses are used in chemical equations, stoichiometry, and to determine the relative amounts of reactants and products in chemical reactions.