Basic Concepts of Chemistry

Matter: Anything that has mass and occupies space; classified into elements, compounds, and mixtures.
Element: A pure substance that cannot be broken down into simpler substances; represented by symbols (e.g., H for Hydrogen).
Compound: A substance formed when two or more elements chemically combine (e.g., H2O for water).
Mixture: A combination of two or more substances that retain their individual properties (e.g., saltwater).

Solid: Fixed shape and volume; particles closely packed.
Liquid: Fixed volume but takes the shape of its container; particles are close but can move.
Gas: No fixed shape or volume; particles are far apart and move freely.
Plasma: Ionized gas with free-moving ions and electrons; occurs at high temperatures.

Ionic Bonds: Formed between oppositely charged ions; typically between metals and non-metals (e.g., NaCl).
Covalent Bonds: Formed when two atoms share electrons; typically between non-metals (e.g., CO2).
Metallic Bonds: Alloys of metals; electrons are delocalized and move freely, contributing to conductivity.

Reactants and Products: Reactants are substances that undergo change; products are formed as a result.
Types of Reactions:
1. Synthesis: Two or more reactants combine to form one product (A + B → AB).
2. Decomposition: A single compound breaks down into two or more products (AB → A + B).
3. Single Replacement: An element replaces another in a compound (A + BC → AC + B).
4. Double Replacement: Exchange of ions between two compounds (AB + CD → AD + CB).
5. Combustion: A substance reacts with oxygen, usually producing heat and light (typically involves hydrocarbons).

Mole Concept: A mole is 6.022 x 10²³ particles (Avogadro's number); used to quantify elements and compounds.
Molar Mass: The mass of one mole of a substance (g/mol); calculated by summing the atomic masses of its constituent atoms.

Acids: Substances that donate protons (H⁺) in solution; characterized by a sour taste and pH < 7 (e.g., HCl).
Bases: Substances that accept protons or donate hydroxide ions (OH⁻); characterized by a bitter taste and pH > 7 (e.g., NaOH).
pH Scale: Measures acidity or basicity, ranging from 0 (acidic) to 14 (basic), with 7 being neutral.

Endothermic Reactions: Absorb heat from surroundings (e.g., photosynthesis).
Exothermic Reactions: Release heat into surroundings (e.g., combustion).
Enthalpy (H): Measures heat content; changes during reactions can be calculated (ΔH).

Solution: Homogeneous mixture of a solute dissolved in a solvent.
Concentration: Measure of solute in a given volume of solution; commonly expressed in molarity (M).

Groups: Vertical columns; elements have similar chemical properties (e.g., alkali metals, halogens).
Periods: Horizontal rows; properties change progressively across a period.
Metals, Nonmetals, Metalloids: Metals are typically good conductors; nonmetals are poor conductors; metalloids have properties of both.

Hydrocarbons: Compounds made exclusively of carbon and hydrogen; can be aliphatic or aromatic.
Functional Groups: Specific groups of atoms that affect molecular behavior (e.g., -OH for alcohols, -COOH for carboxylic acids).

These notes cover foundational knowledge in chemistry and can aid in further studies and understanding in various branches of the field.

Matter is anything that occupies space and has mass.
It can be categorized into elements, compounds, and mixtures.
Elements are pure substances that cannot be broken down further. They are represented by symbols like 'H' for Hydrogen.
Compounds are formed when two or more elements chemically combine (e.g., water, H₂O).
Mixtures are combinations where individual substances retain their properties (e.g., saltwater).

Solid: Has a fixed shape and volume; particles are closely packed.
Liquid: Has a fixed volume but takes the shape of its container; particles are close but can move.
Gas: Doesn't have a fixed shape or volume; particles are far apart and move freely.
Plasma: Ionized gas with free-moving ions and electrons, present at high temperatures.

Ionic Bonds: Formed between oppositely charged ions, typically between metals and nonmetals (e.g., NaCl, table salt).
Covalent Bonds: Formed when atoms share electrons, commonly between nonmetals (e.g., CO₂, carbon dioxide).
Metallic Bonds: Occur in alloys of metals, where electrons are delocalized and move freely, contributing to conductivity.

Reactants are substances that undergo change in a chemical reaction.
Products are the substances formed as a result of the reaction.
Types of Reactions:
- Synthesis: Two or more reactants combine to form one product (A + B → AB).
- Decomposition: A single compound breaks down into two or more products (AB → A + B).
- Single Replacement: An element replaces another in a compound (A + BC → AC + B).
- Double Replacement: Exchange of ions between two compounds (AB + CD → AD + CB).
- Combustion: A substance reacts with oxygen, often producing heat and light (common in hydrocarbons).

Mole Concept: A mole represents 6.022 x 10²³ particles (Avogadro's number). It is used to quantify substances.
Molar Mass: The mass of one mole of a substance (measured in g/mol). It is calculated by adding the atomic masses of its constituent atoms.

Acids: Substances that donate protons (H⁺) in solution. They have a sour taste and a pH value below 7 (e.g., HCl, hydrochloric acid).
Bases: Substances that accept protons or donate hydroxide ions (OH⁻). They have a bitter taste and a pH above 7 (e.g., NaOH, sodium hydroxide).
pH Scale: Measures the acidity or basicity of a solution, ranging from 0 (acidic) to 14 (basic), with 7 being neutral.

Endothermic Reactions: Absorb heat from their surroundings (e.g., photosynthesis).
Exothermic Reactions: Release heat into their surroundings (e.g., combustion).
Enthalpy (H): Measures heat content. Changes in enthalpy during reactions are represented by ΔH.

Solution: A homogeneous mixture of a solute dissolved in a solvent.
Concentration: The measure of solute present in a given volume of solution. It is commonly expressed in molarity (M).

Groups: Vertical columns in the periodic table. Elements in the same group share similar chemical properties (e.g., alkali metals, halogens).
Periods: Horizontal rows in the periodic table. Properties change progressively across a period.
Metals, Nonmetals, Metalloids: Metals are generally good conductors of electricity and heat. Nonmetals are poor conductors. Metalloids have properties of both metals and nonmetals.

Hydrocarbons: Compounds composed only of carbon and hydrogen. They can be aliphatic or aromatic.
Functional Groups: Specific groups of atoms that influence the behavior of a molecule (e.g., -OH for alcohols, -COOH for carboxylic acids).