Basic Concepts of Chemistry

Matter: Anything that has mass and occupies space. Divided into:
- Elements: Pure substances made of one type of atom (e.g., oxygen, gold).
- Compounds: Substances formed from two or more elements chemically bonded (e.g., water, carbon dioxide).
Atoms: The basic unit of matter, consisting of:
- Nucleus: Contains protons (positive charge) and neutrons (no charge).
- Electrons: Negatively charged particles orbiting the nucleus in electron shells.
Chemical Bonds:
- Ionic Bonds: Formed when electrons are transferred from one atom to another (e.g., sodium chloride).
- Covalent Bonds: Formed when atoms share electrons (e.g., hydrogen gas).
- Metallic Bonds: Involves the pooling of electrons among a lattice of metal atoms.

Solid: Definite shape and volume; particles packed closely together.
Liquid: Definite volume but takes the shape of its container; particles less tightly packed.
Gas: No definite shape or volume; particles are far apart and move freely.

Reactants: Substances that undergo a chemical change.
Products: New substances formed as a result of a chemical reaction.
Types of Reactions:
- Synthesis: Two or more substances combine to form a new compound (A + B → AB).
- Decomposition: A compound breaks down into simpler substances (AB → A + B).
- Single Replacement: One element replaces another in a compound (A + BC → AC + B).
- Double Replacement: Exchange of ions between two compounds (AB + CD → AD + CB).

Balancing Equations: Law of conservation of mass states that matter cannot be created or destroyed. Ensure the same number of each type of atom on both sides.
Reactants and products: Generally written as:
- Reactants → Products

Acids: Substances that donate protons (H⁺ ions) in an aqueous solution.
Bases: Substances that accept protons or donate hydroxide ions (OH⁻).
pH Scale: Measures acidity/alkalinity of a solution (0-14 scale).
- pH < 7: Acidic
- pH = 7: Neutral
- pH > 7: Basic

Arrangement:
- Rows (Periods): Indicate a new energy level of electrons.
- Columns (Groups): Elements in the same group have similar chemical properties.
Key Groups:
- Alkali Metals (Group 1): Highly reactive, soft metals.
- Alkaline Earth Metals (Group 2): Reactive metals with higher melting points than alkali metals.
- Noble Gases (Group 18): Inert gases with complete electron shells.

Titration: Method to determine the concentration of a solution by reacting it with a reagent of known concentration.
Filtration: Process of separating solids from liquids using a porous material.
Chromatography: Technique for separating mixtures based on differences in movement through a medium.

Stoichiometry: The calculation of reactants and products in chemical reactions.
Thermodynamics: Study of energy changes during chemical reactions.
Kinetics: Study of the rate of chemical reactions and the factors that affect them.

Matter is anything with mass and occupies space.
Elements are pure substances made of one type of atom (e.g., oxygen, gold).
Compounds are substances formed from two or more elements chemically bonded (e.g., water, carbon dioxide).
Atoms are the basic unit of matter with a nucleus containing protons (positive charge) and neutrons (no charge) and electrons (negatively charged particles) orbiting the nucleus in shells.
Ionic bonds form by electron transfer between atoms (e.g., sodium chloride).
Covalent bonds form when atoms share electrons (e.g., hydrogen gas).
Metallic bonds involve the pooling of electrons among a lattice of metal atoms.

Solids have a definite shape and volume, with particles packed closely together.
Liquids have a definite volume but take the shape of their container, particles are less tightly packed.
Gases have no definite shape or volume with particles far apart and moving freely.

Reactants are substances that undergo change in a chemical reaction.
Products are new substances formed from a chemical reaction.
Synthesis reactions involve two or more substances combining to form one new compound (A + B → AB)
Decomposition reactions involve one compound breaking down into simpler substances (AB → A + B).
Single replacement reactions involve one element replacing another in a compound (A + BC → AC + B).
Double replacement reactions involve an exchange of ions between two compounds (AB + CD → AD + CB).

Balancing chemical equations ensures the same number of each type of atom on both sides to follow the law of conservation of mass (matter cannot be created or destroyed).
Reactants and products are generally written as: Reactants → Products

The periodic table arranges elements in rows (periods), indicating a new energy level of electrons, and columns (groups) representing elements with similar chemical properties.
Alkali Metals (Group 1) are highly reactive, soft metals.
Alkaline Earth Metals (Group 2) are reactive metals with higher melting points than alkali metals.
Noble Gases (Group 18) are inert gases with full electron shells.

Titration determines the concentration of a solution by reacting it with a known concentration reagent.
Filtration separates solids from liquids using porous materials.
Chromatography separates a mixture based on differences in movement through a medium.

Stoichiometry is the calculation of reactants and products in chemical reactions.
Thermodynamics studies energy changes during chemical reactions.
Kinetics studies the rate of chemical reactions and factors affecting them.