Introduction to Chemistry

The study of matter, its properties, composition, structure, and changes it undergoes during chemical reactions.

Inorganic Chemistry
- Focuses on inorganic compounds (minerals, metals).
Organic Chemistry
- Deals with carbon-containing compounds and their reactions.
Physical Chemistry
- Examines the physical properties and behavior of chemical systems.
Analytical Chemistry
- Involves techniques to analyze substances and determine their composition.
Biochemistry
- Studies the chemical processes within and related to living organisms.

Solid: Definite shape and volume; particles are closely packed.
Liquid: Definite volume but takes the shape of the container; particles are close but can move.
Gas: No definite shape or volume; particles are far apart and move freely.
Plasma: Ionized gas with free electrons; conducts electricity and is affected by magnetic fields.

Atoms: Basic units of matter composed of protons, neutrons, and electrons.
- Protons: Positive charge, found in the nucleus.
- Neutrons: No charge, found in the nucleus.
- Electrons: Negative charge, orbit around the nucleus.

Ionic Bonds
- Formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions.
Covalent Bonds
- Involve the sharing of electron pairs between atoms.
Metallic Bonds
- Characterized by a 'sea of electrons' shared among a lattice of metal cations.

Reactants: Substances that undergo a chemical change.
Products: Substances formed as a result of the reaction.
Types of Reactions:
- Synthesis: Two or more substances combine to form a new compound.
- Decomposition: A compound breaks down into simpler substances.
- Single Replacement: One element replaces another in a compound.
- Double Replacement: Exchange of ions between two compounds.
- Combustion: Reaction with oxygen producing energy, carbon dioxide, and water.

Law of Conservation of Mass: Mass is neither created nor destroyed in a chemical reaction.
Law of Definite Proportions: A chemical compound contains the same elements in the same proportions by mass, regardless of the sample size.
Law of Multiple Proportions: When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in a ratio of small whole numbers.

Mole: A unit representing 6.022 x 10²³ entities (atoms, molecules, ions).
Molar Mass: Mass of one mole of a substance, typically expressed in grams per mole (g/mol).

Acids: Substances that donate protons (H⁺ ions) in a solution.
Bases: Substances that accept protons or donate hydroxide ions (OH⁻).
pH Scale: Measures the acidity or basicity of a solution (scale of 0-14); pH < 7 is acidic, pH = 7 is neutral, pH > 7 is basic.

Chemistry is the study of matter, including its properties, composition, structure, and changes during chemical reactions.

Inorganic Chemistry: Concentrates on inorganic compounds like minerals and metals.
Organic Chemistry: Focuses on carbon-based compounds and their reactions.
Physical Chemistry: Investigates the physical properties and behaviors of chemical systems.
Analytical Chemistry: Uses techniques to analyze substances and determine their compositions.
Biochemistry: Examines chemical processes in living organisms.

Solid: Has a definite shape and volume; particles are tightly packed.
Liquid: Has a definite volume but adapts to the shape of its container; particles are close yet can move.
Gas: Lacks a defined shape or volume; particles are widely spaced and move freely.
Plasma: A form of ionized gas with free electrons; it can conduct electricity and is influenced by magnetic fields.

Atoms: The fundamental units of matter made up of protons, neutrons, and electrons.
Protons: Positively charged particles located in the nucleus of the atom.
Neutrons: Neutral particles also found in the nucleus.
Electrons: Negatively charged particles that orbit around the nucleus.

Elements: Arranged by atomic number and grouped based on similar chemical properties.
Groups: Vertical columns that categorize elements with similar characteristics (e.g., alkali metals, halogens).
Periods: Horizontal rows in the table indicating a progression in properties.

Ionic Bonds: Formed through the transfer of electrons, resulting in oppositely charged ions.
Covalent Bonds: Involve the sharing of electron pairs between atoms.
Metallic Bonds: Characterized by a collective sharing of electrons among a grid of metal cations.

Reactants: Substances that undergo changes during a chemical reaction.
Products: New substances formed as a result of the reaction.
Types of Reactions:
- Synthesis: Combination of two or more substances to create a new compound.
- Decomposition: Breakdown of a compound into simpler substances.
- Single Replacement: An element takes the place of another in a compound.
- Double Replacement: An exchange of ions occurs between two compounds.
- Combustion: A reaction with oxygen that yields energy, carbon dioxide, and water.

Law of Conservation of Mass: Mass remains constant; it cannot be created or destroyed in a reaction.
Law of Definite Proportions: A chemical compound always contains the same elements in the same mass proportions.
Law of Multiple Proportions: When forming multiple compounds, the mass ratios of elements are small whole numbers.

Mole: Represents 6.022 x 10²³ entities (atoms, molecules, ions).
Molar Mass: The mass of one mole of a substance, expressed in grams per mole (g/mol).

Acids: Substances that donate protons (H⁺ ions) in solutions.
Bases: Substances that can accept protons or donate hydroxide ions (OH⁻).
pH Scale: Ranges from 0 to 14 to indicate acidity or basicity; pH < 7 is acidic, pH = 7 is neutral, pH > 7 is basic.