Basic Concepts of Chemistry

Matter: Anything that has mass and occupies space.
Elements: Pure substances made of only one type of atom (e.g., hydrogen, oxygen).
Compounds: Substances formed from two or more elements chemically bonded (e.g., water, CO2).

Atoms: Basic units of matter composed of protons, neutrons, and electrons.
- Protons: Positively charged particles in the nucleus.
- Neutrons: Neutral particles in the nucleus.
- Electrons: Negatively charged particles orbiting the nucleus.
Atomic Number: Number of protons in an atom; defines the element.
Mass Number: Total number of protons and neutrons.

Ionic Bonds: Formed by the transfer of electrons from one atom to another (e.g., NaCl).
Covalent Bonds: Formed by the sharing of electrons between atoms (e.g., H2O).
Metallic Bonds: Formed by the pooling of electrons among a lattice of metal atoms.

Solid: Definite shape and volume; particles are tightly packed.
Liquid: Definite volume but no definite shape; particles are close but can move past each other.
Gas: No definite shape or volume; particles are far apart and move freely.

Reactants: Substances that undergo change in a reaction.
Products: Substances formed as a result of a 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: An element replaces another in a compound (A + BC → AC + B).
- Double Replacement: Exchange of ions between two compounds (AB + CD → AD + CB).

Acids: Substances that donate protons (H+) in solution (e.g., HCl).
Bases: Substances that accept protons or donate hydroxide ions (OH-) (e.g., NaOH).
pH Scale: Measures the acidity or basicity of a solution (0-14 scale; 7 is neutral).

Endothermic Reactions: Absorb heat from the surroundings (e.g., photosynthesis).
Exothermic Reactions: Release heat to the surroundings (e.g., combustion).

Solvent: Substance that dissolves the solute (e.g., water).
Solute: Substance that is dissolved (e.g., salt).
Concentration: Amount of solute in a given volume of solvent, commonly expressed in molarity (M).

Hydrocarbons: Compounds consisting primarily of hydrogen and carbon.
Functional Groups: Specific groups of atoms that impart characteristic properties (e.g., hydroxyl -OH, carboxyl -COOH).
Isomers: Compounds with the same molecular formula but different structures.

Titration: Analytical method to determine concentration of a solution.
Chromatography: Technique for separating mixtures based on differential affinities.
Spectroscopy: Technique for analyzing materials based on their interaction with light.

Matter consists of anything with mass and occupies space.
Elements are pure substances containing only one type of atom, such as hydrogen and oxygen.
Compounds result from the chemical bonding of two or more elements, exemplified by water (H2O) and carbon dioxide (CO2).

Atoms are the fundamental units of matter, made up of protons, neutrons, and electrons.
Protons carry a positive charge and reside in the nucleus of an atom.
Neutrons are neutral and also located in the nucleus.
Electrons carry a negative charge and orbit the nucleus in defined energy levels.
The atomic number indicates the number of protons in an atom, uniquely defining each element.
The mass number is the sum of an atom's protons and neutrons.

Ionic bonds occur when electrons are transferred between atoms, resulting in charged ions (e.g., sodium chloride, NaCl).
Covalent bonds form when atoms share electrons, as seen in water (H2O).
Metallic bonds involve a delocalized pooling of electrons among a lattice of metal atoms.

Solids have a fixed shape and volume, with tightly packed particles.
Liquids maintain a constant volume but take the shape of their container, with more mobile particles.
Gases lack both definite shape and volume; particles are widely spaced and move freely.

Reactants are the initial substances that undergo transformation during a reaction.
Products are the substances that result from the reaction.
Types of chemical reactions include:
- Synthesis: Combining substances to form a new compound (e.g., A + B → AB).
- Decomposition: Breaking down a compound into simpler components (e.g., AB → A + B).
- Single Replacement: An element swaps with another in a compound (e.g., A + BC → AC + B).
- Double Replacement: Exchange of ions between two compounds (e.g., AB + CD → AD + CB).

Acids give off protons (H+) in solution, such as hydrochloric acid (HCl).
Bases accept protons or release hydroxide ions (OH-), like sodium hydroxide (NaOH).
The pH scale ranges from 0 to 14; 7 indicates neutrality, below 7 is acidic, and above 7 is basic.

Endothermic reactions absorb heat from their surroundings, demonstrated in processes like photosynthesis.
Exothermic reactions release heat, occurring during combustion.

Groups (families) are the vertical columns that encompass elements with similar characteristics.
Periods are horizontal rows reflecting energy levels of electrons in the elements.
Elements are categorized as metals, nonmetals, or metalloids based on their properties.

A solvent is the medium that dissolves a solute (e.g., water dissolving salt).
A solute is the substance that is dissolved.
Concentration represents the amount of solute in a given volume of solvent, often measured in molarity (M).

Hydrocarbons are compounds made up chiefly of hydrogen and carbon atoms.
Functional groups determine the specific chemical properties of organic molecules (e.g., hydroxyl -OH, carboxyl -COOH).
Isomers are compounds that share the same molecular formula but differ in structural arrangement.

Titration is a method used to determine the concentration of a solution quantitatively.
Chromatography separates mixtures into their components based on their varying affinities.
Spectroscopy analyzes materials by studying their interaction with light to determine composition.