Basic Concepts of Chemistry

Matter: Anything that has mass and occupies space.
Atoms: Basic units of matter; consist of protons, neutrons, and electrons.
Elements: Pure substances made of only one type of atom; represented by symbols (e.g., H for hydrogen).
Compounds: Substances formed from two or more elements chemically bonded together (e.g., H₂O for water).

Organization: Elements are arranged by increasing atomic number and grouped by similar properties.
Groups: Vertical columns; elements in the same group exhibit similar chemical behaviors.
Periods: Horizontal rows; indicate the number of electron shells.

Ionic Bonds: Formed when electrons are transferred from one atom to another, resulting in charged ions.
Covalent Bonds: Formed when atoms share electrons.
Metallic Bonds: Involve the sharing of free electrons among a lattice of metal ions.

Reactants and Products: Substances consumed (reactants) and produced (products) during a 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 heat and light, often resulting in CO₂ and H₂O.

Solid: Defined shape and volume; particles are tightly packed.
Liquid: Defined volume, no fixed shape; particles are close but can move past one another.
Gas: No fixed shape or volume; particles are far apart and move freely.
Plasma: Ionized gas with free-moving ions and electrons, found in stars including the sun.

Solution: A homogeneous mixture of solute and solvent (e.g., salt in water).
Solubility: The ability of a solute to dissolve in a solvent at a given temperature.
Concentration: Amount of solute present in a given volume of solution.

Acids: Substances that donate protons (H⁺) in solution; have a pH less than 7.
Bases: Substances that accept protons or donate hydroxide ions (OH⁻); have a pH greater than 7.
pH Scale: Measures acidity or basicity of a solution, ranging from 0 (strong acid) to 14 (strong base).

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

Reaction Rate: Speed at which reactants change into products; affected by concentration, temperature, and surface area.
Chemical Equilibrium: State in which the forward and reverse reaction rates are equal, resulting in constant concentrations of reactants and products.

Matter is anything that has mass and occupies space.
The basic unit of matter is the atom, which is made up of protons, neutrons, and electrons.
Elements are pure substances made of only one type of atom and are represented by chemical symbols.
Compounds are formed when two or more elements chemically bond together.

The periodic table organizes elements by increasing atomic number.
Elements in the same vertical column, called a group, have similar chemical properties.
Elements in the same horizontal row, called a period, have the same number of electron shells.

Ionic bonds form when electrons are transferred between atoms, resulting in the formation of charged ions.
Covalent bonds form when atoms share electrons.
Metallic bonds involve the sharing of free electrons among a lattice of metal ions.

Matter exists in different states:
- Solids have a fixed shape and volume, and their particles are tightly packed.
- Liquids have a fixed volume but no fixed shape, and their particles are close but can move past each other.
- Gases have no fixed shape or volume, and their particles are far apart and move freely.
- Plasma is an ionized gas with free-moving ions and electrons, found in stars like the Sun.

A solution is a homogeneous mixture of a solute and a solvent.
Solubility refers to the ability of a solute to dissolve in a solvent at a given temperature.
Concentration measures the amount of solute present in a given volume of solution.

Acids donate protons (H⁺) in solution and have a pH less than 7.
Bases accept protons or donate hydroxide ions (OH⁻) in solution and have a pH greater than 7.
The pH scale measures the acidity or basicity of a solution, ranging from 0 (strong acid) to 14 (strong base).

The reaction rate measures the speed at which reactants are converted into products.
The reaction rate is affected by factors such as concentration, temperature, and surface area.
Chemical equilibrium occurs when the forward and reverse reaction rates are equal, resulting in constant concentrations of reactants and products.