Basic Concepts in Chemistry

Atoms: Basic units of matter made up of protons, neutrons, and electrons.
Elements: Pure substances consisting of only one type of atom; represented on the periodic table.
Compounds: Substances formed when two or more elements chemically bond together.

Nucleus: Central part of an atom, containing protons (positive charge) and neutrons (no charge).
Electrons: Negatively charged particles that orbit the nucleus in electron shells.
Atomic Number: Number of protons in the nucleus; defines the element.
Mass Number: Total number of protons and neutrons in the nucleus.

Ionic Bonds: Formed when electrons are transferred from one atom to another, creating ions.
Covalent Bonds: Formed when two atoms share electrons.
Metallic Bonds: Characterized by a ‘sea of electrons’ shared among a lattice of metal atoms.

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

Reactants: Substances that undergo change in a chemical reaction.
Products: Substances formed as a result of a chemical 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: An element replaces another in a compound.
- Double Replacement: Exchange of ions between two compounds.
- Combustion: Reaction with oxygen producing heat and light, often yields carbon dioxide and water.

Acids: Substances that donate protons (H+) and have a pH less than 7.
Bases: Substances that accept protons and have a pH greater than 7.
pH Scale: Measures the acidity or alkalinity of a solution, ranges from 0 to 14.

Groups/Families: Vertical columns, elements have similar chemical properties (e.g., alkali metals, halogens).
Periods: Horizontal rows, represent energy levels of electrons.
Metals, Nonmetals, Metalloids: Distinct categories based on physical and chemical properties.

Mole: Quantity of substance containing Avogadro's number (6.022 x 10²³) of particles.
Molar Mass: Mass of one mole of a substance, expressed in grams.
Balancing Equations: Ensures the number of atoms of each element is the same on both sides of a chemical equation.

Hydrocarbons: Compounds composed mainly of hydrogen and carbon.
Functional Groups: Specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules (e.g., hydroxyl, carboxyl).

Conservation of Mass: Mass is neither created nor destroyed in a chemical reaction.
Law of Definite Proportions: A chemical compound always contains its constituent elements in fixed ratio by mass.
Reaction Rates: Influenced by concentration, temperature, catalysts, and surface area.

Atoms are the fundamental building blocks of matter. They consist of protons, neutrons, and electrons.
Elements are pure substances composed of only one type of atom, organized on the periodic table.
Compounds are formed when two or more elements chemically bond together.

The nucleus is the central part of an atom, containing positively charged protons and neutral neutrons.
Electrons are negatively charged particles that orbit the nucleus in electron shells.
The atomic number defines the element and represents the number of protons in the nucleus.
The mass number represents the total number of protons and neutrons in an atom's nucleus.

Ionic bonds form when electrons are transferred from one atom to another, resulting in the formation of ions.
Covalent bonds form when two atoms share electrons.
Metallic bonds involve a "sea of electrons" shared among a lattice of metal atoms.

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

Reactants are the substances that undergo change during a chemical reaction.
Products are the substances formed as a result of a chemical 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: Ions are exchanged between two compounds.
- Combustion: A reaction involving oxygen, often releasing heat and light, which usually produces carbon dioxide and water.

Acids donate protons (H+), resulting in a pH less than 7.
Bases accept protons, leading to a pH greater than 7.
The pH scale measures the acidity or alkalinity of a solution, ranging from 0 to 14.

Groups/Families (vertical columns) contain elements with similar chemical properties, such as alkali metals and halogens.
Periods (horizontal rows) represent the energy levels of electrons.
Metals, Nonmetals, Metalloids are distinct categories based on their physical and chemical properties.

Mole is the quantity of a substance containing Avogadro's number (6.022 x 10²³) of particles.
Molar Mass is the mass of one mole of a substance, expressed in grams.
Balancing Equations ensures that the number of atoms of each element is the same on both sides of a chemical equation.

Hydrocarbons are compounds primarily composed of hydrogen and carbon.
Functional Groups are specific groups of atoms within molecules that determine their characteristic chemical reactions (e.g., hydroxyl, carboxyl).

Conservation of Mass: Mass is neither created nor destroyed in a chemical reaction.
Law of Definite Proportions: A chemical compound always contains its constituent elements in a fixed ratio by mass.
Reaction Rates can be influenced by factors like concentration, temperature, catalysts, and surface area.