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 when two or more elements chemically bond (e.g., H2O).

Solid: Definite shape and volume; particles are closely packed.
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.

Ionic Bonds: Formed through the transfer of electrons from one atom to another, creating charged ions.
Covalent Bonds: Formed when two atoms share one or more pairs of electrons.
Metallic Bonds: Involves the sharing of free electrons among a lattice of metal atoms.

Reactants: Substances that undergo a change in a chemical reaction.
Products: New substances formed as a result of a chemical reaction.
Types of Reactions:
- Synthesis: Combining elements to form compounds.
- Decomposition: Breaking down compounds 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 and often heat and light.

Elements are organized by:
- Atomic number (number of protons)
- Chemical properties
- Groups (columns) and periods (rows)
Key Groups:
- Alkali Metals (Group 1): Highly reactive metals.
- Alkaline Earth Metals (Group 2): Reactive metals, less so than alkali metals.
- Transition Metals: Elements in the center of the table; good conductors of heat and electricity.
- Halogens (Group 17): Reactive nonmetals.
- Noble Gases (Group 18): Inert gases, low reactivity.

Acids: Substances that donate protons (H+ ions) 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 the acidity or basicity of a solution from 0 (acidic) to 14 (basic).

Mole Concept: A mole represents 6.022 x 10²³ particles (Avogadro's number).
Balanced Chemical Equations: Ensure the same number of each type of atom on both sides of a reaction.
Molar Mass: The mass of one mole of a substance, calculated from its atomic mass.

Hydrocarbons: Compounds made of hydrogen and carbon; include alkanes, alkenes, and alkynes.
Functional Groups: Specific groups of atoms that impart characteristic properties to organic compounds (e.g., -OH for alcohols, -COOH for carboxylic acids).

Law of Conservation of Mass: Mass is neither created nor destroyed in a chemical reaction.
Law of Definite Proportions: A chemical compound always contains the same proportion of elements by mass.
Law of Multiple Proportions: When two elements form more than one compound, the ratios of the masses of the second element that combine with a fixed mass of the first element are simple whole numbers.

Matter is defined as anything that possesses mass and occupies space.
Atoms are the fundamental units of matter, composed of protons, neutrons, and electrons.
Elements are pure substances consisting of only one type of atom, represented by symbols such as H for hydrogen.
Compounds are formed when two or more elements chemically bond, exemplified by water (H₂O).

Solids have a definite shape and volume, with closely packed particles.
Liquids have a definite volume but adapt to the shape of their container, featuring less tightly packed particles.
Gases lack both definite shape and volume, with particles that are widely spaced and can move freely.

Ionic bonds result from the transfer of electrons between atoms, generating charged ions.
Covalent bonds are formed when pairs of electrons are shared between two atoms.
Metallic bonds involve a lattice structure where free electrons are shared among metal atoms.

Elements on the periodic table are categorized by atomic number, chemical properties, groups (columns), and periods (rows).
Alkali Metals (Group 1) are characterized as highly reactive metals.
Alkaline Earth Metals (Group 2) are also reactive but less so than alkali metals.
Transition Metals are located in the center of the table and are known for their good conductivity of heat and electricity.
Halogens (Group 17) are reactive nonmetals.
Noble Gases (Group 18) are inert gases that exhibit low reactivity.

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

A mole is defined as 6.022 x 10²³ particles, known as Avogadro's number.
Balanced chemical equations maintain the same number of each atom type on both sides of the reaction.
Molar mass is the mass of one mole of a substance, identified through its atomic mass.

Exothermic reactions release energy, typically in the form of heat, to the environment.
Endothermic reactions absorb energy from the surroundings.

Hydrocarbons are compounds consisting of hydrogen and carbon, including categories such as alkanes, alkenes, and alkynes.
Functional Groups are specific atom groups that provide unique properties to organic compounds, for example, -OH in alcohols and -COOH in carboxylic acids.

The Law of Conservation of Mass states that mass is neither created nor destroyed in chemical reactions.
The Law of Definite Proportions indicates that a compound consistently contains the same proportion of elements by mass.
The Law of Multiple Proportions asserts that in different compounds formed by the same elements, the mass ratios of one element combining with a fixed mass of the other are simple whole numbers.