Key Concepts in Chemistry

Matter: Anything that has mass and occupies space.
Element: A pure substance that cannot be broken down into simpler substances; composed of atoms.
Compound: A substance formed when two or more elements chemically bond together.
Mixture: A combination of two or more substances that are not chemically bonded.

Atom: The smallest unit of an element, consisting of protons, neutrons, and electrons.
- Proton: Positively charged particle in the nucleus.
- Neutron: Neutral particle in the nucleus.
- Electron: Negatively charged particle that orbits the nucleus.
Atomic Number: The number of protons in an atom's nucleus; defines the element.
Mass Number: The total number of protons and neutrons in an atom's nucleus.

Groups: Vertical columns; elements within the same group have similar chemical properties (e.g., Group 1: Alkali metals).
Periods: Horizontal rows; properties change progressively across a period.

Ionic Bond: Transfer of electrons from one atom to another, resulting in attraction between oppositely charged ions.
Covalent Bond: Sharing of electrons between atoms to achieve stable electron configurations.
Metallic Bond: Attraction between metal ions and delocalized electrons, allowing for conductivity and malleability.

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

Reactants: Substances that undergo change during a reaction.
Products: New 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 energy, water, and carbon dioxide.

Acid: Substance that donates protons (H+) in solution; pH < 7.
Base: Substance that accepts protons or donates hydroxide ions (OH-); pH > 7.
pH Scale: Measures acidity/basicity; ranges from 0 to 14.

Molar Mass: Mass of one mole of a substance, expressed in grams per mole (g/mol).
Mole: A quantity of substance containing 6.022 x 10²³ particles (Avogadro's number).
Balancing Equations: Ensuring that the number of atoms for each element is the same on both sides of a chemical equation.

Thermodynamics: Study of energy changes in physical and chemical processes.
Kinetics: Study of the rates of chemical reactions.
Equilibrium: The state in which the concentrations of reactants and products remain constant over time.
Redox Reactions: Types of reactions involving the transfer of electrons between species.

Personal Protective Equipment (PPE): Safety goggles, gloves, lab coats.
Proper Disposal: Follow guidelines for disposing of chemicals safely.
Knowledge of Material Safety Data Sheets (MSDS): Key information on handling, hazards, and safety precautions for chemicals.

Matter: Anything that has mass and takes up space.
Element: A pure substance that cannot be broken down into simpler substances. It is composed of only one type of atom.
Compound: A substance formed when two or more elements are chemically bonded together.
Mixture: A combination of two or more substances that are not chemically bonded.

Atom: The smallest unit of an element, consisting of a nucleus surrounded by electrons.
Proton: A positively charged particle found in the nucleus.
Neutron: A neutrally charged particle found in the nucleus.
Electron: A negatively charged particle that orbits the nucleus.
Atomic Number: The number of protons in an atom's nucleus, determining its element.
Mass Number: The total number of protons and neutrons in an atom's nucleus.

Groups: Vertical columns in the periodic table. Elements in the same group share similar chemical properties.
Periods: Horizontal rows in the periodic table. Element properties change progressively across a period.

Ionic Bond: A bond formed by the transfer of electrons from one atom to another resulting in the attraction between oppositely charged ions.
Covalent Bond: A bond formed by the sharing of electrons between atoms to achieve stable electron configurations.
Metallic Bond: A bond formed by the attraction between metal ions and delocalized electrons, leading to conductivity and malleability.

Solid: Has a definite shape and volume due to tightly packed particles.
Liquid: Has a definite volume but no definite shape due to particles close together but able to flow.
Gas: Has no definite shape or volume due to particles far apart and moving freely.

Reactants: The substances that undergo change during a chemical reaction.
Products: The new 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: A rapid reaction with oxygen producing energy, water, and carbon dioxide.

Acid: A substance that donates protons (H+) in solution, having a pH less than 7.
Base: A substance that accepts protons or donates hydroxide ions (OH-), having a pH greater than 7.
pH Scale: A measure of acidity/basicity ranging from 0 to 14, with 7 being neutral.

Molar Mass: The mass of one mole of a substance expressed in grams per mole (g/mol).
Mole: A quantity of substance containing 6.022 x 10²³ particles (Avogadro's number).
Balancing Equations: Ensuring the number of atoms of each element is the same on both sides of a chemical equation.

Exothermic Reaction: A reaction that releases energy into the surroundings, usually as heat, making the surroundings warmer.
Endothermic Reaction: A reaction that absorbs energy from the surroundings, usually as heat, making the surroundings colder.

Thermodynamics: The study of energy changes in physical and chemical processes.
Kinetics: The study of the rates of chemical reactions.
Equilibrium: A state in which the concentrations of reactants and products remain constant over time.
Redox Reactions: Reactions involving the transfer of electrons between species.

Personal Protective Equipment (PPE): Safety goggles, gloves, lab coats to protect from potential hazards.
Proper Disposal: Following guidelines for safely disposing of chemicals.
Knowledge of Material Safety Data Sheets (MSDS): Understanding key information on handling, hazards, and safety precautions for chemicals.