Basic Chemistry Concepts: Elements, Atoms, Bonds, and Reactions

Element

Unique substance that cannot be broken down into simpler substances by ordinary chemical methods

Atom

Indescribably small clusters of subatomic particles (protons, neutrons, electrons); building blocks of matter

Isotope

Elements with the same number of protons and electrons but different numbers of neutrons; same atomic number, different atomic mass

Ion

An atom with a positive or negative electric charge due to gaining or losing electrons

Subatomic Particles

Smaller particles that make up an atom: protons, neutrons, electrons

Compound

Substance composed of two or more different elements chemically united

Ionic Bond

Bond formed when electrons are completely transferred from one atom to another

Covalent Bond

Bond formed when atoms share valence electrons

Hydrogen Bond

Extremely weak bond where a hydrogen atom forms a bridge between two electronegative atoms (like N or O)

Hydrolysis Reaction

Process in which water is used to split a substance into smaller particles

Synthesis Reaction

Reaction where two or more atoms or molecules combine to form a larger, more complex molecule (A+B=AB); energy-storing

Universal Solvent

Water; can dissolve more substances than any other liquid

Simple Carbohydrates

Monosaccharides (single sugar molecules), building blocks of complex carbs like disaccharides and polysaccharides

Amino Acids

Molecules that combine to form proteins; building blocks of life

Nucleic Acids DNA & RNA

Organic molecules made of nucleotides (sugar, phosphate, nitrogen base); DNA stores genetic code, RNA converts it into proteins

ATP

Adenosine triphosphate; energy currency of cells; hydrolysis of ATP releases energy (ATP → ADP + phosphate + energy)

Polar Compounds

Molecules with uneven electron distribution, creating positive and negative regions; e.g., H2O, NH3, HCl, SO2

Non-polar Compounds

Molecules with even electron distribution and no overall charge; generally insoluble in water; e.g., fats, oils, noble gases