Chapter 2: Chemistry of Life

Matter

Anything that occupies space and has mass.

Atom

The smallest unit of matter, used to build more complicated substances.

Molecules

Particles of matter composed of one or more atoms, the basic unit of matter.

Protons

Subatomic particles occurring in all atomic nuclei, with a positive electric charge.

Neutrons

Subatomic particles with a neutral electric charge and slightly more mass than protons.

Electrons

Negatively charged particles that orbit the nucleus of an atom.

Atomic Number

The number of protons in the nucleus of an atom.

Atomic Mass

The combined number of protons and neutrons in an atom.

Element

A pure substance consisting of only one type of atom, characterized by its atomic number.

Compound

Substances formed when two or more different elements chemically bond in fixed ratios.

Ionic Bond

A bond formed between atoms where one atom donates electrons to another to fill outer shells.

Covalent Bond

A bond formed when atoms share electrons to achieve a full outer shell, resulting in a stable molecule.

Hydrogen Bond

A weak attraction that helps hold substances together, forming structures in the body.

Isotopes

Atoms of the same element with the same atomic number but different atomic masses.

Radioactive Isotope

Isotope that emits radiation and may damage cells.

Electrolytes

Compounds that form ions when dissolved in water.

Dehydration Synthesis

A chemical reaction that involves the loss of water to bond smaller molecules into larger ones.

Hydrolysis

A chemical reaction that involves the addition of water to break down larger molecules.

Acid

Substances that release H+ ions in solution, typically with a pH less than 7.

Base

Substances that accept H+ ions in solution, usually with a pH greater than 7.

pH Scale

A measure of how acidic or basic a solution is, ranging from 0 to 14.

Buffer

Chemicals in the blood that help maintain pH balance.

Carbohydrates

Organic compounds composed of carbon and water, serving as energy sources.

Lipids

Molecules that do not usually dissolve in water, crucial for energy storage and cell membrane structure.

Proteins

Composed of amino acids; essential for body structure and function.

Nucleic Acid

Molecules that store genetic information, such as DNA and RNA.

Double Helix

The twisted structure of DNA, consisting of two strands of nucleotides.

ATP

A molecule that transfers energy within cells for various functions.