Matter

Definition and States of Matter

Matter is anything that has mass and occupies space. It is the fundamental substance of the universe and forms the basis for all physical objects, including those in the human body.

• Three States of Matter: Solid, liquid, and gas.

• Chemistry: The study of matter and its interactions.

Atoms and Atomic Structure

Properties and Structure of Atoms

An atom is the smallest unit of matter that retains the properties of an element. Atoms are composed of subatomic particles and are the building blocks of all substances.

• Subatomic Particles:

  • Protons (p+): Found in the nucleus, positively charged.

  • Neutrons (n): Found in the nucleus, no charge.

  • Electrons (e-): Found in electron shells surrounding the nucleus, negatively charged.

• Electron Shells: Regions around the nucleus where electrons exist.

  • First shell: Can hold 2 electrons.

  • Second shell: Can hold 8 electrons.

  • Third shell: Can hold 18 electrons (with additional info: shells fill in order of increasing energy).

Elements in the Periodic Table and the Human Body

Elements and Atomic Number

Elements are pure substances that cannot be broken down by chemical means. Each element is defined by its atomic number, which is the number of protons in its nucleus.

• Periodic Table: Lists elements by atomic number and organizes them into groups with similar properties.

• Chemical Symbol: Each element is represented by a unique symbol.

• Major Elements in the Human Body:

  • Oxygen (O)

  • Carbon (C)

  • Hydrogen (H)

  • Nitrogen (N)

Isotopes and Radioactivity

Isotopes and Atomic Mass

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, resulting in different mass numbers. Some isotopes are radioactive and can emit energy.

• Atomic Mass: Equal to the sum of all protons and neutrons in the nucleus.

• Radioactive Isotopes: Unstable isotopes that emit radiation as they decay.

Mixtures

Types of Mixtures

Mixtures are combinations of two or more substances that are physically blended but not chemically bonded.

• Solution: Homogeneous mixture where particles are evenly distributed.

• Solvent: Substance that dissolves another substance.

• Solute: Substance that is dissolved.

Chemical Bonds

Types of Chemical Bonds

Chemical bonds are forces that hold atoms together in molecules and compounds. They are essential for the structure and function of biological molecules.

• Ionic Bonds: Formed when electrons are transferred from a metal atom to a nonmetal atom, resulting in the formation of cations (positive ions) and anions (negative ions).

• Covalent Bonds: Formed when two nonmetals share electrons.

  • Single bond: One pair of shared electrons.

  • Double bond: Two pairs of shared electrons.

  • Triple bond: Three pairs of shared electrons.

• Hydrogen Bonds: Weak attractions between partially positive and partially negative ends of molecules, important for the properties of water.

Chemical Notation

Representing Chemical Reactions

Chemical notation is used to represent chemical reactions, showing the transformation of reactants into products.

• Reactants: Substances that undergo change, written on the left side of the equation.

• Products: Substances formed, written on the right side of the equation.

• Arrow (→): Indicates the direction of the reaction.

Energy and Chemical Reactions

Forms of Energy

Energy is the capacity to do work. In biological systems, energy is required for chemical reactions and cellular processes.

• Potential Energy: Stored energy due to position or structure.

• Kinetic Energy: Energy of motion.

Types of Chemical Reactions

Chemical reactions in the body are essential for metabolism and homeostasis.

• Decomposition Reactions: Large substances are broken down into smaller substances.

• Synthesis Reactions: Small subunits are combined to make larger, more complex substances.

• Exchange Reactions: Atoms are exchanged between reactants.

Water

Properties of Water

Water is vital for life and is the most abundant molecule in the human body. It is a polar molecule, allowing it to dissolve many substances.

• Hydrophilic: "Water-loving" substances that dissolve in water.

• Hydrophobic: "Water-fearing" substances that do not dissolve in water, such as oils and fats.

Acids and Bases

pH and Buffer Systems

Acids and bases are important for maintaining the body's pH balance. The pH scale measures the concentration of hydrogen ions in a solution.

• Acid: Substance that releases hydrogen ions () in solution.

• Base: Substance that removes hydrogen ions or releases hydroxide ions ().

• pH Scale: Ranges from 0 (most acidic) to 14 (most basic).

• Buffer: Chemical system that resists changes in pH.

Monomers and Polymers

Biological Macromolecules

Macromolecules in the body are built from smaller units called monomers. Polymers are chains of monomers linked by chemical bonds.

• Hydrolysis: Catabolic reaction that uses water to break up polymers into smaller subunits.

Carbohydrates

Structure and Function

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They serve primarily as a source of fuel for the body.

• Monosaccharides: Simple sugars (e.g., glucose).

• Polysaccharides: Complex carbohydrates (e.g., starch, glycogen).

Lipids

Types and Functions

Lipids are a group of nonpolar hydrophobic molecules composed mainly of carbon and hydrogen. They include fats, oils, and steroids.

• Fatty Acids: Building blocks of lipids.

• Saturated Fats: Solid at room temperature, no double bonds between carbon atoms.

• Unsaturated Fats: Liquid at room temperature, have one or more double bonds between carbon atoms.

Proteins

Structure and Roles

Proteins are polymers made of amino acids. They play diverse roles in the body, including structural support, catalysis, and regulation.

• Enzymes: Proteins that catalyze chemical reactions.

• Building Blocks: Amino acids.

Nucleotides and Nucleic Acids

DNA and RNA Structure

Nucleic acids are polymers of nucleotides and are essential for genetic information storage and transfer.

• DNA: Contains the bases adenine (A), guanine (G), cytosine (C), and thymine (T).

• RNA: Contains the bases adenine (A), guanine (G), cytosine (C), and uracil (U) (instead of thymine).

• Function: DNA stores genetic information; RNA is involved in protein synthesis.

Genetic Information Flow

• Transcription: DNA is used as a template to make RNA.

• Translation: RNA directs the synthesis of proteins.

Summary Table: Major Elements in the Human Body

Summary Table: Types of Chemical Bonds

Summary Table: pH Scale

Additional info: Some explanations and examples have been expanded for clarity and completeness, based on standard Anatomy & Physiology curriculum.