Chemistry Chapter on Atoms and Bonds

Atoms and Subatomic Particles

• Atoms are the smallest units of matter, consisting of a nucleus (protons and neutrons) and an electron cloud.
• Subatomic particles include protons, neutrons, and electrons.

Elements and Compounds

• Elements are pure substances made of one type of atom, identified by symbols (e.g., H for hydrogen).
• Compounds are formed from two or more atoms of different elements.

Isotopes and Ions

• Isotopes vary in neutron number within the same element.
• Ions are atoms or molecules with a net charge due to the gain or loss of electrons.

Chemical Bonds

• Chemical bonds are the forces that join atoms together.
• Covalent bonds involve the sharing of electrons between atoms.
• Ionic bonds form through the attraction of oppositely charged ions.
• Hydrogen bonds are weak attractions between polar molecules.

Water and Its Properties

• Water constitutes about 70% of the human body and has unique properties such as high heat capacity.
• Cohesion refers to the attraction between similar substances, while adhesion is the attraction between different substances.
• Surface tension is a result of cohesive forces that allow small objects to float on water.

Solutions and Solubility

• A solution is a mixture where substances are evenly distributed.
• Polar molecules, such as water, dissolve well in water, whereas nonpolar molecules do not (e.g., oils).

Acids, Bases, and pH

• Acids release hydrogen ions (H+) in solutions, while bases reduce H+ concentration and increase hydroxide ions (OH-).
• The pH scale measures hydrogen ion concentration, ranging from 0 to 14 (acidic: 0-6, neutral: 7, basic: 8-14).

Carbohydrates

• Carbohydrates are organic compounds (C, H, O in 1:2:1 ratio) essential for energy, including monosaccharides (simple sugars), disaccharides (double sugars), and polysaccharides (starch, glycogen, cellulose).

Lipids and Fats

• Lipids are nonpolar molecules important for cell membrane structure; they include saturated fats (solid at room temperature) and unsaturated fats (liquid at room temperature).

Proteins

• Proteins consist of amino acids and serve various functions in organisms.
• Enzymes, a type of protein, speed up chemical reactions and are influenced by temperature and pH.

Nucleic Acids

• Nucleic acids (DNA and RNA) are long chains of nucleotides that store genetic information and perform various roles in cellular processes.
• DNA is double-stranded while RNA is single-stranded and assists in protein synthesis.

Energy in Biological Systems

• Energy is stored in chemical bonds (e.g., carbohydrates) and is essential for cellular functions.
• ATP is the primary energy currency in cells, derived from glucose metabolism.

Chemical Reactions and Metabolism

• Chemical reactions involve breaking and forming bonds to create new substances, categorized into reactants (starting materials) and products (newly formed substances).
• Metabolism encompasses all chemical processes within an organism, influenced by factors such as activation energy and enzyme activity.

Enzymes and Catalysts

• Enzymes lower the activation energy required for reactions, making them essential catalysts.
• Each enzyme is specific to its substrate, fitting into a unique active site.

Temperature and pH for Enzymatic Activity

• Enzymes generally function best at around 37 degrees Celsius (body temperature).
• Common enzymes include catalase (breaks down hydrogen peroxide) and amylase (breaks down starch).

Additional Concepts

• Collagen and hemoglobin are vital proteins in the body.
• The pH of common substances illustrates acid-base properties, e.g., vinegar (pH 3-4) and household ammonia (pH 12).