The Chemical Basis of Life

Atomic Structure and Electrons

• Atomic number refers to the number of protons in the nucleus of an atom, determining the element's identity.
• Mass number is the total number of protons and neutrons in an atom’s nucleus.
• Valence electrons are the outermost electrons involved in chemical bonding and reactions.
• Silicon (Si) and carbon (C) are examples of elements with 4 valence electrons.
• Carbon is the most abundant element in living organisms, essential for life's molecular structures.

Subatomic Particles

• Protons have a positive charge and are located in the nucleus.
• Neutrons are electrically neutral and also found in the nucleus.
• Electrons have negligible mass relative to protons and neutrons, found in orbitals outside the nucleus.

Chemical Bonds and Reactions

• Covalent bonds involve the sharing of electron pairs between atoms.
• Ionic bonds involve the complete transfer of electrons from one atom to another.
• Covalent bonds are generally the strongest type of chemical bond.
• Chemical potential energy is stored in the bonds linking atoms to form molecules.
• Adenosine triphosphate (ATP) is the primary energy currency for cells.

Energy and Metabolism

• Exothermic reactions release energy during the process.
• Increasing temperature and concentration are two methods to accelerate reaction rates.
• Metabolism encompasses the entirety of biochemical processes occurring within a living organism.

Water Properties

• Energy and matter primarily enter the biosphere through photosynthesis and nutrient cycling.
• Water's polarity allows it to dissolve polar and charged molecules, acting as a solvent.
• Ice floats due to its lower density compared to liquid water.
• Cohesion leads to the formation of a meniscus when water meets a solid surface.
• Surface tension prevents light objects from sinking in water due to cohesive forces among water molecules.
• Capillary action enables water to travel in biological systems, such as within plant roots and leaves.

pH and Cellular Response

• pH measures the concentration of H+ and OH- ions in a solution, affecting biological and chemical processes.
• Buffers help cells maintain stable pH levels, protecting against damaging fluctuations in acidity or alkalinity.

Organic Chemistry

• The functional behavior of a molecule in organic chemistry is determined by its structure and functional groups.
• Amino acids are the building blocks of proteins, linked by peptide bonds.
• Carbon's tetravalency allows it to form diverse molecular shapes and combinations of bonds.
• Water's high specific heat capacity allows it to absorb and retain substantial amounts of energy, regulating temperature in environments.

Test your knowledge of the chemical basis of life with this quiz on water and carbon. Learn about the key elements that make up living things and their roles in structure and function. Explore the properties of matter and understand the significance of protons, neutrons, and electrons.