Atoms consist of a nucleus of protons and neutrons surrounded by electrons arranged in energy levels, and an atom's chemical behavior is governed by the number and arrangement of valence electrons. Chemical bonding — covalent bonds (electron sharing), ionic bonds (electron transfer between oppositely charged ions), and weaker interactions such as hydrogen bonds and van der Waals forces — determines how atoms combine into molecules, while pH quantifies the concentration of hydrogen ions in solution on a logarithmic scale, governing acid-base chemistry that underlies biological reactions. These are foundational principles of general and biological chemistry, forming the basis for understanding molecular structure and reactivity in living systems.
Atoms consist of a nucleus of protons and neutrons surrounded by electrons arranged in energy levels, and an atom's chemical behavior is governed by the number and arrangement of valence electrons. C…