HLTH1004 W2 L2.2.1

Atoms and Atomic Structure

• Definition of Matter: Anything that occupies space and has mass (made of atoms)

  • Atoms join together to form chemicals with different characteristics

  • chemical characteristics determine physiology at molecular and cellular levels

• Composition of Atoms: Consist of subatomic particles - protons, neutrons, and electrons

• Role of Electrons: Participate in chemical bonding

Subatomic Particles

• Nucleus: Contains protons (positively charged) and neutrons (neutral); contributes to mass

• Electrons: Negatively charged, represented as an electron cloud due to uncertainty in their position; low mass significance

• Atomic Number: Determined by the number of protons; organizes elements in the periodic table

  • Atomic number = no. of protons

Periodic Table of Elements

• Dmitri Mendeleev's Contribution: First organized the periodic table in 1869 based on atomic number

• Groupings in the Periodic Table:

  • Group 1 (vertical): Alkaline metals (except hydrogen)

  • Transition Metals: Unique properties based on environmental factors

  • Group 18: Noble gases - stable with full outer electron shells, non-reactive

Example: Carbon

• Position: Group 14

• Atomic Number: 6 (6 protons)

• Symbol: C

• Atomic Weight: Approximately 12 mass units

  • Characteristics: Weakly acidic, hexagonal crystalline structure, nonmetal

• Importance: Among the six most abundant elements in the body

Abundant Elements in Body

• Major Components of Body Mass (99%): Oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus

• Minor Components (~0.85%): Potassium, sulphur, sodium, chlorine, and magnesium

Definitions

• Element: A substance composed of only one type of atom

• Atomic Weight: Average weight of an element in atomic mass

• Mole: Grams equivalent to the atomic weight of the element

• Isotopes: Variants of elements differing in mass number, can be stable or unstable (radioisotopes)

• Half-Life: Time required for half the quantity of a radioactive isotope to decay

Significance of Chemistry in Physiology

• Understanding atomic structure and interaction aids in grasping molecular and cellular physiology

• Chemical reactions, facilitated by water and regulated by pH and buffers, are essential for bodily function