Units of Measurement, Atomic Structure, and Electron Configuration

Overview of Units in Measurement

  • Importance of understanding both derived and base units in nursing and other sciences.

Base Units

  • Definition:
    • Base units are the fundamental units of measurement from which all other derived units are obtained.
  • Examples of Base Units:
    • Length: Meter (m)
    • Time: Second (s)
    • Mass: Kilogram (kg)
    • Temperature: Kelvin (K)
    • Electric Current: Ampere (A)
    • Amount of Substance: Mole (mol)
    • Luminous Intensity: Candela (cd)
  • Total: There are seven base units recognized as International System of Units (SI units).

Derived Units

  • Definition:
    • Derived units are units that are calculated from base units.
  • Examples of Derived Units:
    • Area: Square Meter (m²)
    • Example Calculation: Area = Meter × Meter = Meter².
    • Volume: Cubic Meter (m³)
    • Density: Kilogram per Cubic Meter (kg/m³)
    • Example: Kg is derived from mass, and m³ from volume (length).
    • Force: Newton (N)
    • Example: N = kg × (m/s²) = kg·m/s².
    • Explanation: Newton is considered a derived unit because it is formed from base units.

Conversion of Units

  • Temperature Conversions:
    • Kelvin and Celsius Relationship:
    • K = °C + 273.15
    • To convert from Celsius to Kelvin:
    • Add 273.15 to the Celsius temperature.
    • To convert from Kelvin to Celsius:
    • Subtract 273.15 from the Kelvin temperature.
  • Example Calculation:
    • Converting 100°C to K:
    • 100°C + 273.15 = 373.15 K
    • Converting 1000 K to °C:
    • 1000 K - 273.15 = 726.85°C

Understanding Metric Prefixes

  • Kilo (k) = 10³, representing a thousand units.
  • Purpose: Understanding these prefixes aids in measuring various scientific quantities accurately.

Atomic Structure

  • Introduction to Atom: Atoms are the fundamental building blocks of matter, composed of particles.

Historical Background

  • Key Scientists:
    • Leucippus and Democritus: Proposed the concept of indivisible particles called atoms (Greek word: "atomos").
    • John Dalton: First to propose the idea of atoms as small indivisible particles that participate in chemical reactions.

Definitions Related to Atoms

  • Atom: The smallest unit of an element that retains the properties of that element.

Key Postulates of Dalton's Atomic Theory

  • Matter is composed of small indivisible particles.
  • Atoms of a given element are identical in their properties.
  • Compounds are formed when atoms of different elements combine in fixed ratios.
  • Chemical reactions involve the rearrangement of atoms; they are neither created nor destroyed.

Structure of Atom

  • Components of Atom:
    • Nucleus: Contains protons (positively charged) and neutrons (neutral).
    • Electrons: Negatively charged particles that orbit the nucleus.
    • The number of electrons is equal to the number of protons in a neutral atom.

Models of the Atom

  • JJ Thompson's Plum Pudding Model: Describes atom as spheres of positive charge with negatively charged electrons embedded within.
  • Rutherford's Nuclear Model: Proposes a dense center (nucleus) surrounded by orbiting electrons.
  • Bohr Model: Electrons move in fixed orbits around the nucleus.

Mass Number Calculation

  • Mass Number (A): Sum of protons and neutrons in the nucleus.
  • Formula:
    • A = Z + N
    • Where A = mass number, Z = atomic (proton) number, N = neutron number.

Electron Configuration

  • Arrangement of electrons in shells around the nucleus is defined as electronic configuration.
  • Shell Number: Indicates the energy level; subshells are designated as s, p, d, f based on shape and capacity.
    • Shell 1: 1s
    • Shell 2: 2s, 2p
    • Shell 3: 3s, 3p, 3d
    • Shell 4: 4s, 4p, 4d, 4f

Filling Order of Electrons

  • Rule: Electrons fill the lowest energy orbitals first (Aufbau Principle).
  • Maximum capacities are:
    • s = 2
    • p = 6
    • d = 10
    • f = 14

Shell Capacity Calculation Formula

  • E = 2n²
    • Where E = maximum number of electrons in a shell, n = shell number.
    • Example: For third shell (n=3), max electrons = 2(3²) = 18.

Summary of Relationships

  • Atomic Number = Number of Protons = Number of Electrons.
  • Mass Number = Number of Protons + Number of Neutrons.
  • Electrons occupy shells arranged according to their energy levels.

Final Notes

  • It’s crucial to memorize both unit conversions and the basic structure of the atom to facilitate understanding in various scientific fields.
  • These notes cover a comprehensive overview of measurement units and atomic structure which are fundamental in nursing and related sciences. They provide a solid foundation for more advanced topics and practical applications in the field.