Agusan del Sur State College of Agriculture and Technology
College of Teacher Education
Department of Science Education
ACTIVITY 1: TRACING
THE ORIGIN OF AN ATOM
S118: Modern Physics
Chapter 1: Structure of Atoms
Submitted by:
KEVIN PAUL PARAGUA DEAÑO
BSED Science 3B, Student
Submitted to:
ELLIE ACEBIDO CANGGO
S118 Reporter
Activity 1: Tracing the Origin of an Atom
Atoms are the fundamental building blocks of matter, consisting of a nucleus composed
of protons and neutrons, surrounded by electrons. The concept of atoms dates back to ancient
civilizations, such as Greek philosophers like Democritus, who proposed the idea of indivisible
particles called "atomos." However, it wasn't until the late 19th and early 20th centuries that
experimental evidence, such as the discovery of the electron by J.J. Thomson and the nuclear
model of the atom by Ernest Rutherford, solidified the atomic theory. This theory revolutionized
our understanding of matter and laid the foundation for modern chemistry and physics.
John Dalton (1803)
John Dalton's atomic theory proposed in the early 19th century
suggested that all matter is composed of indivisible particles
called atoms, which are identical within an element but vary
between elements. He also suggested that chemical reactions
involve the rearrangement of these atoms, with no creation or
Solid Sphere destruction of atoms. This theory laid the foundation for
Model modern chemistry by providing a systematic explanation for the
composition and behavior of matter.
J. J. Thomson (1904)
J.J. Thomson's atomic theory, developed in the late 19th
century, introduced the concept of the electron and
revolutionized the understanding of atomic structure. Thomson
proposed that atoms are not indivisible, as Dalton suggested,
but rather composed of smaller particles. He discovered the
Plum Pudding electron through his experiments with cathode rays, suggesting
Model that atoms contain negatively charged electrons embedded
within a positively charged sphere, like "plums" embedded in a
positively charged "pudding." This model, known as the "plum
Ernest pudding
Rutherford (1911)contributed to the understanding of atomic
model,"
structure and laid the
Ernest Rutherford's groundwork
atomic for further
theory, developed in discoveries in
the early 20th
particle
century, physics.
refined our understanding of atomic structure. Through
his famous gold foil experiment, Rutherford discovered that
atoms have a small, dense nucleus at their center, which
contains positively charged protons. He proposed that most of
the atom's mass and positive charge are concentrated in this
nucleus, while electrons orbit around it at a distance. This
model, known as the nuclear model of the atom, replaced J.J.
Thomson's plum pudding model and laid the foundation for
modern atomic theory, providing a more accurate picture of
atomic structure.
Nuclear Model
Niels Bohr (1913)
Niels Bohr's atomic theory, developed in the early 20th century,
expanded upon Ernest Rutherford's nuclear model of the atom.
Bohr proposed that electrons orbit the nucleus in specific
energy levels or orbits, rather than moving freely around the
nucleus as suggested by classical physics. He introduced the
idea that electrons can only occupy certain discrete energy
Planetary Model levels, and they can jump between these levels by absorbing or
emitting specific amounts of energy. Bohr's model, known as
the Bohr model, successfully explained the spectral lines of
hydrogen and provided a framework for understanding atomic
structure and behavior, particularly in the context of quantum
mechanics.
Erwin Schrodinger (1926)
Erwin Schrödinger's atomic theory, formulated in the 1920s,
introduced a mathematical description of the behavior of
electrons within atoms, known as quantum mechanics.
Schrödinger developed an equation, called the Schrödinger
equation, which describes how the probability of finding an
Quantum Model electron at a particular location within an atom change over
time. Unlike Bohr's model, which defined electron orbits as
specific paths, Schrödinger's model described electron behavior
in terms of probability distributions or electron clouds. This
wave function approach provided a more accurate and
comprehensive understanding of atomic structure, leading to
the modern quantum mechanical model of the atom.
