chapter 4 atomic structure. define democritus’s ideas about atoms explain dalton’s atomic...

CHAPTER 4ATOMIC STRUCTURE

Define Democritus’s ideas about atoms

Explain Dalton’s Atomic Theory

Identify what instrument is used to observe individual atoms.

4.1 OBJECTIVES

Prior Knowledge- We learned in chapter 2 that an element is the simplest form of matter that has a unique set of properties.

The question we must ask and answer is what is an element composed of, and how do we observe the individual atoms.

EARLY MODELS OF THE ATOM

To begin we have to first look into what all matter is composed of.

An atom is the smallest particle of an element that retains its identity in a chemical reaction.

KEYWORD: ATOM

EARLY MODELS OF THE ATOM

Democritus believed that atoms were indivisible and indestructible.

EARLY MODELS OF THE ATOM

By using experimental methods, Dalton transformed Democritus’s ideas on atoms into a scientific theory.

This led to what is know as Dalton’s Atomic Theory: All elements are composed of tiny indivisible particles

called atoms. Atoms of the same element are identical. Atoms of different elements can physically mix

together or can chemically combine to form compounds.

Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.

KEYWORD: DALTON’S ATOMIC THEORY

DALTON’S ATOMIC THEORY

The Rutherford Atomic model pioneered the atom into what it looks like today.

In his model, the nuclear atom, the protons and neutrons are located in the nucleus. The electrons are distributed around the nucleus and occupy almost all the volume of the atom.

KEYWORD: Rutherford Atomic Model

THE DEVELOPMENT OF ATOMIC MODELS

THE GOLD FOIL EXPERIMENT

Niels Bohr proposed in 1913 that an electron is found only in specifi c circular paths, or orbits, around the nucleus. (THE NEILS BOHR MODEL)

KEYWORD- BOHR MODEL

THE BOHR MODEL

In 1926 a scientist by the name of Erwin Schrodinger developed a theory which is commonly used today.

This concept is the Electron Cloud Model, which states the allowed energies an electron can have and the various locations it can appear.

KEYWORD: ELECTRON CLOUD MODEL

SCHRÖDINGER AND THE ELECTRON CLOUD