Atoms, Elements and the Big Bang Theory

• Anything that occupies space is matter
• Matter has mass
• Chemistry deals with the study of matter
• Elements cannot be broken down into simpler substance
• An atom is the smallest particle of an element

Sub atomic particles

• Neutron = Zero charge
• Proton = Positive charge
• Electron = Negative charge

Big Bang Theory

• Universe developed 13.7 billion years ago from a very small, dense, and hot state
• This is called Singularity which started to collapse and expand

Big Bang Nucleosynthesis

• Creates new atomic nucleus from preexisting nucleons
• Light elements formed include Hydrogen, Helium, Lithium, and Beryllium

Nuclear Fusion

• Combines two nucleus's to produce a new element

Stellar Nucleosynthesis

• Lighter elements are fused together within a start to create another element

Supernova Nucleosynthesis

• Responsible for creating rarer elements heavier than iron and nickel

History of the Atom

• Leucippus and Democritus called the small pieces of matter as "Atomos", which means indivisible
• Aristotle affirmed that there are four elements: Fire, Water, Earth and Wind
• John Dalton proposed the modern atomic theory

Modern Atomic Theory

• All matter is composed of atoms
• Atoms cannot be subdivided, created, or destroyed in ordinary chemical reactions
• Atoms of an element have a characteristic average mass which is unique to that element
• Atoms of any one element differs in properties from atoms of another element

J.J. Thompson

• Formulated the plum pudding model of the atom
• The electron particles are like plums in a positively charged pudding
• He used the cathode ray tube experiment to formulate this model

Ernest Rutherford

• Formulated the nuclear model of the atom
• Electrons revolve around a positively charged center of the atom which he called the nucleus
• He used the gold foil experiment where he bombarded it with alpha particle

James Chadwick

• Conducted the same experiment as Ernest Rutherford; Instead of using gold, he used barium
• With his experiment, he was able to discover the subatomic particle neutron

Neils Bohr

• Modified and improved the nuclear model of the atom of Ernest Rutherford
• Placed the electrons in specific energy level to create a planetary atomic model

Atomic Number and Atomic Masses

• Number of Protons = Atomic Number
• Number of Electrons = Number of Protons
• Number of Neutrons = Atomic mass minus number of Protons
• Atomic Mass = No. of Protons plus No. of Neutrons
• Isotopes elements with the same atomic number but different atomic mass
• Formula for isotopes = Ā = (%)(A₁) + (%)(A₂)

Periodic Table of Elements:

• Johann Wolfgang Dobereiner's law of Triads: First to arrange the elements into three
• John a Newlands' Law of Octaves: Arranged the elements according to increasing atomic weight where the chemical properties repeat in an interval of eight
• Dmitri Mendeleev's Periodic Table: arranged the elements according to increasing atomic weight and was first to tabulate the elements
• Henry Moseley's Periodic Table: Arranged the elements according to increasing atomic number

This lesson explores the fundamental concepts of matter, elements, and atoms, including subatomic particles and their charges. It further describes the Big Bang theory, nucleosynthesis, nuclear fusion, and how these processes create elements. It also touches on the history of the atom.