All matter is made up of small particles called atoms.

Atoms are indivisible (Burp!)

Atoms cannot be created, destroyed, or changed.

All atoms of a given element are alike (Ahem!)

In a chemical reaction, atoms are divided.

Cathode rays consist of negatively charged particles called electros, which are present in all atoms.

Cathode Rays travel in straight lines

Cathode rays consist of a stream of fast moving particles

Cathodes attract positively charged particles.

Cathode rays are made up of negatively charged particles (i.e., electrons)

Electrons are the lightest subatomic particle with just 9.1 * 10 ^-28 grams of mass.

They have a definite charge and a definite mass, irrespective of the element that they are a part of.

They determine the Atomic number of an element.

They determine the Atomic Mass of an element.

An electron carries 1.602 *10 ^-19 Coloumb of negative charge. This is one unit negative charge.

This image indicates the experiment of Eugene Goldstein that led to the discovery of protons.

This is the Cathode Ray experiment of JJ Thompson.

The Cathode rays are deflecting towards the positively charged region. This proves that they are negatively charged.

This experiment was conducted in 1902.

Dalton's Atomic Model

Thompson's Atomic Model

Bohr's Atomic Model

Rutherford's Atomic model

1808 Dalton's Atomic Theory

1897 Rutherford's Gold foil experiment

1878 Thomson's Cathode Ray experiments

1886 Eugen Goldstein Discovery of protons

1878 Sir William Crookes Cathode Rays

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Protons have a mass of 1.6* 10^-24 grams, making it about 1/1837th of the mass of an electron.

Protons have an equal and opposite charges as that of an electron.i.e., 1.602 *10^-19 Coulomb of positive charge.

An atom always has an equal number of neutrons, protons, and electrons to be chemically stable.

Protons were discovered because anode rays moved through a perforated cathode.

Why did 1 Helium atom weight 4 times that of a Hydrogen atom, if it had only twice the number of protons?

Why did majority of the positively charged alpha particles move straight through a thin gold foil?

Why did the cathode rays bend towards the positively charged anode?

Atomic number indicates the number of electrons in an atom.

Atomic mass indicates the mass contained in the atom. It is written as a superscript to the symbol of the element.

Schrodinger's quantum model of the atom is the currently accepted version of the atom.

Valency, Protons, Inert, Valence Shell, solids.

Valence Shell, Valency, Neutrons, Inert, tetravalent.

Valence Shell, Electrons, Valency, Inert, gases

Ions are when the same element has atoms with different mass.

Ions are positively or negatively charged particles.

Positively charged ions are called cations and negatively charged ions are called anions

Some elements demonstrate more than one valency. It is called Variable valency. Iron is one such element.

Carbon has 3 isotopes - C12, C13, C14

Isotopes are formed when some atoms of an element have a different mass from the others.

The difference of mass is caused by the number of neutrons in the nucleus.

All isotopes of an element have the same physical and chemical properties and the same valency.

The Octet and Duplet rule are related to the chemical stability of an atom.

The Atomic mass of an isotope differs from another isotope of the same element.

The Atomic Mass of a radical differs from the Atomic Mass of an ion.

Positively charged radicals are called base radicals and negatively charged radicals are called acid radicals.

A radical is an atom or a group or atoms of different elements that behave as a single unit. An ion is related to a single atom of one element.