The Atom

• Dalton’s Atomic Theory: All matter is made up of indivisible atoms which cannot be created or destroyed.
• William Crookes discovered the Electron. Cathode ray tube.
• JJ Thomson determined that electrons were negative. Found E/M ratio.
• Robert Millikan’s Oil drop experiment discovered size of electron’s charge.
• Plum Pudding Model: Solid positive sphere with electrons embedded.
• Rutherford discovered the Nucleus. Fired alpha particles at gold foil. Proton.
• Chadwick discovered the neutron by firing alpha particles at beryllium.
• Energy level is the fixed energy value that an electron in an atom may have.
• Heisenberg’s Uncertainty Principle states that it is... (More)

General Definitions

• Organic Chemistry is the study of compounds of Carbon.
• Hydrocarbons are carbons consisting of carbon and hydrogen only, bonded together covalently. They are used as fuel and feedstock for the chemical industry. Main Sources: Coal, Methane, Crude Oil.
• Structural isomers are compounds that have the same molecular formula but different structural formulas.

Homologous Series is defined as:

1. A series of compounds of uniform chemical type.
2. Showing gradations in physical properties.
3. Having a general formula for its members.
4. Each member having similar chemical properties & preparation.
5. Each member differing from the previous by a CH2 unit.... (More)

Matter is composed of very small particles which may be atoms, molecules or ions.

The History of the Atom

The Greek philosophers first proposed that there were indivisible particles which they called ‘atoms’ which means ‘indivisible’ in Greek. This is where we get the word atom.

John Dalton

In 1808, an English chemist called John Dalton was able to provide indirect evidence for the existence of atoms.

Dalton’s Atomic Theory:

1. All matter is made up of very small particles called atoms.
2. All atoms are indivisible. They cannot be broken down into simpler particles.
3. Atoms cannot be created or destroyed.... (More)

To understand the arrangement of electrons in atoms, Neils Bohor understood the spectra. When white light (eg. sunlight or light from an ordinary electric light bulb) is passed through a prism, the white light is broken up into many different colours. This called a continuous spectrum. But when Bohor carried out this experiment with a hydrogen discharge tube (a glass tube filed with hydrogen at low pressure through which an electric current is passed) instead of white light, he found that instead of seeing a continuous spectrum, he saw a series of narrow lines. These lines are called line... (More)