STRUCTURE OF AN ATOMBY IRA DEOKULE VIII J ROLL NO. 6

Developments in the model of atom

Dalton’s ModelAlso known as the billiard ball model

• All matter is made up of tinyparticles called atoms.

• All atoms of a given element area like, but are different from theatoms of any other element.

• Compounds are formed whenatoms of different elementscombine in fixed proportions.

• A chemical reaction involves arearrangement of atoms, not achange in the atoms themselves.

Thomson’s ModelAlso known as the plum pudding or water melon model

Rutherford’s Model

• The atom's electron cloud does not influencealpha particle scattering.

• Much of an atom's charge (specifically, itspositive charge) is concentrated in a relativelytiny volume at the nucleus.

• The magnitude of this charge is proportional to(up to a charge number that can beapproximately half of) the atom's atomic mass -the remaining mass is now known to be mostlyattributed to neutrons.

• This concentrated central mass and charge isresponsible for deflecting both alpha and betaparticles.

• The mass of heavy atoms such as gold is mostlyconcentrated in the central charge region.

Parts of the atom

Nucleus• A model of the atomic nucleus

showing it as a compact bundle of

the two types of nucleons: protons

and neutrons.

• In simple diagrams they look like little

balls stuck together but an actual

nucleus cannot be explained like this

but only by using quantum

mechanics.

• In a nucleus which occupies a

certain energy level each nucleon

can be said to occupy a range of

locations.

Neutron• The neutron is a subatomic particle

with no electric charge.

• The nucleus consists of a number

of protons and neutrons.

• The mass of the neutron is slightly

larger than that of proton.

• In the nucleus, the protons and

neutrons are bound together

through nuclear force and

neutrons are needed for the

stability of the nuclei.

• Even though it is not a chemical

element it is included in the table

of nuclides.

Protons

• The proton is subatomic particle

with a positive electric charge.

• The nucleus consists of a number

of protons and neutrons.

• The mass of the proton is slightly

larger than that of neutron.

• The number of protons in the

nucleus is referred to as it’s

atomic number.

Electrons• The electron is a subatomic

particle with a negative charge.

• The mass of the electron is

approximately 1/1836 that of

proton.

• An electron generates a magnetic

field.

• Electrons have many applications,

including electronics, welding,

cathode ray tubes, electron

microscopes, radiation therapy,

lasers, gaseous ionization detectors

and particle accelerators etc.

Thank You