Atom Kotkapoorab Fdk

DR.HARI SINGH SEWAK GOVT. SR.SEC.SCHOOL(BOYS) KOTKAPURA (FARIDKOT)

PROJECT ON STRUCTURE OF AN ATOM  PREPARED BY SONU SINGH (IX) RANJIT SINGH (IX) MANJINDER SINGH (IX)

What is ATOM ? All matter whether liquids ,solids , gas are made up of tiny particles called atoms The word atom is derived from the Greek word atom which means indivisible. The Greeks concluded that matter could be broken down into particles too small to be seen. These particles are called atoms.

Structure of an Atom Atoms are composed of three type of particles: • Protons • Neutrons • Electrons.

Structure Discussed  Atoms are composed of three type of particles: protons, neutrons, and electron. Both the protons and neutrons reside in the nucleus. Protons have a postive (+) charge, neutrons have no charge --they are neutral. Electrons reside in orbitals around the nucleus. They have a negative charge (-).

Protons  One of three basic subatomic particles. Protons are located in the atomic nucleus, have a single positive electrical charge, and a mass about equal to a neutron.  Protons carry a positive charge of +1 .The number of protons determines the total quantity of positive charge in the atom.  The number of protons and neutrons

PROTON

Neutrons  One of three basic subatomic particles. Neutrons are constituents of the atomic nucleus, are electrically neutral, and each has mass about equal to the mass of a proton.  Neutrons are the same size as the protons. But their mass is slightly greater than protons.

NEUTRON

Electrons  One of three basic subatomic particles. The electron has a negative electrical charge, orbits the atomic nucleus, and has a mass about 1/2000 the mass of a proton or neutron.  Electrons are tiny,negatively charged particles that form a cloud around the nucleus of an atom. Each electron carries a single fundamental unit negative electric charge or -1.

ELECTRONS

NUCLEUS

Models showing structure of atom

BOHR MODEL  Bohr model shows electrons circling the nucleus at different levels or orbitals much like planets circle the sun. Electrons move from one energy state to another but can only exist aft defineite energy levels. The energy absorbed or released when electrons change states is in the form of electromagnetic radiation.

Properties of an Atom Properties of atom helps us understand difference between different kinds of atoms.

 Atomic Number  Atomic Mass

Atomic Mass  The Atomic mass also called atomic weight represents the number of neutrons and protons in nucleus.  Protons and neutrons are responsible for most of the atomic mass . The mass of an electron is very small (9.108 X 10-28 grams).

Atomic Number  The atomic number of an atom represents the number of protons in its nucleus.  It is the number of protons that determines the atomic number, e.g., H = 1. The number of protons in an element is constant (e.g., H=1, Ur=92) but neutron number may vary, so mass number (protons + neutrons) may vary.