Str Of Atom Golewala Fdk

Project Name

Structure of Atom G.CO-EDU.SEN.SEC.SCHOOL GOLEWALA(FDK)

Prepared By:Students Name Class 1.Manpreet Kaur 9th (Collect Topic) 2.Sandeep Kaur 9th (Editing) 3.Hardeesh Kaur 9th (Write) 4.Sukhveer Kaur 9th (Color) 5.Gurpreet Kaur 9th (Pictures) Spl Thanks :- Monika Gupta (Sci.Mistress)

INDEX 1. 2. 3. 4. 5. 6. 7. 8. 9.

Atom as building block. Discovery of electron. Cathode ray tube. Properties of cathode rays. Discovery of proton. Discovery of neutron. X-Rays & its properties. Models of atom. Isotopes.

ATOM AS BUILDING BLOCK OF MATTER • Atom, tiny basic building block of matter. All the material on Earth is composed of various combinations of atoms. Atoms are the smallest particles of a chemical element that still exhibit all the chemical properties unique to that element. • When two or more atoms combine, they form a molecule. For example, two atoms of the element hydrogen (abbreviated H) combine with one atom of the element oxygen (O) to form a molecule of water (H20). • The smallest particle of an element or of a compound that has independent existence is a molecule.

•Acc. to Dalton’s Atomic theory matter is made up of tiny particles known as atom. .Atoms were not divisible. But latter on it is discovered that atom is divisible. It is made up of electron, protons & neutrons. These are called Fundamental particles. •There systematic study is as:-

DISCOVERY OF ELECTRON Cathode Ray, a high-speed electron emitted by the negative electrode of a vacuum tube when an electric current is passed through it. Cathode rays were first generated by means of the Crooke's tube, an invention of the British physicist Sir William Crooke.

Cathode Ray Tube

PROPERTIES OF CATHODE RAYS 1. 2. 3. 4. 5. 6. 7. 8. 9.

They travel in straight line. They are made up of material particles. They have negative charge. They produce heating effect. They produce X-Rays when they strike the surface of hard metals. They posses penetrating effect. They effect photographic plates. They cause ionization of a gas through which they pass. They produce green fluorescence. The negatively charged material particles constituting the cathode rays are called Electrons.

ELECTRON:nearly

An electron is that fundamental particle which carries 1unit negative charge & has a mass

DISCOVERY OF PROTON-STUDY OF ANODE RAYS since the atom as a whole is electrically neutral and the presence of negatively charged particles in it is established. Therefore it was thought that some positively charged particles must also be present in the atom. For this purpose Goldstein performed discharge tube experiments in which he discovered anode rays. •

PROPERTIES OF ANODE RAYS:-

4. They travel in straight line. 5. They are made up of material particles. 6. They are +ively charged. These particles are called protons. PROTON:- A proton may be defined as that fundamental particle which carries 1 unit +ive charge and has a ,mass nearly equal to that of hydrogen atom.

DISCOVERY & STUDY OF NEUTRONS James Chadwick, in 1932 performed some scattering experiments in which he bombarded some light elements like Beryllium & Boron with fast moving alpha particles. He found that some new particles were emitted which carried no charge. This was termed as NEUTRON. NEUTRON:- A neutron may be defined as that fundamental particle which carries no charge but has a mass nearly equal to that of hydrogen atom or proton.

X-RAYS:-

X Ray, penetrating electromagnetic radiation, having a shorter wavelength than light, and produced by bombarding a target, usually made of tungsten, with highspeed electrons.

Properties of X-Rays:4. X rays affect a photographic emulsion in the same way light does . 5. X rays also cause fluorescence in certain materials. 6. X-Rays have high ionization power. 7. X-Rays travel in straight line. 8. X-Rays have no charge. 9. X-Rays may be diffracted by passage through a crystal or by reflection

Models of the Atom

ISOTOPES OF HYDROGEN Atom of an element that have same atomic no. but different mass no. are called ISOTOPES