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  • 1. IntroductionMade By :- Sanyam Ohra Class :- IX th A Submit To :- Veer Sir Roll No :- 20
  • 2. Particles• Atoms• molecules
  • 3. Whats an atom? Definition:A microscopic small particle that could notbe made any smaller and still behave as a chemical system. Atoms are the smallest particles that can exist and represent elements identity. Atoms cannot be created or destroyed
  • 4. Atoms• Atoms consist of protons, neutrons, electrons• The atomic structure is shown in the diagram below• Protons have positive charge• Electrons have negative charge• Neutrons have no charge
  • 7. Properties Particle Mass (kg) Mass (amu)# Charge*Electron 9.10939 x 10 -31 0.00055 = 0 -1Proton 1.67262 x 10 -27 1.00728 = 1 +1Neutron 1.67493 x 10 -27 1.00866 = 1 0
  • 8. Atoms• Sub-atomic particles• Electrons• Protons• Neutrons
  • 9. ATOMIC PARTICLES:• Atoms consist of three subatomic particles:• electrons – electrons are negatively charged particles and their properties are summarized in the following table• protons – protons are positively charged particles and their properties are summarized in the following table• neutrons – neutrons have no charge and their properties are summarized in the following table
  • 10. ELECTRONS• Small negatively charged particle• Orbit, circle, around the nucleus• Have no mass.• Atoms are neutral.• Number of electrons = number of protons
  • 11. PROTONS:• small, positively charged particles• reside in the nucleus• along with the neutron, make up most of the mass of the atom• the number of protons is what defines the type of a particular atom.• Atoms are neutral• Number of protons = number of electrons
  • 12. NEUTRONS:• small particles with no charge• reside in the nucleus• along with the proton, make up most of the mass of the atom
  • 13. ATOMS--Daltons Atomic Theory• All matter (including elements) is composed of atoms; each atom is a very small, chemically indivisible particle – the word atom is from the Greek word "atmos" which means "cannot be cut apart"• elements are different because they are composed of different types of atoms• each type of atom has properties different from other atoms
  • 14. Atomic theory of matter• Matter composed of atoms• Atoms of given element have identical properties• Different elements have different properties• Atoms combine in whole number ratios• Not created or destroyed in ordinary chemical reactions
  • 15. Whats a molecule? Definition:The smallest particles of an element or compound that can exist and retain the chemical properties of that element or compound
  • 16. Molecules•Molecular formula gives composition:number of atoms of each elementpresent•Molecular mass= sum of masses ofatoms
  • 18. Examples of molecules
  • 19. Representing molecules• Names: ethanol, ethyl alcohol•Formulas: C2H8O, C2H5OH, CH3CH2OH•Structural drawings•Models