Atoms are the smallest particles that elements are made of and cannot be further broken down while still retaining their chemical properties. Atoms consist of protons, neutrons, and electrons. Protons have a positive charge, electrons have a negative charge, and neutrons have no charge. Molecules are the smallest particles of an element or compound that can exist and retain the chemical properties of that element or compound. They are made of two or more atoms and their molecular formula gives the composition in terms of the number and type of atoms present.

1. Introduction
Made By :- Sanyam Ohra
Class :- IX th A
Submit To :- Veer Sir
Roll No :- 20

2. Particles
• Atoms
• molecules

3. What's an atom?
Definition:
A microscopic small particle that could not
be 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

5. ATOMIC STRUCTURE

6. ATOMIC STRUCTURE

7. Properties
Particle Mass (kg) Mass (amu)# Charge*
Electron 9.10939 x 10 -31 0.00055 = 0 -1
Proton 1.67262 x 10 -27 1.00728 = 1 +1
Neutron 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--Dalton's 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. What's 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 element
present
•Molecular mass= sum of masses of
atoms

17. EXAMPLES OF MOLECULES

18. Examples of molecules

19. Representing molecules
• Names: ethanol, ethyl alcohol
•Formulas: C2H8O, C2H5OH, CH3CH2OH
•Structural drawings
•Models