Atoms & Molecules

2. Atom and Molecules
Prepared By:
Fahad And Arsalan

4. •An atom is the smallest
unit that maintains the
characteristics of an
element
–Nucleus- The center of the
atom, contains protons
and neutrons
–Electron Cloud –Region
surrounding the nucleus
containing the electrons
ATOM

5. The Nucleus
Proton- A positively charged sub-atomic particle (+).The number of protons is
the same as the atomic number
Li
3
7
The atomic massThe atomic mass
The Atomic Symbol
Neutrons– A sub-atomic particle in the nucleus. Neutron do not
have a charge (0)

6. The Electron Cloud
•Electrons-
•The number of electrons equals the number of protons
•Sub-atomic particle with a negative charge (-)
•Mass of an electron is negligible
•Electrons behave as if in a 3-D orbit
•Valence Electrons
– The outer most electrons
–Valence electrons are responsible for bonding

7. Bohr Model
•The first shell can have
2 electrons
•The second can
have 8 electrons

8. Shells and the Electron Cloud

9. Let’s look at a few elements…
Hydrogen 1= Proton1= electron

10. Let’s look at a few elements…
Lithium 3=protons 4=neutrons
3=electrons

11. Let’s look at a few elements…
Argon
18=protons22=neutrons
18=electrons

12. Isotopes
Atoms of the same element with different number
of neutrons
Isotopes of Hydrogen

13. Molecules

14. Molecules
A molecule is defined as a stable neutral
group of at least two atoms in a definite
arrangement held together by very strong
chemical bonds .
It can also be defined as a unit of two or more
atoms held together by covalent bonds.

15. Types Of bonding
Ionic Bond:
Ionic bonds are formed when atoms become
ions by gaining or losing electrons.

17. Covalent Bond:
Covalent bonds form when atoms share electrons.
Since electrons move very fast they can be shared,
effectively filling or emptying the outer shells of the
atoms involved in the bond. Such bonds are referred
to as electron-sharing bonds.

18. Guess What its Video Time

19. The End
Now Please Wake Up for Clapping.