1. Instructional Objective: 1. Learn the atomic models 2
Instructional Objective: 1.Learn the atomic models 2.Learn the atomic structure and elements.

2. History of the Atomic Model
The Greek Model
Dalton’s Model
Thomson’s Model
Rutherfords Model
Bohr’s Model
The Wave-Particle Model

3. The Greek Model
Proposed around 400 B.C. By the Greek Philosopher Democrats
Called them “Atomos”, in Greek means can’t be divided or destroyed.

4. John Dalton’s Model
Proposed the Atomic Theory in 1803
All atoms are made up of solid indivisible particles.
* Elements differ in their atom’s size

5. J. J. Thomson’s Model Proposed in 1897 “raisin bread”model
Believed that protons and electrons were mixed together
Known as the “plum pudding” or
“raisin bread”model

6. Ernest Rutherford’s Model
Proposed in 1907 after discovering atom’s nucleus
Electrons move around a central nucleus
containing protons. .

7. Niels Bohr’s Model
Electrons move in energy levels around a central nucleus
Electrons can only be in these energy levels.

8. Particle-Wave Model James Chadwick discovers neutron in 1935.
Electrons are most likely
found in energy levels

9. What is an Atom? *The smallest unit of a matter is known as an atom
What is an element?
An element is made up of only one kind of atom.
What is a molecules ?
Is the smallest unit of a compound
What is a substance?
any element or compound

10. Structure of an atom
An atom is made up of a nucleus that contain protons and neutrons.
And an outer orbit that contain electrons.
-Protons are always positive in charge
-Electrons are negative in charge
-Neutrons are neutral or without any charge

11. Characteristics of an Atom
Atom itself has no charge because protons are always equal to electrons.
Ex: Sodium –Protons are 11
--Electrons are also 11
( Positive and negative will cancel each other)

12. Properties of subatomic particles
Protons, electrons and neutrons are the subatomic particles
Protons are always positive in charge
Electrons are negative in charge
Neutrons are neutral or with out any charge

13. Difference between atomic mass and Atomic number
Atomic mass: is the total number of protons and neutrons in the nucleus.
Atomic number: Is the total number of protons

14. Element Block from periodic table
atomic number Cl Symbol
Chlorine –Name
atomic mass or
mass number 17 Cl
Chlorine
35.45

15. Other Symbols to remember
p+ →Proton(always positive charge)
e- → electron (always negative in charge)
N0 → Neutrons(zero charge)
<→Less than
> →greater than
+ → and or plus
→ → yield
(s) → solid
(l) → Liquid
(g) → gas

16. ISOTOPES.
Atoms of the same element that have different number of Neutrons.
Ex: The most common isotope of hydrogen.
-Hydrogen has no neutrons at all(1proton)
-Deuterium, with one neutron (1proton+1neutron)
- Tritium, with two neutrons.(1proton+2 neutrons)
          
       
                  
                

17. Isotopes can be written as the part of a chemical symbol
Ex: N or Nitrogen – 15 ( 15 is the mass number and 7 is the atomic number)
Ex: 3517Cl or Chlorine -35( 35 is the mass number and 17 is the atomic number)
Close to the atomic mass, abundant is the element in that Isotope.

18. How are electrons arranged in an atom
Electron Cloud
The area in an atom where electrons are found
Energy levels
Is the place in the electron cloud
Are in different distance from nucleus
The closest to nucleus –less and weak
Far away from nucleus –more and more powerful

19. The energy levels 1st- contain maximum 2 2nd- contain maximum 8
3rd- contain maximum 18
4th - contain maximum 32

20. Electron Configurations
* Is the arrangement of electrons in the orbitals of an atom.

21. Electron configuration
S orbit- 2 electrons
P orbit-6 electrons
D orbit-10 electrons
F orbit – 14 electrons