1. Chapter 5

2. What are the Subatomic Particles?
Proton
Neutron
Electron

3. The Atom and Subatomic Particles
Cloud model Bohr Model
(a)
(b)
Cloud of negative
charge (2 electrons)
Electrons
Nucleus
Neutrons
Protons

4. Subatomic Particles are. . .
Neutrons
Found in the nucleus of the atom
Have no charge (neutral)
Have a mass of amu
Protons
Found in the nucleus
Have a positive charge
have a mass of amu
Electrons
Found orbiting the outside of the nucleus
Have a negative charge, a mass of
If the atom has no charge there are the same number of electrons to protons

5. Subatomic Particle Particle Mass (amu) Charge Location Proton 1.0073 +
Nucleus
Neutron
1.0087
Neutral
Electron
0.0006 -
Electron Cloud

6. Reading the Key on a Periodic Table:
The Mass Number: Shows the Atomic Mass as a decimal, round that to a whole number to write the Mass Number. Includes # of protons plus # of neutrons.
Symbol: Can be one Uppercase letter and one lower case letter or one uppercase Letter only!
Atomic Number: This provides the total number of Protons in the element’s atom.

7. Atomic Structure Atomic Mass: 39 Symbol: K Element: Potassium
Mass Number :
Includes the averaged mass of the number of protons and neutrons added together.
This number is equal to the number of protons plus the number of neutrons.
Atomic Mass: 39
Symbol: K
Element: Potassium
Atomic Number: 19

8. Atomic Number: 15 7N Nitrogen Mass Number Atomic Number
Tells you the total number of protons in the nucleus.
When an atom has no charge/neutral, the number of protons are equal to the number of electrons!
Elements on the Periodic Table are placed in order of the Atomic Number
15 7N Nitrogen
Mass Number
Atomic Number

9. How to Solve for the number of Neutrons?
Subtract the Atomic Number from the Mass Number. OR
Subtract the Number of protons from the Mass Number
Subtract the Number of Electrons from the Mass Number.

10. Aristotle Democritus Greek philosopher
Believed that there were only four elements of matter:
water
fire
Earth
air
Greek philosopher
Believed that matter cannot be divided into small pieces forever.
He named the smallest piece an atomos,
Atomos is Greek for atom.
Atomos means indivisible.
Atom: the building block of all matter.

11. Dalton: The Proposed Atomic Theory
All elements are composed of atoms. Atoms are indivisible and indestructible.
Atoms of the same element are exactly alike.
Atoms of different elements are not alike.
Compounds are formed by the joining of atoms of two or more elements.

12. Thomson’s Model
1897: Thomson proposed that the atom is made of small particles.
He explained that there were positive and negative charges scattered throughout.
”plum pudding”

13. Rutherford’s Model
Proposed that the atom is mostly empty space filled with positive charges.
Proposed that the positive charged particles were in the center of the atom, called the nucleus.
Outside the nucleus were negative electrons scattered throughout the edge of the atom.

14. Niels Bohr
1913: Bohr believed that the electrons traveled in a definite orbit with certain energy levels and certain distances from the nucleus.
Each energy level can hold a certain amount of electrons.

15. The Bohr Model
According to the Bohr model each energy level can hold a certain number of electrons.
Starting from the first energy level outside of the nucleus:
Level 1: 2 electrons
Level 2: 8 electrons
Level 3: 18 electrons
Level 4: 32 electrons
Level 5: 32 electrons

16. Modern Atomic Model
Today we believe that the electrons do not travel a certain path.
They do have a certain energy level.
They are always moving
Electrons can gain or lose energy and bounce up energy levels or down energy levels.

17. Drawing The Bohr Model and writing the electron configuration sequence
According to the Bohr model, each energy level can hold a certain number of electrons.
Energy Levels, starting from the first energy level outside of the nucleus :
Level 1: 2 electrons
Level 2: 8 electrons
Level 3: 18 electrons
Level 4: 32 electrons
Level 5: 32 electrons
How do you write out an electron configuration?
Write out and draw the Electron Configuration Sequence and the Bohr Model for each of the following:
Example 1: Sr Example 2: U

18. Element’s Key and the Bohr Model:
Second
shell
Helium
2He
First
Third
Hydrogen 1H 2 He
4.00
Atomic mass
Atomic number
Element symbol
Electron-shell
diagram
Lithium
3Li
Beryllium
4Be
Boron 3B
Carbon 6C
Nitrogen 7N
Oxygen 8O
Fluorine 9F
Neon
10Ne
Sodium
11Na
Magnesium
12Mg
Aluminum
13Al
Silicon
14Si
Phosphorus
15P
Sulfur
16S
Chlorine
17Cl
Argon
18Ar
Figure 2.8

19. What is an Isotope? Isotope:
An atom of the same element that has the same number of protons but different number of neutrons.
The Mass Number will change if an isotope exists.
Proton number remains the same!
Remains the same element.

20. What is a Quark?
Theory states that there is a different particle that makes up the particles found in the nucleus, known as a Quark.
The proton and neutron are composed of three different quarks that make up their charge or no charge.
Quarks that make up a Proton: +2/3 +2/3 -1/3 = +1 Quarks that make up a Neutron: +2/3 -1/3 -1/3 = 0

21. You complete me!! The Octet Rule
Atoms want to achieve a complete outer shell of 8 electrons, with exception to helium. Helium only has 2 electrons and has a complete outer shell of two.
How do atoms achieve this happiness??
By forming bonds.
We can represent the completion of the outer shell by drawing a picture known as the Lewis Dot Diagram.

22. Closure Exit Ticket
Explain how you observed atomic forces in one complete sentence.
Draw the Bohr Model of the element Phosphorous.
Find the following for phosphorous:
Number of protons
Number of neutrons
Number of electrons
Mass number
Atomic number.

23. The Four Forces
Electromagnetic
Strong
Weak
gravity

24. Electromagnetic Force
Electromagnetic force: an attraction or repulsion between particles.
If the particles have the same charge they are repelled.
Opposite charges attract
Electrons are kept in orbit because of opposing attraction for the proton
But what keeps the positive protons from repelling each other???

25. Strong Force Opposes the electromagnetic force’s repulsion of protons!
It is the glue for the nucleus!
Without the strong force the atom would not stay together.
Only works when the protons are close.
It is the strongest of the forces.

26. Weak Force: Gravity: Is the power for the sun the weakest force
Is responsible for radioactive decay
Radioactive decay: is when the neutron changes into a proton and electron
Gravity:
the weakest force
Is the force of attraction exerted between all objects in nature.
Not clearly understood

27. Closure Which force is the weakest and why?
Which two forces keep the atom’s structure?