1. Atomic Theory and Structure Overview
Organizing Matter
Relative Masses
Atomic History and Theory
The Modern Periodic Table
Structure of an Atom
Ions
Atomic Mass
Isotopes

2. Organizing Matter
As scientists were discovering different elements, it became apparent that they needed a way to organize them
At first they were organized by their atomic mass
Dimitri Mendeleev – the “founder” of the periodic table, did this.

3. TeachWithFergy Preview File
Please enjoy this preview of your Student Version of the Power Point.
Some slides appear blank because they have been removed.
Student versions have portions of the text removed which is given in the teacher version and appear as ______
Other slides may have on them, this represents writing that has been removed.
Please note that the Entire Unit Package can also be purchased at a steep discount from my Store.

4. Relative Masses Carbon was found to be 12X as heavy as Hydrogen
____________
Hydrogen has such a small mass it becomes difficult to compare masses relative to it
Instead, we compare the relative atomic mass of all elements to that of Carbon-12
Therefore, we define the unified atomic mass unit (u) as of the mass of a carbon-12 atom
_____________
So… H has a mass of 1 u, C is 12 u and O is 16 u

5. Mendeleev’s Periodic Law
Arranging elements in order of increasing atomic mass worked relatively well, but some discrepancies resulted:
For example: K and Ar.
The mass of Potassium is less than that of Ar.
Today, elements on the periodic table are arranged by increasing Atomic Number (number of protons)

6. Dalton’s Atomic Theory – The Ball Model: 1800s
Referred to the atom as a small, hard, indestructible sphere that cannot be subdivided
An atom is ……………
An element is a substance made up of only 1 type of atom
____________

7. This slide has been removed

8. This slide has been removed

9. Ernest Rutherford’s Gold Foil Experiment - 1911
“+” charged particles (alpha particles) were fired at a thin sheet of gold foil
____________

10. What he thought would happen given the “Plum Pudding” Model...
Some alpha particles would be slightly diverted due to their ………………..
The above diagram shows what we would expect the result of Rutherford’s experiment to be if the “plum pudding” model of the atom is correct.

11. This slide has been removed

12. Rutherford’s Findings
Most of the particles passed right through
A few particles were deflected
_____________
Egads! It’s like shooting bullets at tissue paper and watching them bounce back

13. The Rutherford Atomic Model
Based on his experimental evidence he concluded that the atom:
Is mostly empty space
Contains a small, dense, positively charged nucleus at the centre
____________

14. This slide has been removed

15. The Bohr-Rutherford Model
____________
Electrons move in orbits (energy levels) around the nucleus
Electrons more or less stay in their orbit unless an increase in energy causes them to move

16. Modern Periodic Law
Elements arranged in order of increasing atomic number and show a periodic repetition of properties

17. This slide has been removed

18. Check Your Understanding
Determine the number of protons, neutrons, and electrons for the following elements *Round each atomic mass to the nearest whole number*
_____________ 13 Al
26.98
protons = ____________ 79 Au
196.97
______________
= ______________
________________ 99 Es
253.08
= _____________
_______________ 40 Zr
91.22
91 – 40 = ____________

19. This slide has been removed

20. Atomic Mass
The number of protons in the nucleus determines the identity of the element and is referred to as the ___________
___________

21. Calculating Atomic Mass
An element’s atomic mass (A), having an atomic number (Z) and a specific number of neutrons (N)
____________
Most of the atomic masses on the periodic table are not integers (1, 2, 3, etc.). __________
Isotopes are elements that have the same number of protons ____________
Therefore, they have a different atomic mass

22. Isotopes
Periodic table states Average Atomic Masses, which take into account _______________of isotopes of each element, as well as ___________
Symbol
Isotope
Protons
Neutrons
Electrons
Abundance
35Cl
Chlorine-35 17 18
75.77%
37Cl
Chlorine-37 20
24.23%

23. This slide has been removed

24. Calculating Average Atomic Mass
When calculating average atomic mass, the fraction of each isotope must be determined
Typically, we are given abundance in a percentage. So we need to convert to a decimal before using it to calculate atomic mass
*AM represents atomic mass*

25. Check Your Understanding
Calculate ………………….
Isotope
Relative Atomic Mass
Abundance (%)
C-12 12
98.89
C-13
13.003
1.11
Given Information:
Equation:
Solve
Therefore……………..

26. This slide has been removed

27. Radioisotopes Isotopes that are radioactive
Radioactive isotopes release radiation as they decay and change into other isotope of a given element
These isotopes are unstable emit and radiation as their nucleus changes
_____________

28. This slide has been removed

29. What are Isotopes used for?
______________
Deuterium is the isotope of hydrogen with a nucleus of one proton and one neutron. It occurs naturally in water to a small concentration
The main use at present is as heavy water, which is deuterium oxide (equivalent to H2O), _________________