1. Atoms: The Building Blocks of Matter
Unit 2

2. Introduction to the Atom
Modern Atomic Theory
Subatomic Particles
Isotopes
Ions
Essential Standards and objectives:
1.1.1 Analyze the structure of atoms, isotopes, and ions.
1.1.2 Analyze an atom in terms of the location of electrons.
1.1.3Explain the emission of electromagnetic radiation in spectral form in terms
of the Bohr model.
Explain the process of radioactive decay using nuclear equations and half-life.
2.2.5 Analyze quantitatively the composition of a substance. (Introduction to moles)

3. Agenda 2/6: Purpose: To determine the structure of an atom
Warm-up: Reading on Atoms
Atomic Theory
Atomic Structure
How is it represented?
Isotopes
How are isotopes represented?

4. Reading: Cornell notes
Essential questions: What are the characteristics of an atom? In your notes: address both individual atoms and atoms of an element

5. The Atom: Smallest particle of an element that retains the chemical properties of the element.
Essential Questions:
What is an atom?
What is its structure?
What determines properties of an element?

6. Atoms act in orderly, predictable ways.

7. Modern Atomic Theory All matter: Atoms of a given element:
Atoms cannot be created nor destroyed in:
In chemical reactions, atoms are

8. Atomic Theory (cont.) To form compounds: Law of Definite Proportions
Law of Multiple Proportions

9. Summary Table: Atomic Structure- Subatomic Particles
Subatomic Location Charge Mass Importance
Particle AMU

10. AMU = relative measurement and used for comparison
Atomic
Mass Unit
AMU
 The “amu” is defined as one twelfth of the mass of an atom of carbon-12  (with 6 protons and 6 neutrons) and has a value of ×10−27 kg.

11. How small is an atom?

12. Designation of Atomic Structure
Atomic number (Z):
On the Periodic Table:
Mass number (A):

13. Designations for the Atomic Structure Atomic number (Z):
On the Periodic Table
Mass number (A): 20 Ca
40.08

14. Isotopes

15. Isotopes - Discovery Education Video

16. Isotopes (“versions” of the same element)
Atoms of an element with different masses
Naturally occurring
Some are stable and some are radioactive (unstable)
Isotopes of an element have the same number of ___________ and a different number of ______________.

17. Identifying Isotopes Isotope Notation 1. 2.
On the Periodic Table, the number with the
Decimal point is:

18. Review: What is Z. What is A
Review: What is Z? What is A? Determine the number of protons, neutrons, and electrons.
In Nature, 12 C 6 6 C
Carbon
12.011
Occurs 98.89%
frequency 13 C 6
Occurs
1.11 %
frequency

19. Atoms of the Same Element

20. Atoms of the Same Element

21. Atomic Mass Weighted Average Mass of isotopes
Based on the percentage of each isotope present.
Mass Abundance
C x =
C x 1.11=

22. Grades are often computed using a weighted average.
Suppose that homework counts 10%, quizzes 20%, Labs 10% and tests 60%.
If:
homework grade is 92
quiz grade is 68
lab grade is 88
test grade is 81
What’s the overall grade?

23. Practice - Worksheet Atomic Structure Atomic Number & Isotopes
Identify the number of proton, neutron, & electrons of an atom of a specific element
Rounding the atomic mass on the Periodic Table gives the mass of the most common isotope
Atomic Number & Isotopes
Correct symbol: A & Z
Complete the table
Complete the questions.

24. Atomic Number & Isotope

25. Practice: - worksheet Find the Average Atomic Mass
Nucleus of each atom is represented
Graphic below #4 - explains #5-7
Isotopes: Atomic Number & Mass Number
Determine based on the chart – not the PT
2 Isotope notations
Element – A (X-A) A ZX

26. Find Average Atomic Mass

27. Isotopes: Atomic Number & Mass Number
Element
Isotope
Symbol
Atomic
Number Z
Mass A
# of protons
# of neutrons
# of electrons

28. Review & Explain: How does this graphic demonstrate the
characteristics of an atom?
Make sure that you include each graphic representation in your explanation

29. Atom: Scanning Tunneling Microscope

30. Development of the Modern Atomic Model
Here are several models of the atom as they were developed in history:
Development of the Modern Atomic Model

31. History of Discovering the Atom