1. Unit:
The Atom
and
The Periodic Table

2. Evolution of the Structure of an Atom

3. Dalton’s Atomic Theory
All elements are composed of indivisible
particles called atoms
Atoms of the same element are identical. The atoms of any one element are different from those of any other element.
Atoms of different elements can physically mix together or chemically combine with one another in simple whole number ratios to form compounds.(law of definite composition)
Chemical rxns occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.(law of conservation of mass)

4. J.J. Thomson
discovered the electron
plum pudding model

5. Rutherford discovered the nucleus
Proposed electrons surround the nucleus in a cloud

6. The Atom Today
The atom is the smallest particle of an element that retains the properties of that element
Atoms can only be seen with proper instrumentation
Dalton’s Atomic Theory wasn’t completely correct
Atoms can be broken down into subatomic particles
Atoms of the same element are not identical

7. Properties of Subatomic Particles

8. Distinguishing Between Atoms

9. Atomic Number
Number of protons in the nucleus of an atom
Identifies the element
Elements are listed on periodic table according to atomic number

10. Atomic Number

11. Atomic Number

12. Atomic Number
atoms are electrically neutral
# protons = # electrons

13. Mass Number
total number of protons and neutrons in an atom
It is not found on the periodic table but can be estimated

14. Shorthand Notation

15. Fill in the following table

16. Isotopes
Atoms that have the same number of protons but different numbers of neutrons
Differ in their mass number

17. Isotopes
the existence of isotopes was not predicted by Dalton, who said atoms of the same element are the same

18. Isotopes
identified by their mass # , write the name of the element then a hyphen with the mass number

19. Isotopes

20. Uses of Isotopes
C-14 = archeological carbon dating
Am-241 = smoke alarms
I-131 = treating thyroid disorder
Co –60 = cancer treatment

21. Atomic Mass (atomic weight)
weighted average mass of the atoms in naturally occurring samples of the element

22. Atomic Mass
reflects the mass and the relative abundance of isotopes as they occur in nature

23. Atomic Mass
To calculate the atomic mass of an element multiply the atomic mass of each isotope of the element by its relative abundance, then add the results
atomic mass = mass1relabd.1 + mass2rel.abd.2+...

24. 1. Calculate the % abundance of fictitious element Nv 2
1. Calculate the % abundance of fictitious element Nv 2. If the mass of 293Nv is amu (red)and that of 295Nv is amu (blue), what is the atomic mass of Nv? .

25. Periodic Table
_______________ was the first person to find a way to list elements in order of increasing atomic mass

26. Periodic Table
He constructed the first periodic table in 1869, an arrangement of the elements according to similarities in their properties.

27. Mendeleev’s Periodic Table

28. Periodic Table
In 1913, ______ determined the atomic number of atoms and arranged the modern periodic table according to atomic number .

29. Modern Periodic Table

30. Modern Periodic Table
Each element is identified by its symbol placed in a square

31. Modern Periodic Table
The horizontal rows of the periodic table are called _____
There are ___

32. Modern Periodic Table

33. Modern Periodic Table
Each vertical column is called a ____ or ____
There are ____.

34. Modern Periodic Table

35. Periodic Table
A periodic law means that physical and chemical properties of elements are functions of their atomic numbers
Elements in the same group on the periodic table have similar properties

36. Modern Periodic Table
Group A elements are called the representative elements because they have a wide range of chemical and physical properties
Name the groups in Group A

37. Modern Periodic Table
Group B elements are called the ______________
The inner transition elements are the ______ and _____

38. Modern Periodic Table

39. Modern Periodic Table
The representative elements can be divided into three broad classes; Metals, Nonmetals, and Metalloids
What are some characteristics of each?

40. Modern Periodic Table

41. Niels Bohr
credited for a model of the atom that states that electrons are at specific distances from the nucleus of an atom

42. Bohr Models
Energy Level 1 2 3 4
# ELECTRONS

43. Bohr Models
Exception: Outermost energy level can only hold up to 8e-
You need to be able to diagram Bohr models for 1-36; excluding transition elements

44. Bohr Models
Do you notice any trends with the group or period of the periodic table?

45. Bohr Models
Trends:
Group numbers (1-8A) predict valence electrons (electrons in the outmost level).
2. The period tells you how many energy levels you have in the atom.