1. Building Blocks of Matter
Atoms
Building Blocks of Matter

2. Atoms Smallest particle of matter to have similar properties
Atoms are particles of an element

3. Subatomic Particles
All atoms are made up of three primary subatomic particles:
Protons
Positively-charged particle in the nucleus
Has a relative mass of 1 Atomic Mass Unit (amu)
Neutrons
Neutrally-charged particle in the nucleus
New theories suggest that Neutrons are slightly larger than Protons, and may be made from a Proton and an Electron that have combined

4. Subatomic Particles Electrons Quarks
Negatively-charged particle outside the nucleus
Has NO relative mass
Actual mass is 1/1936th of 1 amu
Quarks
Smaller particles that make up Protons, Neutrons, and Electrons
Have their own branch of Theoretical Physics

5. Properties of Atoms Atomic Number Atomic Mass
Differentiates between elements
Equal to the number of protons
Atomic Mass
Equal to the number of Nucleons (particles in the nucleus, Protons and Neutrons)

6. Properties of Atoms
Normal atoms are neutral, having the same number of protons and electrons
If an atom gains electrons the atom becomes negatively charged
If an atom loses electrons the atom becomes positively charged

7. NOT ALL OF THESE ARE NECESSARY
Writing Elements
Write the Symbol
Write the Mass Number at the upper-left of the symbol
Write the Atomic Number at the lower-left of the symbol
Any charge goes at the upper-right hand corner
NOT ALL OF THESE ARE NECESSARY +4 Ag
108 47

8. Cl Counting Particles 35 17 Protons = Atomic Number Neutrons =
Atomic Mass – Atomic Number
Electrons = Protons
ADJUST FOR CHARGE
Negative charge means MORE electrons
Positive Charge means LESS electrons Cl 35 17

9. Charge
Atoms will gain, lose, or share electrons to become chemically stable
“Rule of Octet”
Atoms in Groups 1 – 14 will lose electrons down to zero
become positive ions
Atoms in Groups 15, 16, 17, will gain electrons up to eight
become negative ions
Group 18 will not gain, lose, or share electrons
Have 8 electrons anyway

10. Oxidation Number
The number of electrons an atom will gain, lose, or share in order to become stable
The GROUP number indicates the number of outer-shell electrons
Groups 1, 2
Groups (except He)
Always 4 or less
Go with the LOWER number of the two possibilities

11. The Periodic Table Periodic means in a regular, repeating fashion
Many early designs were based on use, physical properties, and even spelling

12. Mendeleev’s Contributions
Organized first working Periodic Table
according to chemical properties and atomic mass
Left gaps for undiscovered elements
He was able to predict many properties of these undiscovered elements based on their location
“Ekasilicon”

13. Periodic Table Rows are called PERIODS
Properties of elements repeat across a Period
Columns are called GROUPS or FAMILIES
Elements in a family have the same Chemical Properties

14. Group 1 Alkali Metals Highly reactive metals
Have one outer shell electron

15. Group 2 Alkaline Earth Metals Reactive metals
Have two outer shell electrons

16. Groups 3 – 12 Transition Metals “normal” metals
Have one to ten outer shell electrons

17. Metals v. Nonmetals METALS Located to the left of the Stair-Step
Lustrous
Malleable & Ductile
Good conductors of heat and electricity
Solid at room temperature (except Hg)
NONMETALS
Located to the right of the Stair-Step
Waxy or dull
Brittle
Poor conductors of heat and electricity (good insulators)
Gas at room temperature (some exceptions)

18. Metalloids May have properties of metals and nonmetals
Located on the stair-step
Some are semiconductors: they only conduct electricity under certain conditions
This makes metalloids excellent switches for computers

19. Group 17 Halogens Highly reactive nonmetals
Means “Salt Former”
Highly reactive nonmetals
Have seven outer shell electrons

20. Group 18 Noble Gases Completely unreactive nonmetals
Will not bond with any atom
Have a full outer shell of electrons
Eight for all but Helium
He has two outer shell electrons

21. Chemical Properties Based on the number of Valence electrons
Electrons on the outside of the atom
Called valence shell electrons, outer shell electrons
Each element in a group has the same number of valence shell electrons
Groups 1, 2 is the group number
Groups 13-18, drop the “1”
Helium has 2
Groups 3-12 use a different set of electrons

22. Drawing a model of an atom
Draw a nucleus
List the number of protons and neutrons in the nucleus
Add energy levels for the number of electrons
An energy level can hold electrons equal to the number of elements in that Period
2, 8, 8, 18, 18, 32, 32

23. Differing Atoms of the Same Element
Isotopes
Atoms of an element with a different number of neutrons
Has the same chemical and physical properties as any other isotope of that element

24. Various Isotopes

25. Differing Atoms of the Same Element
Allotropes
Named when two or more natural or physical forms of an element exists
Ex. for Carbon: Graphite, Diamond, Buckminsterfullerenes
Ex. for Oxygen: O2, O3 - Ozone

26. Allotropes of Carbon

27. Allotropes of Oxygen

28. REVIEW Atoms Elements Subatomic Particles Atomic Number Atomic Mass
Charge
Periodic Table
Mendeleev
Periods
Groups
Families
Metals
Nonmetals
Drawing Atoms
Isotopes
Allotropes