1. The Periodic Table
Ch 6 CVHS Chemistry EQ: How do electron configurations relate to the periodic table?

2. Modern Periodic Table Organized by Atomic Number, not Atomic mass
Atomic # = protons
Atomic # increases as you move across
Each row (except the first) begins with a metal and ends with a noble gas
The properties of elements change in an orderly progression from left to right: periodicity
The pattern in properties repeats after column 18

3. Periodic Law
The statement that the physical and chemical properties of the elements repeat in a regular pattern when they are arranged in order of increasing atomic number is known as the periodic law
Atomic radius decreases as you move across the table.

4. Atomic Structure & Periodic Table
As atomic # increases across the periodic table so do the # of electrons
The chemical behavior of the elements is determined by the number of electrons in their valence shell (s & p sublevels).

5. Atomic Structure & Periodic Table
Groups or families
Vertical columns, have same valence electrons
Periods
Horizontal rows, atomic # increases by one as you go across
Valence Electrons
The electrons in the outermost s & p sublevels.
Available for reacting
Elements take or release electrons to make their outermost shell stable.

6. Atomic Structure of elements w/in a period
1st period complete w/ 2 elements, H & He b/c 1st energy level can only hold 2 electrons
How many valence electrons are found in H & He & S?
H: 1 (1s1)
He: 2 (1s2)
S: 6 (3s2 3p4)

7. Atomic Structure w/in a group
The number of valence electrons changes from one to eight as you move from left to right across a period; when you reach Group 18, the pattern repeats.
The main group elements have the number of valence electrons equal to their group number.
Group 1 = 1
Group 2 = 2
Group 3A (13) = 3
Group 4A (14) = 4

8. Atomic Structure w/in a group
Elements in the same group have the same # of valence electrons so they have similar properties
Group 1: 1 valence electron
Group 17: 7 valence electrons
Valence electrons are always s & p sublevel electrons: WHY?

9. Commonly Used Group Names
Alkali metals in Group 1
Form bases w/ non metals Alkali means basic
Alkaline earth metals in Group 2,
Halogens in Group 17
Means salt, b/c they form saltlike compounds w/ metals
Noble gases in Group 18
Don’t tend to react

10. Element Classification
Elements are classified on the basis of their physical and chemical properties
Metals
Nonmetals
Metalloids

11. Metals
Luster, conduct heat & electricity & bend, most are solids @ room temp w/ high melting points, typically not main group elements
Groups 1 & 2 are metals & some of groups are metals
Groups 3-12 are transition elements, all are metals
Inner Transition Elements (58-71 & ), all are metals

12. Nonmetals
Don’t conduct electricty, poor conductors of heat, low melting points, most are gases, solids lack luster, solids are brittle
Have 5, 6, 7 or 8 valence electrons (except C has 4)
Abundant in nature
Carbon found in more compounds than any other elements

14. Metalloids Have some properties of metals & nonmetals
Found on border between metals & nonmetals
Some metalloids such as silicon, germanium (Ge), and arsenic (As) are semiconductors
They conduct electricity better than a nonmetal but not as well as a metal
Si made the computer industry possible.

15. Metals, Nonmetals, Metalloids

16. Periodic Trends Atomic Radius Measure of the size of an atom
Decreases as you move across the table
More protons in the nucleus pull the electrons toward the center of the atom
Increases as you move down the table
Same # of valence electrons farther away from the nucleus & they are shielded by the inner shell electrons

17. Ionic Radius Atoms who gain or lose electrons are ions
Cations: lose electrons, have postive charge
Ionic radius decreases
Anions: gain electrons, have negative charge
Ionic radius increases
Both still decrease in size moving across and increase in size moving down

18. Metals Metalloids Nonmetals
Concept Check: Complete the Venn & describe how each concept fits into the periodic table.
Metals
Metalloids
Nonmetals