Chapter 3: Chem I

1
The Periodic Table

• Chapter 3 Chem I
• Chapter 6 ChemIH

2
History

• 1800s- 60 known elements their atomic masses
• 1829 - Döbereiners Triads (groups of 3)
• Some elements grouped in 3s by their properties
• Physical properties of the middle element usual
  about ½ way between those of the other 2
  elements.
• Ex Halogen Triad Cl, Br, I (see Table 3.1, p
  87)

3
Döbereiner Triads

• Halogen Triad Cl, Br, I
• Alkali Triad
• Li 7 g
• Na ?
• K 39 g
• Coinage Metals Triad Cu , Au, Ag

4
History (cont.)

• 1869- Dmitri Mendeleev noticed that properties of
  elements repeated in an orderly way when
  organized by atomic mass. This is periodicity.
• He put them in order from lightest to heaviest
  (atomic mass) grouped them when properties
  repeated themselves. (see Table 3.3 on p 90 of
  text)

5
History, cont.

• Even though Mendeleev couldnt identify Zn, Si,
  and Ca, he was able to predict
• their existence and
• their behavior!

6
Modern Periodic Table

• Elements placed in order of increasing atomic
  number.
• Noble gases have been added
• Synthetic elements too

7
Using the Periodic Table

• (Review)
• Groups
• Group for Main Group Elements indicates the
  of v.e-s
• Elements in a group have similar chemical
  properties b/c the of v.e-s is the same (AND
  VALENCE ELECTRONS DETERMINE CHEMICAL REACTIVITY!)
• Periods
• Period indicates the energy level of the v.e.-s

8
Using the Periodic Table, cont.

• (New Info)
• Periods
• Each period ends with a Noble Gas
• Each period ends with
• a full s sublevel (___ v.e.-s) OR
• full s p sublevels (___ v.e.-s)

9
Using the Periodic Table, cont.

• Group Names
• Group 1 Alkali Metals
• Group 2 Alkaline Earth Metals
• (Group 16 Chalcogens)
• Group 17 Halogens
• Group 18 Noble Gases

10
Physical States of the Elements

• The P. Table shows the state of the elements at
  room temperature.
• Most elements are solid
• Some elements are gas (most on right side of P
  Table. Only H is on left.)
• 2 elements are liquid (Br Hg)

11
3 Classes of the Elements Common Properties
Metals Nonmetals Metalloids
Uses Vehicles, jewelry, coins, wires, computers Abundant in nature-fuels, living tissue, Computer chips,
Examples Na, Ca, Ti, Cr, Fe, Cu, Ag, Zn, Pt, U H, He, C, N, O, F, I (most are gases) B, Si, Ge, As, Sb, Te, Po, At
Color Silvery luster (shine) Various
Conductive (heat electricity) Very No Poor to fair
Malleable Yes No-Brittle, when solid Often brittle
Ductile Yes No- No
Groups 1-12, most of 13, transition elements inner transition elements H, 1 in Group 14 2 in Group 15 3 in Group 16 4 in Group 17 All of Group 18 Groups 13-17, only 1-2 elements in ea group
of v.e.-s 1, 2, 3, Sn Pb (4 v.e.-s), Bi (5 v.e.-s) (4), (5), (6), 7 8 3-7
Behavior of v.e-s Loosely held-tend to lose them Tightly held-tend to share or gain them Moderately held-tend to share
12
Metalloids

• Metalloids are often called semiconductors.
• They conduct heat electricity, but poorly
• This is good in computers b/c they dont
  overheat.
• Doping is used to make them better conductors.

13
Metalloids Doping

• Have an electron arrangement that keeps them from
  moving freely.
• Ex each germanium atom (Ge) has 4 v.e.-s it
  shares with 4 neighboring Ge atoms.
• This creates a stable lattice, in which e-s are
  spaced evenly throughout the Ge, so they dont
  move

14
Metalloids Doping

• Doping- If you place an occasional atom of
  another element, In or As, among the Ge atoms,
  you increase the movement of the e-s

15
2 Types of Doping

• 1. n-type (negative type) creates a shortage
  of e-s, in some areas, so they move to try to
  even out the charges

Indium has 3 v.e.-s, so in the lattice, there are
holes- areas missing an e-
16
2 Types of Doping, cont.

• 2. p type creates an excess of e-s in some
  areas, so they move to try to even out charges