Transcript Chapter 3: Intro To the Periodic Table

The Periodic Table
Chapter 3: Chem I
Chapter 6 ChemIH
History
 1800’s- 60 known elements + their atomic
masses
 1829 - Döbereiner’s Triads (groups of 3)
 Some elements grouped in 3’s 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)
Döbereiner Triads
 Halogen Triad: Cl, Br, I
 Alkali Triad:
 Li = 7 g
 Na = ?
 K = 39 g
 Coinage Metals Triad: Cu , Au, Ag
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)
History, cont.
Even though Mendeleev couldn’t
identify Zn, Si, and Ca, he was able
to predict
 their existence and
 their behavior!
Modern Periodic Table
Elements placed in order of
increasing atomic number.
Noble gases have been added
Synthetic elements too
Using the Periodic Table
(Review)
 Groups
o Group # for Main Group Elements indicates
the # of v.e-s
o 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
o Period # indicates the energy level of the v.e.-s
Using the Periodic Table, cont.
(New Info)
 Periods
oEach period ends with a Noble Gas
 Each period ends with
oa full s sublevel (___ v.e.-s) OR
ofull s & p sublevels (___ v.e.-s)
Using the Periodic Table, cont.
Group Names
oGroup #1: Alkali Metals
oGroup #2: Alkaline Earth Metals
o(Group #16: Chalcogens)
oGroup #17: Halogens
oGroup #18: Noble Gases
Physical States of the Elements
The P. Table shows the state of the
elements at room temperature.
oMost elements are solid
oSome elements are gas (most on
right side of P Table. Only H is on
left.)
o2 elements are liquid (Br & Hg)
3 Classes of the Elements:
Common Properties
Metals
Nonmetals
Metalloids
Uses
Vehicles, jewelry, coins,
wires, computers
Abundant in naturefuels, 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, +
H, 1 in Group 14
transition elements
2 in Group 15
inner transition elements 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)
3-7
(4), (5), (6), 7 & 8
Metalloids
 Metalloids are often called
semiconductors.
 They conduct heat & electricity, but
poorly
 This is good in computers b/c they
don’t overheat.
 Doping is used to make them better
conductors.
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
don’t move
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
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-
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