Download 5.3 Representative Groups PPT

DO NOW:
2/25/14
n 
Take out your 5.2 HW Questions & Ch. 5 Notes
n 
On Do Now Sheet (write answer in a complete
sentence)
1.  Compare how did Mendeleev organize the
elements in his periodic table to how the
elements are organized in the modern periodic
table.
2. 
2/25/14
Elements that start off each row also start off
each of the 7 main ______________________.
Chapter 5: The Periodic Table
1
5.3 REPRESENTATIVE GROUPS
n 
Vocabulary: valence electron, alkali metals, alkaline
earth metals, halogens, noble gases
n 
Objectives:
n  Relate the number of valence electrons to groups
in the periodic table and to properties of elements
in those groups.
n  Predict the reactivity of some elements based on
their locations within a group.
n  Identify some properties of common A group
elements.
2/25/14
Chapter 5: The Periodic Table
2
2/25/14
Chapter 5: The Periodic Table
3
VALENCE ELECTRONS
n 
n 
2/25/14
2 numbering schemes
A Groups
n  numbered 1- 8
n  # matches # of valence electrons in electron
configuration for element in that group
Chapter 5: The Periodic Table
4
VALENCE ELECTRONS
n 
valence electron - electron that is in the highest
occupied energy level of an atom
n  key role in chemical reactions
Na
n 
2/25/14
Mg
Al
Si
properties vary across a period b/c the # of
valence electrons increases left à right
Chapter 5: The Periodic Table
5
VALENCE ELECTRONS
n 
electron configuration determines an
element s chemical properties & therefore
elements within the same group have similar
chemical properties (from 5.2)
n 
elements in a group have similar properties
because they have the same # of valence
electrons
2/25/14
Chapter 5: The Periodic Table
6
Li
VALENCE
ELECTRONS
Na
properties will not be identical
because valence electrons are
in different energy levels
K
Rb
Cs
2/25/14
Fr
Chapter 5: The Periodic Table
7
VALENCE ELECTRONS
HYDROGEN QUESTION:
n 
2/25/14
If hydrogen is a nonmetal gas that seems to
have more in common with Group 17
nonmetals than Group 1 metals, why is it
located on the left side of the periodic table
with the active metals?
Chapter 5: The Periodic Table
8
VALENCE ELECTRONS
HYDROGEN ANSWER
n 
hydrogen s location is related to its
electron configuration & # of valence
electrons, not its properties
n 
2/25/14
has 1 valence electron so it is grouped
with other elements that have only 1
valence electron
Chapter 5: The Periodic Table
9
GROUP 1A:
THE ALKALI METALS
2/25/14
n 
1 valence electron
n 
properties: extremely reactive
n 
found in nature only in compounds
n 
example: table salt NaCl
Chapter 5: The Periodic Table
10
GROUP 1A: THE ALKALI METALS
lithium
Least
Reactive
sodium
the reactivity of
alkali metals increases
from the top of
Group 1A to the bottom
potassium
rubidium
cesium
francium
2/25/14
Most
Reactive
Chapter 5: The Periodic Table
11
GROUP 1A: THE ALKALI METALS
What properties of sodium are shown
in the photos?
2/25/14
Chapter 5: The Periodic Table
12
GROUP 1A: THE ALKALI METALS
n 
2/25/14
Sodium
n  soft (unlike most metals)
n  melting point: 98°C
n  density < water
n  reacts with water à
n  hydrogen gas produced
n  enough energy released
to ignite the hydrogen
gas
Chapter 5: The Periodic Table
13
GROUP 1A: THE ALKALI METALS
DID YOU KNOW?
n 
2/25/14
Francium
n 
most unstable of the 1st 103
elements
n 
longest lived isotope,
francium-223, has a half-life
of only 22 minutes
n 
only about one ounce of
francium on Earth at any
moment
Chapter 5: The Periodic Table
14
GROUP 2A:
THE ALKALINE EARTH METALS
Beryllium No change when
added to water.
Least
Reactive
Magnesium reacts with hot
water
Calcium -
n 
valence electrons: 2
n 
properties: metals;
harder than metals in
Group 1A
n 
differences in reactivity
among the alkaline
earth metals are shown
by the way they react
with water
reacts easily with
cold water
Strontium reacts easily with
cold water
Barium reacts easily
with cold water
Radium
2/25/14
Most
Reactive
Chapter 5: The Periodic Table
15
THE ALKALINE EARTH METALS:
MAGNESIUM & CALCIUM (Pg 141)
n 
magnesium & calcium have essential
biological functions & provide materials used
in construction & transportation
n 
Mg: helps plants produce sugar & can be used
to make light weight bicycle frames
n 
Ca: helps build strong
teeth & bones & is the
main ingredient in limestone
2/25/14
Chapter 5: The Periodic Table
16
GROUP 3A:
THE BORON FAMILY
2/25/14
n 
valence electrons: 3
n 
glass containing boron used in lab
glassware & some cookware
n 
aluminum is the most abundant metal in
Earth s crust
n  often combined with O
in mineral called bauxite
n  strong, lightweight,
malleable, & good conductor
Chapter 5: The Periodic Table
17
GROUP 4A
THE CARBON FAMILY
Carbon
Least
n  valence electrons: 4
Metallic
n 
properties: metallic nature
of elements increases
from top to bottom within
group. 1 nonmetal, 2
metalloids, 2 metals
n 
except for water, most
compounds in your body
contain carbon
n 
silicon 2nd most abundant
element in Earth s crust
Silicon
Germanium
Tin
Lead
2/25/14
Most
Metallic
Chapter 5: The Periodic Table
18
GROUP 5A:
THE NITROGEN FAMILY
n 
valence electrons: 5
n 
properties: Wide range of physical
properties
n 
besides nitrogen,
fertilizers often contain
phosphorus
2/25/14
Chapter 5: The Periodic Table
19
GROUP 6A:
THE OXYGEN FAMILY
2/25/14
n 
valence electrons: 6
n 
oxygen
n  most abundant element in Earth s crust
n  ozone is form of oxygen
n 
sulfur
n  1 of 1st elements
discovered
n  large natural deposits
Chapter 5: The Periodic Table
20
GROUP 7A
THE HALOGENS
2/25/14
n 
valence electrons: 7
n 
properties: highly reactive nonmetals (&
metalloid); reacts easily with most
metals
n 
despite their physical differences, the
halogens have similar chemical
properties
Chapter 5: The Periodic Table
21
GROUP 8A
THE NOBLE GASES
2/25/14
n 
valence electrons: 8
n  helium has 2 valence electrons
n 
properties: colorless & odorless &
extremely unreactive nonmetals
n 
can be very useful
n  used to prevent reactions with such
highly reactive elements as oxygen.
Chapter 5: The Periodic Table
22
2/25/14
Chapter 5: The Periodic Table
23
2/25/14
Chapter 5: The Periodic Table
24
2/25/14
Chapter 5: The Periodic Table
25
LINKS
n 
David s Wizzy Periodic Table - Click on Element to See
Atom Structure.
http://www.colorado.edu/physics/2000/applets/a2.html
n 
Interactive Periodic Table of Elements.
http://www.webelements.com/
http://www.chemicool.com/ http://web.visionlearning.com/
custom/chemistry/custom/CHE1.4-pg-table.shtml
2/25/14
Chapter 5: The Periodic Table
26
LINKS
Alkali & Alkali Earth Metals
http://www.youtube.com/watch?v=DFQPnHkQlZM
http://www.youtube.com/watch?v=uixxJtJPVXk
http://www.youtube.com/watch?v=eaChisV5uR0
http://www.youtube.com/watch?v=kyLPS3EHS8M
http://www.youtube.com/watch?v=JSUhzcVnuOg
http://www.youtube.com/watch?v=MGUPKA_pOEE
n  Comparing 4 Halogens
http://www.youtube.com/watch?v=u2ogMUDBaf4
http://www.youtube.com/watch?v=m0RAE8j6sjY
http://vimeo.com/55688451
n  Brainiac Video
http://www.youtube.com/watch?v=83eq5HyG-tI
http://www.teachertube.com/viewVideo.php?video_id=41344
n 
2/25/14
Chapter 5: The Periodic Table
27