Sinanian Unit 5 CDP

1. 1
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Elements and Our Earth

2. 2
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..And Our Universe

3. Chapter 6 3© 2011 Pearson Education, Inc.
Periodic Trends
• The arrangement of the periodic table means that
the physical properties of the elements follow a
regular pattern.
• We can look at the general trends for the size of
atoms, also known as atomic radius, and their
metallic character:
1. Decrease up a group (or increase down a group).
2. Decrease left to right across a period (or increase right to
left across the period).

4. Chapter 6 4© 2011 Pearson Education, Inc.
Atomic Radius
• Figure 6.4 shows the atomic radii of the main
group elements.
• The general
trend in
atomic radius
applies to the
main group
elements, not
the transition
elements.

5. Chapter 6 5© 2011 Pearson Education, Inc.
Atomic Radius and Metallic Character
•Metallic character is the degree of metal character of an
element and is similar to the trend for atomic radius.
•Metallic character decreases left to right across a period
and from bottom to top in a group.

6. Chapter 6 6© 2011 Pearson Education, Inc.
Physical Properties of Elements
• Since the properties of the elements follow regular
patterns, we can predict unknown properties of
elements based on those around it.
• For example, Table 6.2 lists several properties of
the alkali metals except francium, Fr.
• We can predict the properties of francium based
on the other alkali metals.

7. Chapter 6 7© 2011 Pearson Education, Inc.
Predicting Physical Properties
• We can predict that the atomic radius of Fr is
greater than 0.266 nm, that its density is greater
than 1.87 g/mL, and that its melting point is less
than 28.4 °C.

8. Chapter 6 8© 2011 Pearson Education, Inc.
Predicting Chemical Properties
• Members of a family also have similar chemical
properties.
• All of the alkali metals (Group 1A) have oxides of
the general formula M2O:
– Li2O, Na2O, K2O, Rb2O, Cs2O, and Fr2O.
• Given the formula for the chloride of calcium is
CaCl2, what is the formula for the chloride of
barium?

9. Chapter 6 9© 2011 Pearson Education, Inc.
Predicting Chemical Properties
Since the general formula is MCl2, the formula for barium
chloride must be BaCl2.

10. Chapter 6 9© 2011 Pearson Education, Inc.
Predicting Chemical Properties
Since the general formula is MCl2, the formula for barium
chloride must be BaCl2.