1. Elemental Properties and Patterns
Periodic Trends
Elemental Properties and Patterns

2. Periodic Table
Periodicity: regular variations (or patterns) of properties with increasing atomic number. Both chemical and physical properties vary in a periodic (repeating) pattern.
Group: vertical column of elements (“family”)
Period: horizontal row of elements

3. Periodic Table and Periodicity
Chemistry: The Periodic Table and Periodicity
1. Who first published the classification of the elements that is the basis of our periodic table today?
2. By what property did Mendeleev arrange the elements?
3. By what property did Moseley suggest that the periodic table be arranged?
4. What is the periodic law?
5. What is a period? How many are there in the periodic table?
6. What is a group (also called a family)? How many are there in the periodic table?
DMITRI MENDELEEV
ATOMIC MASS
ATOMIC NUMBER
THE PROPERTIES OF THE ELEMENTS REPEAT PERIODICALLY
A HORIZONTAL ROW IN THE PERIODIC TABLE; 7
A VERTICAL COLUMN IN THE PERIODIC TABLE; 18

4. The Periodic Law Mendeleev understood the ‘Periodic Law’ which states:
When arranged by increasing atomic number, the chemical elements display a regular and repeating pattern of chemical and physical properties.

5. Metals, Nonmetals, & Metalloids1 2
Nonmetals 3 4 5
Metals 6 7
Metalloids
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 349

6. Groups of Elements Transition metals noble gases alkaline earth metals
Elements with similar chemical behavior are in the same group.
noble gases
Transition metals
alkali metals
halogens
alkaline earth metals
lanthanides
actinides

7. Metals
Metals are lustrous (shiny), malleable, ductile, and are good conductors of heat and electricity.
They are mostly solids at room temp.
What is one exception?
Mercury
(Hg)

8. Nonmetals Nonmetals are the opposite.
They are dull, brittle, nonconductors (insulators).
Some are solid, but many are gases, and Bromine is a liquid.

9. Metalloids Metalloids, aka semi-metals are just that.
They have characteristics of both metals and nonmetals.
They are shiny but brittle.
And they are semiconductors.
What is our most important semiconductor?

10. Identifying the patterns
Periodic trends
Identifying the patterns

11. Metallic Characteristics
metallic character increases
metallic character increases
metallic character increases
• Elements with the highest ionization energies are those with the most negative electron affinities, which are located in the upper-right corner of the periodic table.
• Elements with the lowest ionization energies are those with the least negative electron affinities and are located in the lower-left corner of the periodic table.
• The tendency of an element to gain or lose electrons is important in determining its chemistry.
• Various methods have been developed to describe this tendency quantitatively.
• The most important method is called electronegativity (), defined as the relative ability of an atom to attract electrons to itself in a chemical compound.

12. Periodic Table and Periodicity
Chemistry: The Periodic Table and Periodicity
1. Who first published the classification of the elements that is the basis of our periodic table today?
2. By what property did Mendeleev arrange the elements?
3. By what property did Moseley suggest that the periodic table be arranged?
4. What is the periodic law?
5. What is a period? How many are there in the periodic table?
6. What is a group (also called a family)? How many are there in the periodic table?
DMITRI MENDELEEV
ATOMIC MASS
ATOMIC NUMBER
THE PROPERTIES OF THE ELEMENTS REPEAT PERIODICALLY
A HORIZONTAL ROW IN THE PERIODIC TABLE; 7
A VERTICAL COLUMN IN THE PERIODIC TABLE; 18

14. Variable – factor in the experiment that is being tested

15. The factor that is changed is known as the independent variable (IV).
Also referred as “The Cause”
The factor that is measured or observed is called the dependent variable (DV).
Also referred as “The Effect”

16. Rule for Addition and Subtraction Calculating with Numbers Written in Scientific Notation
In order to add or subtract numbers written in scientific
notation, you must express them with the same power of 10.
Sample Problem: Add 5.8 x 103 and x 104
(5.8 x 103) + (21.6 x 103) =
27.4 x 103
2.74 x 104
Exercise: Add 8.32 x and 1.2 x 10-5
1.28 x 10-5

19. Attraction and Repulsion of Electrical Charges+ - + + - -
Particles with opposite
charges attract
one another.
Particles with like charges
repel one another.

20. Coulombic Attraction Depends on: 2+ 2- 2+ 2- 2- 2+ 1+ 1-
1. Amount of charge
2. Distance between charges

21. Periodic Trends atomic radius.
Radius is the distance from the center of the nucleus to the “edge” of the electron cloud.

22. Atomic Radii

23. Atomic Radii Trend: decreases across a period WHY???
As the # of protons in the nucleus increases, the positive charge increases and as a result, the “pull” on the electrons increases.
Trend: increases down a group
WHY???
The atomic radius gets bigger because electrons are added to energy levels farther away from the nucleus decreasing the “pull” or force of attraction.

24. Atomic Size Trends

25. Ionization Energy
Definition: energy required to remove outer electrons from an atom

26. Hungry for Tater Tots?
Mr. C at 7 years old.
Photograph is of me (Mr. Christopherson in 1973, age 7)
Story that goes along with this slide is told in class.

27. OUCH!!
Atoms tend to lose, gain or share electrons to reach a total of eight valence electrons, called an octet.
The octet rule explains the stoichiometry of most compounds in the s and p blocks of the periodic table.
Number eight corresponds to one ns and three np valence orbitals, which together can accommodate a total of eight electrons.

28. Ionization Energy Trend: decreases down a group WHY???
Trend: increases across a period
WHY???
All the atoms in the same period
Increasing the number of protons increase the “pull” or force of attraction.
Trend: decreases down a group
WHY???
Electrons are further away from the positive “pull” of the nucleus and therefore easier to remove.

29. First Ionization energyHe Ne Ar Kr H Li Na K Rb
First Ionization energy
Atomic number

30. Electronegativity
Definition: the tendency of an atom to attract electrons to itself when chemically combined with another element

31. Electronegativity Trend: increases across a period
(noble gases excluded!)
WHY???
Nuclear charge is increasing, atomic radius is decreasing; attractive force that the nucleus can exert on another electron increases.
Trend: decreases down a group
WHY???
The electrons are farther away from the nucleus; decreased attraction, so decreased electronegativity

32. ElectronegativityTrends

33. Summing Up Periodic Trends

34. Summing Up Periodic Trends
Increasing ionization energy
Increasing Ion radius

35. Which has the largest atomic radius?
Br- Br
8. Al Al
As an atom gains electrons, the atom gets bigger
As an atom loses electrons, the atom gets smaller