1. Chapter 6 The Periodic Table
Ms. Wang
Lawndale High School

2. Section 6.1 - Organizing the Elements
By the 1700’s, only about 13 elements had been identifies
Chemists used the properties of elements to sort them into groups
In 1829, J.W. Dobereiner published a classification system with elements grouped into set of three based upon similar chemical properties

3. Mendeleev’s Periodic Table
From 1829 to 1869, many different systems were proposed, but none gained wide acceptance
In 1869, Dmitri Mendeleev arranged the elements in his periodic table in order of increasing atomic mass, based upon repeating properties

4. The Periodic Law
In the modern periodic table, elements are arranged in order of increasing atomic number
Periodic Law – when elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties

5. Metals, Metalloids and Nonmetals (Red ladder on the periodic table)
Elements can be grouped into three broad classes based on their general properties
Metals
Nonmetals
Metalloids

6. Metals: elements that are generally solid at room temperature, have a grayish color and shiny surface, and conduct heat and electricity
Nonmetals: elements that have varying properties but are generally poor conductors of heat and electricity
Metalloids: elements with some properties of metals and and nonmetals

7. Section 6.2 - Classifying the Elements (Page 162-163)
The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms
Element symbols that are printed in black are solid at R.T., blue are liquid at R.T., and red are gasses at R.T.
Some elements are printed in green, which means that they are not found in nature

8. The 7 Groups of the Periodic Table
Alkali Metals (Group 1A)
Alkaline Earth Metals (Group 2A)
Chalcogens (Group 6A)
Halogens (Group 7A)
Noble Gases (Group 8A)
Transition Metals (Group B)
Inner Transition Metals (Lanthanides and Actinides)

9. Electron Configurations in Groups
Elements can be sorted into noble gases, representative elements, transition metals, or inner transition meals based on their electron configuration
Noble Gases always have their s and p sublevels completely filled with electrons, which makes them relatively inactive

10. Representative Elements
Representative Elements are Groups 1A through 7A because they display a wide range of physical and chemical properties
For any representative element, its group number always equals the number of electrons in the highest occupied energy level (Valence Shell)

11. Transition Metals
Transition Metals are characterized by the presence of electrons in the d orbital
Inner Transition Metals are characterized by the presence of electrons in the f orbital

12. Section 6.3 – Periodic Trends
Properties of elements are related to the location of elements in the periodic table
Four periodic trends:
Atomic Radius
Ionization Energy
Electron Affinity
Electronegativity

13. 1. Atomic Radius
One-half of the distance from center to center of two atoms of the same element
Atomic Radius

14. 1. Atomic Radius
What do you notice about the atomic radii of the elements on the periodic table?

15. Atomic Radius Practice
Which element has a greater atomic radius?
F or Cs
Ga or K
Kr or Rb
Put these elements in order of increasing atomic radius
Ba, Si, Fr, W, O, Ag

16. Ions
Remember that atoms that are electrically neutral have equal number of protons and electrons
Some compounds are composed of particles called ions.
Ions are atoms that have a positive or negative charge.

17. Ions
Positive and negative ions form when electrons are transferred between atoms
Cation – an ion with a positive charge
Anion – an ion with a negative charge

18. 2. Ionization Energy
The energy required to remove an electron from an atom - +
Lithium Ion
Lithium atom

19. 2. Ionization Energy
Elements with low ionization energy are good conductors of electricity

20. 2. Ionization Energy
What trend do you notice about the ionization energy of the elements on the periodic table?

21. Ionization Energy Practice
Which of these elements has a greater ionization energy?
Ar or Kr
Al or Na
S or Rb
Put these elements in order of increasing ionization energy
Si, Cs, He, Ca, P, O

22. Ionic Size
Cations are always smaller than the atoms from which they form
Anions are always larger than the atoms from which they form
WHY? (Hint: think about the electron cloud of an atom)
Which is larger? Na or Na+, Al or Al3+, I or I-, S or S2-

23. 3. Electron Affinity
What trend do you notice about the electron affinity of the elements on the periodic table?

24. 4. Electronegativity
The tendency of an atom to attract electrons to itself when in a compound

25. 4. Electronegativity
What trend do you notice about the electronegativity of the elements on the periodic table?

26. Electronegativity Practice
Which element has greater electronegativity?
Na or F
Ca or C
Al or Mg
Put these elements in order of increasing electronegativity
Sr, Al, Ca, K, Cl, F

27. Chapter 6 Assessment (Page 181)
Homework
Chapter 6 Assessment (Page 181)
#’s 26-46, 48, 49, 52, 64