1. Chemical Periodicity

4. In 1869, Dimitri Mendeleev arranged all of the known elements in order of increasing atomic mass and chemical properties of the atoms. He found a pattern that exists and is repeated, or is periodic, in all the elements. *

5. Henry Moseley’s modern periodic table is arranged in order of increasing atomic number and would look like this if we didn’t move the rare earth elements to below

6. The Periodic Law
The periodic law: When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.
The properties of the elements within a period change as you move across a period from left to right.
The pattern of properties within a period repeats as you move from one period to the next. *

7. Searching For an Organizing Principle
Chlorine, bromine, and iodine have very similar chemical properties.
Chlorine, bromine, and iodine have very similar chemical properties. The numbers shown are the average atomic masses for these elements. *

8. Isoelectronic Ions with the same electronic configuration as a noble gas are said to be isoelectronic with a noble gas.

9. Valance e- are in the outer orbit
The pattern exists because there is a pattern in the valance electrons.
The pattern is…
Atoms in the 1st column have 1 valance e-
“ nd “ valance e-
“ rd “ valance e-
Valance e- are in the outer orbit
They are responsible for the atoms chemical & physical properties
Atoms are most stable when their outer orbit is either completely full or empty. *

10. Periodic - repeats according to a pattern
Patterns on the p chart are caused by patterns in the e- configurations s 1
1st
Highest orbital
# of e-
Group s 2
2nd p 1
3rd p 2
4th p 3
5th p 4
6th p 5
7th p 6
8th
The atoms in the 8th column have full energy levels (noble gasses)

11. Thus, all elements in a column have similar prop.
The valence e- are responsible for the elements chemical and physical properties
Ex)
Li 1s22s1
Na 1s22s22p63s1
K 1s22s22p63s23p64s1
Notice that there is only 1 e- in the outermost orbital
(They all have one valence e-)
Thus, all elements in a column have similar prop.

12. Major Regions of the Periodic Table

13. What’s on the periodic table?
Metals
Alkali Metals
Alkaline Earth Metals
Transition Metals
Non-metals
(To the right of the “zig-zag” line)
*polyatomic nonmetal
*noble gases
*halogens
Metaloids
Touch the “zig-zag” line

14. Metals Left of “zig-zag” line Metals are… Shiny luster Malleable
Ductile
Good conductors
Heat & Electricity
Lose their e-
All of these properties result from
loosely held valence electrons in metals *

15. P
Metals *

16. Non-metals Right of the “zig-zag” line Non-metals are…
Usually gas at room temp.
Brittle
Dull
Poor conductors
Gain e-
Typically gain e-1
All of these properties result from more
tightly held valence electrons in nonmetals *

17. TOP
Non-Metals *

18. Metalloids Touch the line Solids at room temperature
Sometimes they act like metals, sometimes they act like non-metals - it depends on the conditions such as temp and pressure
Semi-conductors of electricity
Silicon *

19. P *

20. Important Families of the Periodic Table

21. Alkali Metals The most reactive metals
Never found alone, always in a compound
Like to form + ions b/c they tend to lose 1 e- to become stable *

22. Alkaline Earth Metals Reactive, usually produce a base
Always found in a compound
Like to lose 2 e- *

23. Transition Metals
Properties of metals
Not very reactive

24. Transition ElementsThe “Group B” elements are displayed in the main body of the periodic table. They have electrons in d sublevels and are all classified as metals. Inner Transition Metals are found within the Transition Metals and contain electrons in f sublevels

25. Boron Family Carbon Family Nitrogen Family Oxygen Family
Likes to lose 3 e-
Carbon Family
Will lose or gain 4 e-
Nitrogen Family
Gains 3 e-
Oxygen Family
Gains 2 e- *

26. Halogens Gains 1 e- Very reactive, used for killing germs
Whenever a metal and a halogen combine, they form a “salt” *

27. Noble Gases
Very unreactive
Their outer orbit is full

28. Periodic Trends
Periodic Trends

29. Trends on the periodic table:
Atomic radius - size of the atom
Ionization energy - energy required to steal an e-
Electronegativity - tendency for the atom to attract e- when chemically combined with another atom

30. Atomic Radius: ↓ Increases → Decreases Ionization energy: ↓ Decreases
Summary of Periodic Trends
Atomic Radius:
↓ Increases
→ Decreases
Ionization energy:
↓ Decreases
→ Increases
Electronegativity:
↓ Decreases
→ Increases
2. Ionic Radius:
Cation:
Radius Decreases
Anion:
Radius Increases

31. Atomic radius atomic radius decreases smallest atom atomic radius
increases
largest
atom
Which is larger?
1. N or P Al or Si Na or Cs N or O

32. How is radius determined?
Why can’t we just measure the radius of one atom?

35. Ions
Positive and negative ions form when electrons are transferred between atoms.
When a sodium atom loses an electron, it becomes a positively charged ion. When a chlorine atom gains an electron, it becomes a negatively charged ion. Interpreting Diagrams What happens to the protons and neutrons during these changes? *

36. Ions
Positive and negative ions form when electrons are transferred between atoms.
When a sodium atom loses an electron, it becomes a positively charged ion. When a chlorine atom gains an electron, it becomes a negatively charged ion. Interpreting Diagrams What happens to the protons and neutrons during these changes? *

37. Ionic radius: Which is larger? S or S2– K+1 or K
cations: smaller than their parent atoms
anions: larger than their parent atoms
follows same pattern as atomic radius
Which is larger?
S or S2– K+1 or K
Na+1 or Mg Mg2+ or Ca2+

39. Trends in Ionization Energy
The energy required to remove an electron from an atom is called ionization energy.
The energy required to remove the first electron from an atom is called the first ionization energy.
The energy required to remove an electron from an ion with a 1+ charge is called the second ionization energy. *

40. Ionization energy: B or C Zn or Ga Na or K K or Ca Mg or Al B or Al
I.E.
increases
highest
I.E.
I.E.
increases
lowest
I.E.
Which has the higher ionization energy?
B or C Zn or Ga Na or K
K or Ca Mg or Al B or Al

42. Trends in Electronegativity
Electronegativity is the ability of an atom of an element to attract electrons when the atom is in a compound.
In general, electronegativity values decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a period. *

43. Electronegativity: B or C Zn or Ga Na or K O or F P or N F or Cl
Electro. increases
highest
electro.
Electro. increases
lowest
electro.
Which has the higher electronegativity?
B or C Zn or Ga Na or K
O or F P or N F or Cl

44. Trends in Electronegativity
6.3
Trends in Electronegativity
Representative Elements in Groups 1A through 7A *