1. Properties of Elements and Trends
The Periodic Table
Properties of Elements and Trends

2. Mendeleev The original periodic table was created by Dmitri Mendeleev.
He organized the table by atomic mass.
He predicted existence of 3 missing elements (Ga, Sc, Ge)

3. Modern Periodic Table
The modern periodic table is organized by atomic number.
Henry Mosely

4. Vertical columns  called groups or families
Horizontal rows  called periods also represent the shells or energy levels
The basis of periodic law is repeating patterns.

5. Major Categories of Elements
1) metals 2) non-metals 3) metalloids
Metals are found to the left of the “staircase”
Non-metals are found to the right of “staircase”
Metalloids are found “on” the staircase

7. Properties of Metals Solid at room temperature (except Hg)
Shiny, Have luster
Malleable
Ductile
Generally have high melting points
Good conductor of heat and electricity
Have metallic bonds

8. Properties of Non-metals
Can be solid, liquid or gas at room temp
S  examples C, S, I2
L  Br2
G  O2, Ne, F2
Allotropes- different molecular forms of the same element (different properties, too) O2 and O3
Dull, lack luster
Brittle
Poor conductors

9. Properties of Metalloids
Solid at room temperature
Semi-conductors
Have varying properties that can be metallic or non-metallic

10. Metals tend to lose electrons to form a full valence shell and + ions.
Non-metals tend to gain electrons to form a full valence shell and – ions.

11. Groups on the Periodic Table
In general, elements found within the same group have similar chemical and physical properties.
This is mainly due to the fact that they have the same number of valence electrons.

12. Alkali Metals (Group I)
Have one valence electron
Tend to lose that one electron to become a more stable ion.
Rarely found in natural state.

13. Lithium(Li), Sodium(Na), and Potassium(K)
Three examples of alkali metals
VERY reactive metals
Exist as solids at room temperature, but are soft
Silvery-white or grayish in color

14. Lithium

15. Sodium

16. Potassium

17. Alkaline Earth Metals (Group II)
Have two valence electrons
Tend to lose the two electrons to become a more stable ion

18. Magnesium(Mg), Calcium(Ca) and Strontium(Sr)
Examples of alkaline earth metals
Exist as solids at room temperature
Silvery white or grayish white in color
Fairly reactive metals

19. Magnesium

20. Calcium

21. Strontium

22. Halogens Group 17 Have 7 valence electrons Non-metals (F, Cl, Br, I)
F, Cl (gases), Br (liquid), I (solid)
Tend to gain one electron to form a more stable ion
Extremely reactive

23. Fluorine

24. Chlorine

25. Noble Gases Group 18 Very stable because of filled valence shell.
Do not react in the presence of other elements (relatively inert)
Xe can react with Fluorine (more later)

26. Argon

27. Xenon
Used in UV lamps and sun lamps in tanning salons.

28. Transition Metals Also known as “heavy metals” Tend to be very dense
Have varying reactivity
Have multiple oxidation states (can form more than one ion)
Have colorful ions (in solution)

29. Copper

30. Nickel

31. Silver

32. Lanthanide and Actinide Series
Rare earth metals
Above 92 they are mostly man-made and are unstable

33. Periodic Trends
Trends occur in the periodic table in the following areas:
-reactivity
-metallic/non-metallic character
-atomic radius*
-ionization energy*
-ionic radius
-electronegativity*

34. Period Trends in Atomic Radius
Atomic radius decreases

35. Ionization Energy
The energy required to remove an electron from an atom is known as the FIRST IONIZATION ENERGY.
To remove a second electron requires what is called the SECOND IONIZATION ENERGY.

36. Cation Size MINUS ONE ELECTRON
When an electron is lost from an atom, the nucleus now has more pull on the outer energy level making the ion SMALLER.
MINUS ONE ELECTRON

37. Anion Size PLUS ONE ELECTRON
When an electron is gained the nucleus now has less pull on the outer energy level making the ion LARGER.
PLUS ONE ELECTRON

38. Electronegativity
Can be defined as an atom’s ability to attract electrons.
Expressed in arbitrary units on Table S of your Reference Tables.
Non-metals tend to have higher electronegativities because they like to gain electrons.
atoms
electrons