1. The Periodic Table of the Elements
Ch 15
Representative and Transition Elements

2. Development of the Periodic Table
In 1830, 55 different elements had been isolated and named-the list is still growing

3. Development of the Periodic Table
Dmitri Mendeleev- Russian Chemist published the first version of the Periodic Table in 1869
Arranged the elements by their atomic mass
Recognized patterns-elements with similar properties fell into groups
Left gaps for missing elements
Made predictions for the properties of missing elements

4. Today’s Periodic Table

5. Families Periods Columns of elements are called groups or families.
Elements in each family have similar but not identical physical and chemical properties.
For example, lithium (Li), sodium (Na), potassium (K), and other members of family IA are all soft, white, shiny metals.
All elements in a family have the same number of valence electrons.
Each horizontal row of elements is called a period.
The elements in a period are not alike in properties.
In fact, the properties change gradually and predictably across even given row.
The first element in a period is always an extremely active solid. The last element in a period, is always an inactive gas.

9. Properties of Metals good conductors of heat and electricity. shiny.
ductile (can be stretched into thin wires).
malleable (can be pounded into thin sheets).
A chemical property of metal is its reaction with water which results in corrosion.

10. Properties of Non-Metals
Poor conductors of heat and electricity.
Not ductile or malleable.
Solid non-metals are brittle and break easily.
Dull
Many are gases.
Sulfur

11. Properties of Metalloids
Metalloids (metal-like) have properties of both metals and non-metals.
Solids that can be shiny or dull.
Conduct heat and electricity better than non-metals but not as well as metals.
Ductile and malleable.
Silicon

12. The most abundant element in the earth’s crust is oxygen.

13. Key to the Periodic Table
Elements are organized on the table according to their atomic number, usually found near the top of the square.
The atomic number refers to how many protons an atom of that element has.
For instance, hydrogen has 1 proton, so it’s atomic number is 1.
The atomic number is unique to that element. No two elements have the same atomic number.

14. What’s in a square?
Different periodic tables can include various bits of information, but usually:
atomic number
symbol
atomic mass
number of valence electrons
state of matter at room temperature.

15. C Cu Symbols Carbon Copper All elements have their own unique symbol.
It can consist of a single capital letter, or a capital letter and one or two lower case letters. C
Carbon Cu
Copper

16. Atomic Mass and Isotopes
While most atoms have the same number of protons and neutrons, some don’t.
Some atoms have more or less neutrons than protons. These are called isotopes.
An atomic mass number with a decimal is the total of the number of protons plus the average number of neutrons.

17. Atomic Mass Unit (AMU)
The unit of measurement for an atom is an AMU. It stands for atomic mass unit.
One AMU is equal to the mass of one proton.

18. Atomic Mass Unit (AMU) There are
6 X 1023 or 600,000,000,000,000,000,000,000 amus in one gram.
(Remember that electrons are 2000 times smaller than one amu).

19. Groups 1 and 2 Always found in nature combined with other elements
Active metals
Readiness to form new substances
All metals except hydrogen

20. Group 1-Alkali Metals Silvery solids Low densities Low melting points
Increase in reactivity as you move from top to bottom
Most reactive is Francium(Fr)

21. What does it mean to be reactive?
We will be describing elements according to their reactivity.
Elements that are reactive bond easily with other elements to make compounds.
Some elements are only found in nature bonded with other elements.
What makes an element reactive?
An incomplete valence electron level.
All atoms (except hydrogen) want to have 8 electrons in their very outermost energy level (This is called the rule of octet.)
Atoms bond until this level is complete. Atoms with few valence electrons lose them during bonding. Atoms with 6, 7, or 8 valence electrons gain electrons during bonding.

22. Alkali Metals Uses: Lithium(Li)—batteries Sodium(Na)—table salt
Sodium(Na) and Potassium(K)—dietary requirements

23. Group 2-Alkaline Earth Metals
Each is denser, harder, and has a higher melting point than the alkali metal in same period
Reactive, but not as reactive as alkali metals

24. Alkaline Earth Metals Uses:
Beryllium(Be)—found in gems emerald and aquamarine
Magnesium(Mg)—found in chlorophyll of green plants

25. Groups 13 thru 18 Not all solid metals
A single group can contain metals, nonmetals, and metalloids
A single group can also have members that are solids, liquids, and gases

26. Group 13—Boron Family
All metals except boron(B) (brittle, black metalloid)
Used to make a variety of products
Cookware—boron(B)
Soft-drink cans—aluminum(Al)
Computer chips--gallium(Ga)

27. Group 14—Carbon Group Carbon(C)—nonmetal
Diamond and graphite
Found in all living things
Silicon(Si) & Germanium(Ge)—metalloid
Semiconductors
Computer chips
Tin(Sn) & Lead(Pb)-metal
Two heaviest elements in group
Lead—x-ray aprons, car batteries
Tin—pewter, toothpaste, coating for steel cans

28. Group 15—The Nitrogen Group
Nitrogen(N) & Phosphorus(P)
Nonmetals
Required by living things
Part of DNA
Nitrogen(N)
80% of air you breathe
Get nitrogen for body from eating plants
Phosphorus(P)
White phosphorus—can’t be exposed to air—it will explode !!
Red phosphorus—used for head of matches
Also needed for healthy teeth and bones

29. Group 16—the Oxygen Family
Oxygen(O)
20% of Earth’s atmosphere
Required for combustion
Ozone shields organisms from radiation
Sulfur(S)
Solid, yellow nonmetal
Used to make sulfuric acid
Paint, fertilizer, detergent, rubber
Selenium(Se)
Conducts electricity when exposed to light
Used in solar cells, photographic materials

30. Group 17—The Halogen Group
All non-metals except for astatine (radioactive metalloid)
Means “salt-former”
Example, table salt—sodium chloride
Most reactive is fluorine
Least reactive is iodine
Chlorine(Cl)kills bacteria in water

31. Group 18—The Noble Gases Rarely combine with other elements
Great for signs
Each glows a different color light when electricity is passed through
Helium(He)
Less dense than air
Great for balloons
Argon(Ar)
Most abundant
Krypton(Kr)
Used to illuminate landing strips
Radon(Rn)
Radioactive; produced naturally
Harmful; can cause lung cancer

32. Transition Elements Groups 3-12 All metals
Most found combined with other elements in ores
Few found as pure elements gold(Au) and silver(Ag)

33. Iron Triad Elements in period 4 Have magnetic properties
Iron, cobalt, nickel
Have magnetic properties
Industrial magnets—alloy of nickel, cobalt, aluminum
Nickel used in batteries
Iron is necessary in hemoglobin to transport oxygen in body
Iron also combined with other metals to produce steel

34. Uses of Transition Elements
Tungsten(W)—highest melting point of any metal
Used as filament in light bulbs
Mercury(Hg)—lowest melting point
Used in thermometers and barometers
Only metal liquid at room temperature
Poisonous to living things

35. Uses of Transition Elements
Chromium(Cr)—comes from Greek word for color, chroma
Used in paints
Platinum(Pt) group
Ruthenium, rhodium, palladium, osmium, iridium, and platinum
Can be used as catalysts
Used to produce electronics

36. Inner Transition Metals
Lanthanide Series
Actinide Series

37. Lanthanides #58-71 Also called rare earth elements
Usually found in combination with oxygen in Earth’s crust
Soft metals that can be cut with a knife

38. Actinides # 90-103 All radioactive
Thorium(Th), protactinium(Pa), uranium(U) are only ones found naturally on Earth
Plutonium(Pu)—used to fuel nuclear power plants
Americium(Am)—used in smoke detectors
Californium-252(Cf)—used to kill cancer cells
Synthetic-Not occur in nature