1. The Periodic Table

2. Why Do We Use Tables? We use tables to organize data (information)
Table help us see relationships, patterns, and similarities.

3. What is the Periodic Table?
The periodic table is a table listing all the elements in an organized form.
The periodic table is organized by the similar characteristics of the elements.
Elements are listed in order of increasing atomic number.

4. What is an Element?
An element is the simplest form of a substance that retains the properties and characteristics of that substance.
Examples: Carbon, C; Hydrogen, H, Nitrogen, N; Oxygen, O.

5. Chemical Nomenclature
In the scientific community, elements are listed and referred to by using symbols.
First letter of name:
Hydrogen = H
First and second letter of name:
Helium = He
First and third letter of name
Chlorine = Cl
Exceptions = Latin names:
Gold = Au (for Auric), Iron = Fe (for Ferric)

6. The First Table
Dmitri Mendeleev formed the first table organizing the elements by their atomic mass.
He also noticed other similarities among elements:
Density
Reactivity
Maleability

7. Periodic Patterns
Mendeleev noticed that these characteristics repeated in a pattern.
Repeating patterns are called periodic so he named his table the Periodic Table of the Elements.

8. Mendeleev’s Table

9. How is the Modern Periodic Table Organized?
The elements are organized by increasing atomic number and similar characteristics.
Elements are similar to other elements found in the same row or column.

11. Periods, “Rows”
The properties of elements in the same period, (row across), gradually change as you move from left to right.
Left Right
metals non-metals

12. Groups, “Families”
Groups, or “families”, are columns that go up and down in the table.
Elements in the same group, or family, have the same number of electrons in their outer shell.
Elements in the same group will combine with other elements in the same way.

13. Groups with Family Names
Some groups of the periodic table have “family names” that indicate their similar characteristics.
Alkali Metals
Alkaline Earth Metals
Coinage Metals
Halogens
Inert “Noble” Gases

14. Alkali Metal Family
The alkali metals, (far left, column 1), are very reactive elements because they have only one electron in their outer energy level.
Easy to loose one electron so very reactive.
Alkali metals will immediately react with air, water, and other substances in the environment.
Characteristics: soft (cut w/a knife, have luster, and conduct heat and electricity.

16. Alkaline Earth Metal Family
Alkaline earth metals, (column 2), are reactive, (but not as reactive as alkali metals), because they have 2 electrons in their outer energy level.
Fairly easy to loose 2 electrons so fairly reactive.
Characteristics: soft (but harder than alkali metals), have luster, conduct heat and electricity.

17. Alkaline Earth Metals

18. Coinage Metal Family
Contain the metals used to make coins. These metals have various numbers of valence electrons which allows the metals to combine with other metals to form coins.
Copper, Cu; Silver, Ag; Gold, Au;

19. Halogen Family
Halogens, (group 17, 2nd from right), are very reactive gases that contain 7 electrons in the outer energy level.
Easy to gain one electron so very reactive.

21. Inert, “Noble”, Gases Family
The inert gases (group 18, far right) have full outer energy levels (8 electrons) so they are non-reactive, or “inert”.

23. Inert Gases
Neon
Argon

24. What is Reactivity?
Reactivity is how easily an element will combine with other elements.
High reactivity = easier to combine
Elements combine with other elements by gaining, loosing or sharing electrons.

25. Reactivity of Metals
Metals will loose electrons when they combine with other elements.
The farther away electrons are from the nucleus the easier they break away so the bigger metals have higher reactivity.

26. Reactive Metals

27. Reactivity of Non-Metals
Non-metals will gain electrons when combining with other elements.
The closer electrons are to the nucleus the stronger the force of attraction so the smaller the non-metal the higher the reactivity.

28. Reactive Non-metals

29. Energy Levels of Elements
Energy levels indicate the distance from the nucleus where the electrons are found.
Different energy levels can contain different amounts of electrons.
K (the first level) can contain 2 electrons
L (the 2nd level) can contain 8 electrons
M (the 3rd level) can contain 18 electrons
N (the 4th level) can contain 32 electrons

30. Energy of Electrons
The closer an electron is to the nucleus, the more energy it takes to separate it from the nucleus.
The farther away an electron is from the nucleus, the more energy the electron has.

31. Diagram of Energy Levels

33. What are Valence Electrons?
Valence electrons are the electrons that are found in an elements outer-most energy level.
Valence electrons are those involved in chemical bonding of elements.

34. Dot Diagrams
A dot diagram is a simple way to show valence electrons and how an element will combine.
Dot diagrams only show the element and the valence electrons (those electrons that are available for bonding)

35. Examples of Dot Diagrams

36. Why Do Elements Combine?
Elements will combine with other elements to become more stable.
Combining allows elements to fill their outer energy levels.

38. What is an Ion? An ion is a charged atom.
An atom that has gained or lost electrons is no longer neutral and now has either a positive “+” or negative “-” electrical charge.

39. What is an Isotope?
An isotope is an atom of an element that has the same number of protons, atomic number, as another atom but a different number of neutrons.

40. Elements, Mixtures, and Compounds
Element = the simplest form of a substance that retains the properties of that substance.
Mixture = when 2 or more elements are combined in a manner that the properties of each element do not change. In a mixture the original elements can be separated by physical means.
Compound = a substance formed by the combination of elements in fixed proportions and involving a chemical reaction. In a compound the original elements can not be separated by physical means.

41. Example of How Elements of the Same Group Will Combine in the Same Way

42. What is a Chemical Formula?
Chemical formulas, or molecular formulas, are a shorthand representation of the elements of a substance.
Chemical formulas tell the exact makeup of a substance.
Ex. H2O = 2 atoms of Hydrogen and 1 atom of Oxygen.
C6H12O6 = 6 Carbon, 12 Hydrogen, and 6 Oxygen atoms