The Periodic Table

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. LeftRight metalsnon-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 • Thealkali metals, (far left, column 1), arevery reactiveelements 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), arevery reactive gasesthat 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 thehigher 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