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Chapter 2

Chapter 2. Elements are the Building Blocks of Matter. Pure Substance . A material that is made up of particles that are identical to each other. (all the same) Have their own set of properties - boiling point, density … Two types of Pure Substances

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Chapter 2

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  1. Chapter 2 Elements are the Building Blocks of Matter

  2. Pure Substance • A material that is made up of particles that are identical to each other. (all the same) • Have their own set of properties - boiling point, density … • Two types of Pure Substances - Elements(Gold, Hydrogen) - Compounds(Pure Water, Salt)

  3. Elements • pure substance with 1type of atom • cannot be broken down or separated into simpler substances. • 109 different types of elements • Are arranged in a Periodic Table according to their Atomic Number (# of protons in their Nucleus)

  4. Elements and Chemical Symbols • In chemistry each Element has its own symbol which is used to show chemical formulas. [ NaCl ] • Different ways to name Elements with symbols : • First Letter - Carbon - C • First (2) Letters - Cobalt – Co • First and Third - Chromium – Cr • Latin or Non English - Iron – Fe [ Ferrum ] • Use same symbols around the world to communicate with different countries. (common language)

  5. Twenty Common elements

  6. Symbols and Jokes

  7. Element Jokes and Puns Question : Anyone know any jokes about sodium? Answer: Na

  8. Please accept my apology ! • Sorry for making bad chemistry jokes but all the good ones Argon !!!!!!

  9. Let’s Get Serious… one more

  10. Question to consider… • What is the difference between Co and CO? (hint look at the periodic table for help)

  11. Atomic Number and Mass Number • Each Element has (2) numbers written in the periodic table. • Atomic Number - smaller number that tells you the number of Protons and Electrons in an atom • Mass Number -bigger number that tells you how heavy the atom is (amu) • Mass # = proton # + neutron #

  12. Copy into notebook (example) # Protons (Electrons) # Protons + Neutrons

  13. Element - Atomic # and Mass #

  14. Element – Atomic # and Mass#

  15. Examples

  16. New Element Discovered !!!!

  17. Time for one more PUN ….. • Silver walks up to Gold in a party and says, "Au, get outta here!“ • We would like to apologize for not adding more element jokes... but we only update them.... Periodically !!!

  18. The First Periodic Table • First designed by Dmitri Mendeleev (1869) • First table consisted of only 63 elements. • He left spaces for future elements that would be later discovered • The table was later finished by later scientists.

  19. Mendeleev’s Periodic Table There are a lot of gaps, but look at the horizontal rows (periods) and compare to the current periodic table.

  20. Current Periodic Table

  21. Periodic Table (General Characteristics) • Periodic table: a chart that organizes all known elements according to their physical and chemical properties • Arranged according to Atomic Number • (Number of protons ) increases from (Left ---Right) • Made up of (2) Major Groups: Metals and Non-Metals • Has (7) Rows - (Periods) • Has (18) Columns – (Groups) or (Families)

  22. Periodic Table • Table is made up (2) major groups (Metal and Non metals) separated by a Ladder Shaped Line

  23. Periodic Table • Remember that there are (3) Groups of elements in the Periodic Table : 1)Metals , 2)Non- Metals and 3) Metalloids or Semi –Metals.

  24. Elements are grouped on the basis of similar characteristics (3) major groups of Elements are: Metals, non-metals and Metalloids (semi- metals) Ductile: ability of a substance to be pulled or stretched. Malleable: ability of a substance to be bent or molded into different shapes.

  25. Color our Periodic Table • Metals – BlueNon- Metal– Red • Metalloids (Semi-Metals)- circle them

  26. Some other Special Groups within the Periodic Table • Transition Metals- (tough metals) - center of Periodic Table • (4)Special Groups or Families (columns) • Alkali Metals (Group 1)… ( 1) • Alkaline Earth Metals (Group 2) …. (2) • Halogens(Group 17) …. or (Vii) • Noble Gases (Group 18)…. (Viii) or (0)

  27. Special Groups of Elements

  28. Alkali Metals – Family 1 (Group 1) • Alkali Metals (Column 1) • Very reactive and soft • React with water, oxygen and other non-metals • Low melting points • Reactivity increases as you move down the column

  29. Alkaline Earth Metals – Family 2 (Group 2) • Alkaline Earth Metals (column 2) • Less reactive than Alkali Metals • Burn in air if heated, produce bright flames and used in fireworks • Also reacts with water • Reactivity increases as you move down the column

  30. Halogens- Family 17 (Group 17) (Group vii) • Halogens (Column 17) • Non-metals and highly reactive • Fluorine and Chlorine are gases, Bromine is a liquid and Iodine is a solid • Reactivity decreases as you move down the column • Astatine is very rare and little is known about it

  31. Noble Gases- Family 18 (Group 18) (Group Viii or 0) • Noble gases (column 18) • Most stable and unreactive elements • At room temperature they are colorless and odorless • Some gases, like Argon and Neon are used in light fixtures • Helium is lighter than air and is used in balloons.

  32. Noble Gas Joke • Helium walks into a restaurant , • The waitress says "We don't serve noble gasses in here." • Helium doesn't react.

  33. Another Chemistry Joke • Two chemists go into a restaurant. • The first one says "I think I'll have an H2O." • The second one says "I think I'll have an H2O too" – and he died.

  34. Locating Elements on the Periodic Table • Make sure you can identify the relative position of elements on the periodic table • What element is located at period 2, family 3? • Boron

  35. Bohr – Rutherford Diagrams • Need to review the Atom • Protons • Electrons • Neutrons • Energy Levels 2,8,8,18

  36. Atomic Structure • Bohr-Rutherford Diagram: • shows how many electrons are in each energy level (electron shell) surrounding the nucleus. • Energy Level (or electron shell): • the space around the nucleus in which the electrons may be found. • Known as the 2-8-8-18pattern • The shell closest to center can hold 2 electrons • The 2nd shell can hold up to 8 electrons • The 3rd shell can hold up to 8 electrons • The 4thshell can hold up to 18 electrons.

  37. How to Draw Bohr-Rutherford Models • Step 1: Draw Nucleus • Step 2: Put symbol, number of protons and number of neutrons in the Nucleus • Step 3: Use the 2-8-8-18 pattern to fill the energy levels.

  38. Bohr – Rutherford Diagram Example • Diagram that includes (2) parts – • inside the nucleus (number of protons and neutrons) • energy levels around the nucleus (electrons) • Example (Sodium) Bohr- Rutherford Diagram and electrons

  39. How to Draw Bohr-Rutherford Models • Step 1: Draw Nucleus • Step 2: Put symbol, number of protons and number of neutrons in the Nucleus • Step 3: Use the 2-8-8-18 pattern to fill the energy levels. • NOTE: the first energy level is filled first completely before going to the second, the second is filled before going to the third and so on. • Draw Bohr – Rutherford Diagram for Magnesium • See page 62, figure 2.24

  40. Bohr-Rutherford… • Valence Energy Level: • the energy level that is the furthest from the nucleus • Valence Electrons: • Electrons that are furthest away from the nucleus. • They occupy the valence energy level

  41. Patterns Observed Using Energy Level Diagrams • Elements in the same family have the same number of electrons in their valence energy level • Period number indicates the number of energy levels • The valence energy level structure determines how one element will react with another. Group 1 and Group 17 (Vii) • If the valence level is full, then it is difficult to react (look at Noble gases) • Website to show the similar properties of elements in families • http://videos.howstuffworks.com/hsw/5793-periodic-table-families-video.htm

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