periodic_trends_2.ppt

periodic_trends_2.ppt

• 1.
  The Periodic Table trends
• 2.
  History of thePeriodic Table • 1871 – Mendeleev arranged the elements according to: 1. Increasing atomic mass 2. Elements w/ similar properties were put in the same row. • 1913 – Moseley arranged the elements according to: 1. Increasing atomic number 2. Elements w/ similar properties were put in the same column.
• 5.
  Increasing energy 1s 2s 3s 4s 5s 6s 7s 2p 3p 4p 5p 6p 3d 4d 5d 7p 6d 4f 5f Review ofElectron Configuration
• 6.
  Periodic Table &Electron Configuration Behold! The Pattern to the Periodic Chart
• 7.
  Periodic Groups • Elementsin the same column have similar chemical and physical properties. • These similarities are observed because elements in a column have similar e- configurations (same amount of electrons in outermost shell).
• 8.
  Know the GroupNames
• 9.
  Periodic Trends • Trendswe’ll be looking at: 1. Atomic Radius and Ionic Radius 2. Ionization Energy 3. Electronegativity 4. Reactivity 5. Metallic Character
• 10.
  Atomic Radius • AtomicRadius – size of an atom (distance from nucleus to outermost e-).
• 11.
  Atomic Radius Trend •Group Trend – As you go down a column, atomic radius increases. As you go down, e- are filled into orbitals (energy levels) that are farther away from the nucleus (attraction not as strong). • Periodic Trend – As you go across a period (L to R), atomic radius decreases. As you go L to R, e- are put into the same energy level, but more p+ and e- total (more attraction = smaller size).
• 12.
  Ionic Radius • IonicRadius - size of an atom when it is an ion.
• 13.
  Ionic Radius Trend •Metals – lose e-, which means more p+ than e- (more attraction) SO… Ionic Radius < Neutral Atomic Radius • Nonmetals – gain e-, which means more e- than p+ (not as much attraction) SO… Ionic Radius > Neutral Atomic Radius
• 14.
  Ionic Radius Trend •Group Trend – As you go down a column, atomic radius increases. • Periodic Trend – As you go across a period (L to R), atomic radius decreases.
• 15.
  Ionization Energy • Ionization Energy– energy needed to remove outermost e-.
• 16.
  Ionization Energy • GroupTrend – As you go down a column, ionization energy decreases. As you go down, atomic size is increasing (less attraction), so easier to remove an e-. • Periodic Trend – As you go across a period (L to R), ionization energy increases. As you go L to R, atomic size is decreasing (more attraction), so more difficult to remove an e- (also, metals want to lose e-, but nonmetals do not).
• 17.
  How do electronconfigurations explain why there is a big change in energy at the red line? Energy to Take Off Several Electrons
• 18.
  Electronegativity • Electronegativity- tendency ofan atom to attract e-.
• 19.
  Electronegativity Trend (really electronaffinity) • Group Trend – As you go down a column, electron affinity decreases. As you go down, atomic size is increasing, so less attraction of electrons to the nucleus. Periodic Trend – As you go across a period (L to R), electron affinity increases. As you go L to R, atomic size is decreasing, so the electrons are more attracted to the nucleus.
• 20.
  Reactivity • Reactivity –tendency of an atom to react. • Metals – lose e- when they react, so metals’ reactivity is based on lowest Ionization Energy (bottom/left corner) – Low I.E = High Reactivity. • Nonmetals – gain e- when they react, so nonmetals’ reactivity is based on high electronegativity (upper/right corner). – High electronegativity = High reactivity
• 21.
  Metallic Character • Propertiesof a Metal – – Easy to shape (malleable); many are ductile (can be pulled into wires) – Conduct electricity and heat – Shiny • Group Trend – As you go down a column, metallic character increases (because ionization energy decreases). • Periodic Trend – As you go across a period (L to R), metallic character decreases (because ionization energy decreases) (L to R, you are going from metals to non- metals).
• 22.
  Do This… • Basedon these trends, can you describe some properties of the following groups? • Alkali • Alkaline • Halogens • Noble Gases – Also, be able to identify metals, transition metals semi- metals, and non-metals and know some properties of each.