U3 Mendeleev Periodic Table Basics

Honors Chemistry Unit 3, Day 1: Mendeleev and Organization of the Periodic Table

Warm-up Activities

• Students were asked to write down at least 6 facts they already know about the periodic table.

Assignments and Deadlines

• Flame test labs: Due on Schoology by Monday, September 15^{th} at 10:00 pm.

• IN U3 page 3-4: To be completed.

• INSPIRE Unit 3: Due on Monday, September 22^{nd} at 10:00 pm.

History of the Periodic Table

• Dmitri Mendeleev (Russian, 1869)

  • Organized elements by increasing atomic mass.

  • Grouped elements with similar properties together.

  • Experienced some discrepancies in his arrangement.

  • Predicted properties of undiscovered elements: His predictions were remarkably accurate, as later experimental results confirmed.

    • Eka-aluminum (1871) predictions compared to Gallium (1875) experimental results:

      • Atomic weight: Predicted 68, Experimental 69.9

      • Specific gravity: Predicted 6.0, Experimental 5.935 (4.7)

      • Atomic volume: Predicted 11.5, Experimental 11.7

    • Eka-boron (1871) predictions compared to Scandium (1879) experimental results:

      • Atomic weight: Predicted 44, Experimental 43.79

    • Eka-silicon (1871) predictions compared to Germanium (1886) experimental results:

      • Atomic weight: Predicted 72, Experimental 72.3

      • Specific gravity: Predicted 5.5, Experimental 5.47

      • Atomic volume: Predicted 13

• Henry Moseley (1913)

  • Organized elements by increasing atomic number (number of protons).

  • Resolved the discrepancies present in Mendeleev's atomic mass arrangement.

• Glenn Seaborg

  • Contributed by moving the Lanthanides and Actinides block to the bottom of the periodic table structure.

  • Later had an element (Seaborgium, Sg) named after him.

• Other Significant Contributors to the Classification of Elements

  • John Newlands (1837-1898)

    • Arranged elements by increasing atomic mass.

    • Noticed a repetition of properties every eighth element, which led to the law of octaves.

  • Lothar Meyer (1830-1895)

    • Demonstrated a connection between atomic mass and elements' properties.

    • Arranged elements in order of increasing atomic mass.

  • Henry Moseley (1887-1915)

    • Discovered that atoms contain a unique number of protons, known as the atomic number.

    • Arranged elements by increasing atomic number, which established a periodic pattern of properties.

Periodic Table Basics: Information on Each Element Box

• Chemical Name

• Atomic Number (representing the number of protons)

• Chemical Symbol

• Average Atomic Mass in Atomic Mass Units (AMU)

Characteristics and Organization of the Periodic Table Parts

• Metals

  • Typically shiny.

  • Tend to donate electrons to become positively charged ions.

  • Malleable (can be hammered into thin sheets).

  • Ductile (can be drawn into wires).

  • Good conductors of electricity.

• Transition Metals

  • A specific type of metal.

  • Can exhibit various numbers of electrons they lose (variable oxidation states).

• Non-metals

  • Usually not shiny; several are gases at room temperature.

  • Tend to accept electrons to become negatively charged ions.

  • Brittle (break easily).

  • Do not conduct electricity (act as insulators).

• Metalloids

  • Possess some characteristics of metals and some of non-metals.

• Lanthanides and Actinides

  • Mostly synthetic (man-made).

  • Most are radioactive.

• Periods

  • Go across the periodic table horizontally.

  • Elements within the same period do not necessarily share related characteristics.