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.