In-depth Chemistry Notes on Elements and Bonding

Metals

• Definition: Metals are elements that possess several key properties:

  • Shiny
  • Malleable
  • Can be hammered into thin sheets.
  • Ductile
  • Can be drawn into wires.
  • Solid state at room temperature (except mercury).
  • Good conductors of heat and electricity.

• Bonding in Metals:

  • Atoms usually have one to three electrons in their outermost energy levels.
  • Tend to lose electrons easily, resulting in positive ions.
  • Bond with non-metals through ionic bonding where
  • Metal Atoms: Lose electrons and become positive ions.
  • Non-metal Atoms: Gain those electrons and become negative ions.

• Metallic Bonding:

  • Electrons move freely among positively charged metal ions.
  • This explains characteristics such as ductility and electrical conductivity.

• Alkali Metals (Group 1):

  • Soft and highly reactive.
  • Not found naturally; stored in oil.

• Alkaline Earth Metals (Group 2):

  • Contains 2 outer electrons, reactive, and not found free in nature.

• Transition Metals (Groups 3-12):

  • Form colored compounds and found uncombined in nature.
  • Includes the iron triad: Iron, Cobalt, and Nickel (common magnetic elements).
  • Coinage metals: Copper, Silver, Gold (stable, malleable).

• Inner Transition Elements:

  • Two disconnected rows:
  • Lanthanides: Follow Lanthanum.
  • Actinides: Follow Actinium.
  • Both rows are radioactive and unstable.

Non-Metals

• Definition: Most of the human body's mass consists of non-metals such as Oxygen, Carbon, Nitrogen, etc.

  • Generally gases or solids at room temperature; brittle or powdery when solid.
  • Poor conductors of heat and electricity, with electrons not free to move.

• Position in the Periodic Table:

  • Non-metals, except hydrogen, are located to the right of the staircase line.
  • Group 18 consists only of non-metals (noble gases).

• Bonding in Non-Metals:

  • Non-metals become negative ions in ionic bonding (e.g., Calcium Fluoride).

• Covalent Bonding:

  • Involves sharing of electrons.
  • E.g., Hydrogen (H) and Helium (He) share electrons for stability.

• Hydrogen:

  • Most abundant element in the universe, often found in water (H2O).
  • Exists as diatomic molecules (H2) when not combined.

• Halogens (Group 17):

  • Elements include Fluorine, Chlorine, Bromine, Iodine, and Astatine.
  • Highly reactive; need one more electron to complete their outer energy levels, forming salts with metals.

• Properties of Halogens:

  • Fluorine: Most chemically active; used in toothpaste.
  • Chlorine: Disinfects water and is the most abundant halogen.
  • Bromine: Only non-metal liquid at room temperature; stains DNA samples.
  • Iodine: Essential in diets, forms purple vapor when heated.
  • Astatine: Rare and radioactive, potential cancer treatment investigational.

• Noble Gases (Group 18):

  • Stable due to full outer shell; exist as isolated atoms.
  • Use in signs and lasers; e.g., Helium in balloons.

Mixed Groups

• Metalloids:

  • Elements with properties of both metals and non-metals.
  • Located along the staircase line (Groups 13-17).

• Boron Group (Group 13):

  • Includes Boron, Aluminum (most abundant metal in Earth's crust), etc.

• Carbon Group (Group 14):

  • All have 4 outer electrons.
  • Carbon: Found in coal and organic compounds.
  • Silicon: Second abundant, used in semiconductors.
  • Tin: Prevents corrosion, used in bronze and pewter.

• Nitrogen Group (Group 15):

  • Elements with 5 electrons in the outer shell.
  • Nitrogen is essential for fertilizers; Phosphorus is used in various industries.

• Oxygen Group (Group 16):

  • Six outer electrons.
  • Oxygen forms diatomic molecules; Sulfur has various allotropes.

Discovering and Making Elements

• Historical Context:

  • Initially, only naturally occurring elements were known.
  • Synthetic elements are made through heavy ion acceleration to study atomic forces.

• Transuranium Elements:

  • Elements with more than 92 protons, all synthetic and generally unstable, mainly found at the bottom of the periodic table.