Chemistry Electron Energy Levels and Bonding

Electron Energy Levels

• Electron energy decreases when closer to the nucleus.

Electron Configuration of Calcium

• This information is not provided in the text.

Electron Orbital Diagram of Nitrogen

• This information is not provided in the text.

Valence Electrons

• Valence electrons are the outermost electrons involved in bonding.
• Energy levels and the maximum number of electrons they can hold are:
  • 1st Energy Level: 2 electrons
  • 2nd Energy Level: 8 electrons
  • 3rd Energy Level: 18 electrons
  • 4th Energy Level: 32 electrons

Types of Chemical Bonding

• Ionic Bonding: Transfer of electrons between nonmetals and metals.
• Covalent Bonding: Sharing of electrons between nonmetals.
• Metallic Bonding: Sea of electrons between metals.

Element Groups in the Periodic Table

• Element groups are listed in the periodic table.
• Group number, configuration, and number of valence electrons are shown in a table.
• Example: Group 1 elements (Na, Li) have 1 valence electron (s¹).

Chemical Bonding & Atoms

• Electrons jumping between energy levels produces colored light.
• Atoms bond to become stable or attain electronic configuration of a noble gas.
• Atoms bond to form compounds.
• Ionic bonds form when the electronegativity difference is greater than 1.9. Examples include NaCl, NaF, and KCl
• Anions gain electrons and become negatively charged.
• Cations lose electrons and become positively charged.

Group 1A (+1) Examples

• Sodium (Na)
• Lithium (Li)

Group 3 (+3) Examples

• Aluminum

Ionic Charges in Periodic Table

• Group 1A or Group I elements form +1 ions
• Group 3 elements form +3 ions

Covalent Bonding Examples

• Methane (CH4)
• Diamond (Carbon)

Properties of Ionic Compounds

• Form crystals
• Conduct electricity in aqueous solutions
• Hard and brittle

Properties of Covalent Molecular Compounds

• Soft and flexible
• Flammable
• Low melting and boiling points

Properties of Metals

• Malleable (can be shaped)
• Ductile (can be drawn into wires)

Conductivity & Malleability of Metals

• Metals are good electrical conductors due to a "sea" of free electrons within the lattice structure of metal ions.

Uses of Carbon Compounds

• Hydrocarbons are used as fuels (e.g., methane, butane).
• Other examples include: Isopropyl Alcohol, Ethyl Alcohol, Formalin, Acetone, Ethyne, Kerosene, Gasoline.

Alkanes

• Hydrocarbons with single bonds
• Examples: methane, ethane, propane, butane, pentane, octane.
• Octane has a higher boiling point than the other examples given