Ionic Bonding

Ionic Bonds

  • Electrons are transferred from one atom to another creating ions
  • Metal + nonmetal

              ○ Metals form cations (lose e- bcuz low IE) and nonmetals form anions (gain e- bcuz high IE)

              ○ Cations are attracted to anions; (+) & (-) attract

              ○ Nonmetal achieves electron configuration of next noble gas and valence orbitals of metal are emptied

  • Ions are usually more stable than atoms but still unstable because are electrically charged
  • Before losing/gaining electrons, atoms are neutral (no charge)
  • All elements with more than one charge are metals and give away e- (+)

Types of Ions

  • Ions: electrically charged particle

Monatomic = one type of atom (same element)

  • H+, Ca2+, N3-

Polyatomic = many types of atoms (different elements) with a charge; small charged molecules

  • Held by covalent bonds and net charge is not zero

Lewis Dot Structures

  • Valence electrons represented by dots, no more than two per side
  • Can show rearrangement of electrons during chemical reactions
  • Note: → has lost an e- so C will have only 6 ve                                           

Binary Ionic Compounds

  • Contains ions of only two elements Formula: cation first, then anion
    • Charges of atoms written as superscript (on top)

               ○ Number of atoms written as subscripts (on bottom)                               

               ○ Cation has positive charge while anion has negative

  • The total (net) charge on the compound should be zero

Naming Types of Ionic Compounds

  • If cation has more than one valence (can have different charges) indicate the charge using roman numerals in parentheses after the cation name
    • FeO = iron (II) Oxide Binary Ionic Compounds
  • Name cation using its element name
    • Some have common names (ex. Water, sodium)
  • Name anion by dropping ending of the element name and adding -ide

                ○ Ex: Calcium Phosphide → -ide shows that there is one anion 

Polyatomic Ionic Compounds

If anion is polyatomic, name it using the ions name

Will be polyatomic if ends in -ate or -ite

  • -ate = has more oxygen ions
  • -ite = has less oxygen ions

Treat as one whole unit

Always use parenthesis () unless there is only one


     ○ 3 ions

     ○ 5 atoms: two subscript belongs to hydrogen AND oxygen

Covalent Bonding

  • Covalent Bonds: formed by a share of a pair of electrons between two atoms that completes the electron configuration of both atoms

                  ○ Between nonmetals

  • Shared electrons give a lower energy state because they are simultaneously attracted by two nuclei


Types of Covalent Bonds

  • Polar covalent bonds = unequal sharing of e-; charges indicated using small delta

          ○ Due to electronegativity difference: electrons pulled to more electroneg. atom

                  ■ More electroneg. atom becomes slightly (-) (higher e- density)

                  ■ Less electroneg. atom becomes slightly (+)

         ○ Soluble in water (hydrophilic) cuz of charge

  • Nonpolar covalent bonds = atoms of the same element or with similar electronegativity so have equal sharing of e-

        ○ Ex: O₂, N₂, Cl₂

        ○ Even though is bonded to itself, is more stable BUT is a strained bond so is ready to react with a better bond

        ○ No charge

Properties of Covalent Bonds

  ● Low melting points

      ○ Bcuz attraction between e- are easy to overcome

  • Soft, flexible
  • Many won’t dissolve/be disrupted in water (nonpolar)

    ○ Cannot conduct electricity even when dissolved bcuz no charges (+ or -) are present

○ Polar covalent can dissolve cuz of charges

  • Many are liquids at room temperature
  • Flow of electricity:

            ○ NO for nonpolar covalent bonds bcuz e- are tightly held & no charges are present

            ○ YES for polar covalent bonds in molten form bcuz of charges Naming Covalent Bonds

  • Rule 1: Element with lower group number (more left) goes first
  • Rule 2: If elements in same group then greater period number (more down) goes first
  • Rule 3: 2nd element in compound ends in -ide
  • Use greek prefixes to determine number of atoms

           Mono: one         Di: 2            Tri: 3               Tetra: 4         Penta: 5

           Hexa: 6             Hepta: 7       Octo: 8           Nona: 9        Deca: 10

  • If there is only one atom of first element, them NO prefix → just elemental name ○ Ex CO: Carbon monoxide