covalent bonds and structures

• what is a covalent bond?

  a chemical bond formed by sharing a pair of electrons
• why do atoms form covalent bonds to form diatomic molecules?

  they have incomplete outer shells so are unstable and chemically reactive. They share electrons so each atom gains a full outer shell.
• why can't covalent bonds form between atoms in noble gases?

  they already have full outer shells and are chemically inert
• covalent bonds form between which substances?

  two non-metals
• What are two differences between ionic and covalent bonds?

  -ionic bonds occur between ions, covalent bonds occur between atoms

  -ionic bonds involve transferring electrons, covalent bonds involve sharing electrons
• Describe the structure of a macromolecule?

  a giant covalent lattice
• What is the difference between a molecule and a macromolecule?

  molecules have a fixed number of atoms, but macromolecules have an indefinite size (and can always be made larger)