Page 4 - Herlihy: The Human Body in Health and Illness, 3rd Edition

c. Carbon always forms covalent bonds; due to the four
electrons in its outer shell
d. Study of carbon-containing substances is called
organic chemistry (inorganic chemistry studies non-
carbon–containing substances).
3. Hydrogen bonds
a. Not due to transfer or sharing of electrons
b. Usually an electrical attraction between molecules
(intermolecular bonds)

C. Ions
1. Definition: atom that carries an electrical charge
2. Types (Table 2-2)
a. Cation: (+) ion, such as Na +
b. Anion: (–) ion, such as Cl –

3. Ionization: ions are formed when an electrolyte dissolves
in water (Figure 2-4)
4. Ion formation
a. A cation is formed when an electron is lost from the
outer shell
b. An anion is formed when an electron is gained in the
outer shell

D. Molecules and Compounds (Figure 2-5)
1. Molecules
a. Formed when two atoms bond