Ions Valency Table 3.6 Quiz

Study Notes

Common ions include sodium (Na+), potassium (K+), silver (Ag+), copper (Cu+), magnesium (Mg2+), calcium (Ca2+), zinc (Zn2+), iron (Fe2+/Fe3+), and aluminum (Al3+).
Nonmetallic ions include hydride (H-), chloride (Cl-), bromide (Br-), and iodide (I-).
Polyatomic ions consist of ammonium (NH4+), hydroxide (OH-), nitrate (NO3-), and hydrogen carbonate (HCO3-).
Some elements, such as copper and iron, exhibit more than one valency, indicated by Roman numerals (e.g., copper (I) as Cu+ and copper (II) as Cu2+).

The charges on ions must be balanced when forming compounds.
Write the metal name or symbol first followed by the non-metal. Examples include:
- Calcium oxide (CaO)
- Sodium chloride (NaCl)
- Iron sulfide (FeS)
For polyatomic ions, enclose the ion's formula in brackets and indicate the quantity outside the brackets, e.g., Mg(OH)2 for magnesium hydroxide.

Atomicity refers to the number of atoms in a molecule of an element.
Common compounds and their mass ratios include:
- Water (H2O): 1 part hydrogen to 8 parts oxygen (1:8)
- Ammonia (NH3): 14 parts nitrogen to 3 parts hydrogen (14:3)
- Carbon dioxide (CO2): 3 parts carbon to 8 parts oxygen (3:8)

The ratio by number of atoms for water is H:O = 2:1, derived from the atomic masses of hydrogen and oxygen.

Ions are charged species formed from atoms or groups of atoms.
Ions can be either negatively charged (anions) or positively charged (cations).
Example: In sodium chloride (NaCl), sodium is a cation and chlorine is an anion.