Review – Atoms and Isotopes What is the definition of atom? What is the definition of isotope?
Now, how are these atoms similar? How are they different?
Ion Definition An atom in which the number of electrons does NOT equal the number of protons causing it to have a net positive or negative charge.
Cation Anion 2 Types of Ions Lost electrons Gained electrons Positive charge Negative charge p+ > e- p+ < e-
Why do atoms form ions? Neutral atoms seek stability by gaining and losing valence electrons to satisfy the: Octet rule – Group A elements tend to combine in a way that each atom has 8 valence electrons so that they have electron configurations similar to a noble gas.
Examples Cation (+) Anion (-) Phosphorus # Valence e-? Lewis Dot? Calcium # Valence e-? Lewis Dot? Gain/Lose e-? How many? Ion Notation Phosphorus # Valence e-? Lewis Dot? Gain/Lose e-? How many? Ion Notation 2 5 Ca P Lose Gain 2 3 Ca+2 P-3
Practice 1. Beryllium 2. Fluorine 3. Sulfur 4. Hydrogen 5. Oxygen Element Valence Electrons Lewis Dot Gain/Lose e-? How many? Ion Notation 1. Beryllium 2. Fluorine 3. Sulfur 4. Hydrogen 5. Oxygen 6. Gallium 7. Nitrogen 8. Cesium 9. Aluminum 10. Iodine Be+2 F-1 S-2 H+1 O-2 Ga+3 N-3 Cs+1 Al+3 I-1
Naming Ions Positive ions keep their name Ex. Sodium ion (Na+) Negative ions end with suffix –ide Ex. Chloride ion (Cl-)