CHEMISTRY PART 4 Reactivity and Ions
Reactivity Atoms want to be stable. Want a full valence shell. Want to be like the nearest Nobel Gas The Nobel Gases are very stable. Unreactive.
Think about it... Which group of elements would be the most reactive? Metals alkali (1 valence e-) Non-metals halogens (7 valence e-)
Reactivity Example Sodium Na 11 electrons Group 1 1 valence e- How can Sodium be like the nearest Nobel Gas? Add 7 to be like Ar Lose 1 to be like He
Reactivity Example Sodium will lose its 1 valence e-. This is easier. The shell will no longer exist. Na will now have 10e- on two shells like Ne Na now has 11p+ and 10e- It now has a +1 charge.
Reactivity Example How can S become stable? Group 16 6 valence e- Gain 2e- S now has 16p+ and 18e- It now has a -2 charge.
Ions An atom or group of atoms that carries an electric charge.
Ions Cation A positively (+) charged ion. Formed by losing electrons. Almost all metals are cations. Groups 1 and 2.
Ions Anion A negatively (-) charged ion. Formed by gaining electrons. Mostly group 7 (halogens) and group 6.
Naming Ions Cation Metals Name is the full atom name. Sodium ion Na +
Naming Ions Anion Non-Metals Name of atom ends in “ide”. Chloride ion Cl - Oxide ion O 2-
Practice Worksheet Page 109 # 4, 9