Polyatomic Ions, Valence Electrons, and Explosions!

Today we started class by recapping that the families on the periodic table have similar properties.

Specifically we talked about the Alkali metals and how the Alkali metals reactivity intensives as you go down. For example if you go down the list : Li, Na, K, Rb, Cs, Fr. Their corrosive reactivity speed with oxygen increases along with their explosiveness with water. So lithium slowly corrodes away in the presence of oxygen, while Francium corrodes away practically instantly. Although the credibility of the actually explosives in the video below are questionable it definitely helps to illustrate the point. :)



Soon after we began talking about valence electrons. The number of valence electrons an element has correspond to the group number they are in.
For Example:

• Group 1 -> 1 Valence Electron
• Group 2 -> 2 Valence Electrons
• Groups 3-12 do not follow this rule and should be ignored (for now)
• Group 13 -> 3 Valence Electrons
• Group 14 -> 4 Valence Electrons
• etc...

Common Polyatomic Ions
Here is a list of some of the common polyatomic ions that we went over in class.

• OH^- Hydroxide
• NH₄⁺ Ammonium
• NO₃^- Nitrate
• CO₃^2- Carbonate
• PO₄^3- Phosphate
• SO₄^2- Sulfate

We finished the discussion by talking about how many electrons elements want to loose to become stable. Basically elements in Groups 1-2 and 13-14 what to have a full outer set of electrons or have 8 electrons in their outer level. To accomplish this elements can do a range of things that don't always follow an exact model. General speaking though elements will do whatever is easiest.
For Example:

• Elements in Group 2 typically loose 2 electrons.
• Elements in Column 1 typically loose 1 electron.
• Elements in Group 16 typically like to gain 2 electrons.

Using the general guidelines above a pattern begins to arise.

1. Metals generally form positive ions.
2. Nonmetals generally form negative ions.

That was are day in a nutshell. I intentionally didn't go over the notes because I think the speak incredibly well for themselves. If you misplaced yours our simply want to test your knowledge you can flip through the slides below.

Periodic table

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