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Ions

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Atoms versus ions

The same atom can have radically different behaviors, depending on the number of electrons it has.

Your body requires Na (sodium), but pure sodium atoms are literally explosive on contact with water.  Yet the Na in your food doesn’t explode – so something must be going on.

Atoms – by themselves – would normally be neutral:

they have the same number of electrons (negative) and protons (positive)

Yet atoms can gain or lose electrons

When this happens they are no longer neutral – they are now charged.

Charged atoms are called ions.

Ions have completely different behaviors than neutral atoms.

Na (neutral atom) = highly explosive

Na + (positive charged ion) = essential for all cell activity.
You’d die in an instant without some being in every cell in your body.

Cl (neutral atom) = always forms Cl2 molecules, poison gas.

Cl-  (positive charged ion) = essential for all cell activity.
You’d die in an instant without some being in every cell in your body.

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Abbreviations:   p = protons, e = electronsm n = neutrons

The atomic number of an element is also called a proton number

This tells you the # of protons in an atom.

A normal atom has a neutral charge:

    Equal numbers of + and – particles.

    # e = # p

Ions are atoms with extra electrons, or missing electrons.

When atom is missing e, then it has a + charge

When atom has extra a, then it has a – charge

Ions have completely different behaviors than neutral atoms.

Consider Na (a neutral sodium atom) = highly explosive

But Na easily loses e.  So we formally find it as a + charged ion.

Na + = non-explosive, and in every cell in our bodies. Essential for cell activity. You’d die in an instant without this.

Sodium ion

Cl (neutral, atom) = always forms Cl2 molecules. Deadly poison gas.

Cl-  = non-poison, and in every cell in our body.

Essential for cell activity. You’d die in an instant without this.

Example: Calcium atoms usually lose 2 e, as shown here.

Calcium Atom and Ion

When 2 neutral atoms get close, one can pull off the other’s electron

Na and Cl atoms forming ions Sodium Chlorine

Chlorine: terminology

People sometimes use the same word to describe different things. For example, “chlorine” can refer to:

A. Chlorine atom – a single, neutral, chlorine atom. These are unstable. We normally never encounter one. They bind to each other to form chlorine molecules.

B. Chlorine molecule (Cl2) – deadly gas

C. Chlorine ion – A chlorine atom that picked up an electron. In small quantities these are essential for life.

D. Chlorine bleach aka sodium hypochlorite (NaOCl)
This is a disinfectant used to kill bacteria in swimming pools. What is the chemical structure of sodium hypochlorite ?

We can visualize the electron distribution in sodium hypochlorite a little more accurately

https://en.wikipedia.org/wiki/File:Sodium-hypochlorite.png
https://en.wikipedia.org/wiki/File:Sodium-hypochlorite.png

How to make sodium hypochlorite?

Add chlorine gas (Cl2) to caustic soda (NaOH).

Cl2 + 2NaOH + → NaOCl + NaCl + H2O

How does sodium hypochlorite disinfection work? By adding hypochlorite to water, hypochlorous acid (HOCl) is formed.

NaOCl + H2O → HOCl + NaOH

This hypochlorous acid is then broken down into hydrochloric acid (HCl) and oxygen (O). This acid will kill most bacteria, viruses and fungi.

 

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