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