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Sailboat Owner's Guide to Corrosion - Basic Theories (Collier 1-4)

Oct 19, 2017
6,850
O'Day 19 Littleton, NH
So, Collier stated that an element's most stable state is when it has neutral charge. All elections fill its valence with no extra.
A bonded molecule may be covalenty bonded or chemically bonded. A chemical bond differs from covalent bonding in that two atoms joined by a covalent bond share electrons in their valence. Both atoms need to be positively charged (missing electrons) and two atoms joined by chemical bond means one atom needs to be negatively charged while the other is positively (one atom is missing electrons while the other has too many electrons). Chemically bonded atoms don't share valence electrons.

Does this make for a weaker bond?

How does an atom get to be negatively charged without adding another electron shell?

To add to our list of definitions, Collier says Ions are charged atoms or molecules, either negatively or positively.

It is these ions that we are really concerned with regarding corrosion.

-Will (Dragonfly)
 
May 17, 2004
3,374
Beneteau Oceanis 37 LE Havre de Grace
I’m still on vacation, so I don’t have my book yet, but I’m learning tremendously from this thread in the meantime.

I’ll try to help out a little with what I remember from high school and college chemistry.
Both atoms need to be positively charged (missing electrons) and two atoms joined by chemical bond means one atom needs to be negatively charged while the other is positively (one atom is missing electrons while the other has too many electrons).
I wouldn’t really say the atoms come into the relationship as positively or negatively charged. They have partially filled valence shells, which means they aren’t in their lowest possible energy state. They want to have full valence shells to lower their energy. They are still neutrally charged because they have equal protons and electrons. When they are combined and enough activation energy added, they will share their valence electrons with each other, so that they both have fuller valence shells.
 
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dLj

.
Mar 23, 2017
1,758
Belliure 41 Snug Harbor, Lake Champlain
So, Collier stated that an element's most stable state is when it has neutral charge. All elections fill its valence with no extra.
Not exactly - Elements are most stable when in their lowest state of energy. This lowest state of energy as multiple components; charge neutrality is one, another is valence state satisfaction (for lack of a better term). These are the two we are concerned about here.

If you add or subtract electron to an outer shell, you will change the state of charge as you get imbalance between the protons in nucleus and the number of electrons. That is destabilizing to some extent. You have a competing "desire" to have your outer shell "filled" according to that shells "filled" state of electrons. See the periodic table and note the s and p etc shells - if you look at the last column to the right (top element is He) that column shows the filled outer shell state along that row.

Now, instead of adding or subtracting electrons to the outer shells to fulfill the desire to have a full outer shell, but now creating charge imbalance, your element can go find another atom that has the correct outer shell configuration to fill the outer shell, although shared with another atom. That is a "happy' state (lowest energy state). See what I mean?

A bonded molecule may be covalently bonded or chemically bonded. A chemical bond differs from covalent bonding in that two atoms joined by a covalent bond share electrons in their valence.
Get rid of the "chemically bonded" term. The concept was covalent bonds or ionic bonds. They are both a kind of chemical bond, but have notable differences between them.

Both atoms need to be positively charged (missing electrons) and two atoms joined by chemical bond means one atom needs to be negatively charged while the other is positively (one atom is missing electrons while the other has too many electrons). Chemically bonded atoms don't share valence electrons.
I'm not sure what your question is above. Both atoms do not need to be positively charged. In ionic bonds, the example in the book was NaCl - these two atoms are completing the "desire" to fill their outer shells by joining together through sharing the free, or missing depending upon if its the Cl or the Na, outer shell electrons.

Does this make for a weaker bond?
Ionic bonds are weaker than covalent bonds - their may be exceptions to this, but I can't think of any off the top of my head...

How does an atom get to be negatively charged without adding another electron shell?
It doesn't - you have to add an electron.

To add to our list of definitions, Collier says Ions are charged atoms or molecules, either negatively or positively.

It is these ions that we are really concerned with regarding corrosion.

-Will (Dragonfly)
That's part of the concern. Gotta run to work..

dj
 
Oct 19, 2017
6,850
O'Day 19 Littleton, NH
I think I'm beginning to understand.
Thanks.
I was thinking that charge balance only occurred with full valence shells. That the number of shelters was determined by the number of protons: one proton, one shell, two protons, two shells, etc.
Is the charge between proton and electron one-to-one? Is there charge balance with, 5 protons and 5 electrons, 2 in the inner shell, 3 in the shell?

-Will (Dragonfly)
 
May 17, 2004
3,374
Beneteau Oceanis 37 LE Havre de Grace
Is the charge between proton and electron one-to-one?
Yes, exactly. Iron, for example, has 26 protons and 26 electrons, so it is charge neutral. 8 of the electrons are in the valence shell, so it isn’t full, so it’s not not that “happy” (low energy). Combine it with oxygen, and they can share their electrons, getting to a lower energy (“happier”) state.
 
Feb 14, 2014
5,560
Hunter 430 Waveland, MS
No takers to answer?

HELIUM

Jim...

PS: Not Gold or Platinum they are fairly stable but not.
 

dLj

.
Mar 23, 2017
1,758
Belliure 41 Snug Harbor, Lake Champlain
I was thinking the answer was going to be something like "Unobtainium" That magical element that works perfectly in every situation, never breaks, degrades, or corrodes and is perfect for all applications...

dj
 
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Oct 22, 2014
15,695
CAL 35 Cruiser moored EVERETT WA
"Unobtainium" That magical element
I looked but did not see it on the periodic table. How many electrons, atoms, and neutrons? No way to tell if it is stable without the details.
 

dLj

.
Mar 23, 2017
1,758
Belliure 41 Snug Harbor, Lake Champlain
I looked but did not see it on the periodic table. How many electrons, atoms, and neutrons? No way to tell if it is stable without the details.
Yeah, that's kinda the problem. Scientists and engineers have been looking for it for years but it remains illusive... ;)

dj
 
Oct 22, 2014
15,695
CAL 35 Cruiser moored EVERETT WA
I don’t know about the “unobtainium”.

But I have found, while searching along some lakeside shores up here in the PacificNW, a rock with interesting properties. Geologists identify it as “Leaverright”.

When found near water it abrades easily forming a nearly flat round shape, imparting some aerodynamic properties. It has a hardness of 5 on the Mohs hardness scale. It has some magnetic properties yet does not affect a compass when in proximity.
 

dLj

.
Mar 23, 2017
1,758
Belliure 41 Snug Harbor, Lake Champlain
I'm guessing it's the cause of some kinds of unexpect groundings that have no other rational cause other that we think there was some leaverright stones over there causing boat attraction that couldn't be over come... I'll be learning a lot about sailing in the PNW this summer I see...

dj
 
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Apr 5, 2009
1,547
Catalina '88 C30 tr/bs Oak Harbor, WA
Whenever I have seen Leaverright, it has shown a propensity to spontaneously bounce on the water.
 
Feb 14, 2014
5,560
Hunter 430 Waveland, MS
I thought it was a joke!
I never joke about chemistry!

Seriously we should be discussing corrosion chemistry.

We have too much of this acid around out boats now.

Hydroxylic Acid

Needed to promote Galvanic Corrosion and can burn, if hot vapors are inhaled.
Jim...
 
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