Advice for when you need to guess at a reason for chemical properties

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DraconisAudiat
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#1
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"The size of the ions"

A surprising number of chemical properties of atoms all across the periodic table can be explained with some variation of "The size of the ions".

Just saying that on its own won't get you the points in most situations but it'll be a good starting point for when you need to think about it on the fly to make up a reason.

Example:
Q: Why is Fluorine more reactive than Iodine and elements further down group 7?
A: Fluorine is small so the outer electrons are closer to the nucleus which makes it easier to gain a new electron, Iodine is larger and has more filled shells of electron shielding so the outer electrons aren't held as well so it's harder to gain a new electron.

A lot of explanations are variations on charge density, electronegitivity or atomic radius. Which you can think of as being "The size of the ions" but don't right that on its own.

Remember atomic radius DECREASES as you go Right in the periodic table, despite having more electrons the nucleus has more protons so it pulls in the electrons more strongly so the radius shrinks.
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Pigster
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(Original post by DraconisAudiat)
"The size of the ions"

A surprising number of chemical properties of atoms all across the periodic table can be explained with some variation of "The size of the ions".

Just saying that on its own won't get you the points in most situations but it'll be a good starting point for when you need to think about it on the fly to make up a reason.

Example:
Q: Why is Fluorine more reactive than Iodine and elements further down group 7?
A: Fluorine is small so the outer electrons are closer to the nucleus which makes it easier to gain a new electron, Iodine is larger and has more filled shells of electron shielding so the outer electrons aren't held as well so it's harder to gain a new electron.

A lot of explanations are variations on charge density, electronegitivity or atomic radius. Which you can think of as being "The size of the ions" but don't right that on its own.

Remember atomic radius DECREASES as you go Right in the periodic table, despite having more electrons the nucleus has more protons so it pulls in the electrons more strongly so the radius shrinks.
Your post routinely confuses 'atomic radius' with 'ionic radius'. They are not the same as each other and answers would be heavily penalised if any confusion were implied or stated. Sodium's ionic radius is smaller than its atomic radius, whereas fluorine's ionic radius is bigger than its atomic radius.

Electronegativity will seldom be relevant for questions such as your example.

One should never "make up a reason".
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DraconisAudiat
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I mean electronegativity is often the reason for a property / reaction, either that or charge density and charge density IS due to The Size Of The Ions.
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