Here are the answers to my last blog, 27th July 2012
The electron arrangements of sodium and chlorine are as follows:
Na 2,8,1 Cl 2,8,7
When sodium reacts with chlorine the outer electron from sodium is transferred to the outer electron shell of chlorine.
Two ions are formed during the reaction (transfer process), Na+ and Cl-.
The electron arrangements of the two ions are:
Na+ 2,8 Cl- 2,8,8
So which members of the nobility do the two ions copy with their electron arrangements?
Here’s the answer to my last blog, 25th July 2012
Why do atoms go free but ions don’t? Because atoms have no charge. Ions on the other hand are charged particles.
So how do sodium and chlorine atoms become ions when they react to make sodium chloride?
Dot and cross diagrams for sodium and chlorine
When atoms react, they do so to gain a full outer shell of electrons and so become more stable (like the nearest noble gas). For sodium and chlorine this means they will react to get 8 electrons in their outer shells.
Given that the atoms could either gain or lose electrons, what is the easiest way for sodium and chlorine to each get 8 electrons in their outer shell?
The answer to my last blog, earlier today, 25th July 2012
When is a crystal not a crystal? Whan its a glass!
Glass is an amorphous solid and does not have a regular crystal lattice structure.
However, it is a solid and not a very viscous liquid as the urban legend about very old glass in the windows of churches might have it. Wikipedia gives a good account of the stories and the way early glass was manufactured and used.
So how come atoms go free, but ions don’t?
Here are the answers to my last blog, 23rd July 2012,
Definitions of the words crystal and lattice:
A crystal is a solid material, with a regular three dimensional, repeating pattern to its structure. The dictionary definition adds that crystals have symmetrically arranged plane faces.
I usually say to my students crystals have flat surfaces and sharp edges. For example, sodium chloride forms a regular cubic structure in its crystals. They’re cubes!
Examples of lattices are a lattice fence and a lattice crusted pie. In both of these examples lattice refers to a criss-cross arrangement of strips (wood or pastry).
The word lattice applied to crystals means a regular, patterned structure. Again if you look it up in a dictionary it says a crystal lattice is “a geometric arrangement of the points in space”. In the case of sodium chloride the “points” are the sodium and the chloride ions.
There’s an old joke which goes “When is a door not a door?”
The answer is “When its ajar”.
Ajar means slightly open.
So “When is a crystal not a crystal?”
Here are the answers to my last blog, 22nd July 2012
Each sodium ion (Na+) is surrounded by six chloride ions (Cl-). And each chloride ion is surrounded by six sodium ions. Since there are equal numbers of sodium and chloride ions the formula is NaCl.
Sodium chloride is held together by ionic bonds. An ionic bond is an electrostatic attraction between oppositely charged ions in a crystal lattice.
Hence, in sodium chloride each sodium ion, Na+, is attracted to the six chloride ions, Cl-, that surround it. And similarly, each chloride ion is attracted to the six sodium ions that surround it.
Phew! That was a lot of reading. So here’s my favourite picture of sodium chloride illustrating the cubic structure of the crystals.
What is a crystal? And why is the structure of ions in sodium chloride described as a crystal lattice? What is a lattice?
The shadows cast by the crystals really bring out their cubic structures into sharp relief.
Here’s the answer to my last blog, 21st July 2012
Sodium chloride, NaCl is common salt.
Sodium chloride consists of a three dimensional lattice of Na+ and Cl- ions. So what holds the lattice of ions together in the salt crystal?
Here’s the answer to the last blog (20th July 2012)
So, now can you explain…
Why did the electron cross the road?
What is the product when the electron crosses over from sodium to chlorine?
Mr Atom finds his centre.
Hello, this is my first attempt at a blog. I’m a chemistry teacher and I’m going to draw some chemistry doodles for fun. Can you work out the first name of Mr Atom?
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