Saturday, April 8, 2017

Mass Number and Number of Neutrons

What is the mass number of an atom?
Why is it called a "mass number"?
How many nucleons are in an atom of an element?
How many neutrons will you find in the nucleus of an atom?

These are all good questions, which is why AUS-e-TUTE has just added new resources to help you understand and answer these questions.
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A "free-to-view" mass number tutorial with worked examples is currently available at

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Saturday, March 18, 2017

How Many Electrons in an Atom?

For an atom of an element:
number of electrons = number of protons = atomic number of element

AUS-e-TUTE has a new tutorial, game, test and drill to help you learn and apply this idea.
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If are not an AUS-e-TUTE Member, there is a "free-to-view" tutorial currently available at:

Saturday, March 11, 2017

How Many Protons in an Atom?

number of protons in an atom = atomic number (Z) of the element

... and.... the periodic table of the elements lists the elements in or order of increasing atomic number!

Now, if you'd like to see AUS-e-TUTE's new tutorial on this topic, along with worked examples of exam questions, you will need to visit

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Sunday, March 5, 2017

World Science Festival Brisbane

World Science Festival is on in Brisbane between March 22nd and 26th 2017.
You can download the program guide here

This event has been advertised as exploring four themes:
  1.  Physics + Space – the study of matter and its motion through space
  2. Oceans – the health of our marine environment and the challenges facing water supply and sustainability
  3. Energy – alternatives, supply and diversification
  4. Robotics – engineering, computers and artificial intelligence.
If you are interested in "chemistry" then the pickings are slim and somewhat grim. Chemistry is, as usual, painted as the evil villain:
  • chemistry kills the oceans as a result of industrialisation (acidification, climate change, plastic pollution) ... but "smart engineering" might be the hero of the piece
  • chemistry kills marine ecosystems as a result of the break-up of plastics into "microplastics", but a panel of leading "environmental thinkers" will be discussing what to do about it
  • chemistry gave us, presumably, "dirty energy"  when we learnt how to control the combustion of fossil fuels, but once again "smarter technologies" will lead to "clean energy" and "revolutionary" technology will make renewable energy more reliable apparently.
 I'm a little uncertain of how, when or why "engineering" and "technology" are seen in such a positive context, while chemistry seems to be painted as the evil sibling out to do as much damage to the environment and society as possible.
Similarly if you want to inspire your female students to take up further studies in chemistry, I don't think you're going to find much motivation here .... while Marie Curie is mentioned along side Jane Goodall (primatologist)  and Mary Jackson (aeronautical engineer), the participants in the discussion are Emma Johnston (marine ecologist), Suzanne Miller (marine geologist) and Kerrie Wilson (ecologist). I may be wrong, but it seems to me that women are well represented in the "marine science" and "biological science" areas.

If you are interested in "physics" then the "Gravitational Waves - A New Era of Astronomy" might be worth the $30-$35 ticket.

And ..... just a reminder .... you only have until 25th April 2017 to visit the Large Hadron Collider Exhibition at the Queensland Museum .... and yes, that is really a worthwhile trip. The exhibition is fabulous!

Intravenous Anaesthetics

In the eighteenth century surgery was limited to essential operations, such as the amputation of gangrenous limbs, performed on conscious patients who were strapped in and held down by assistants.
By the mid-nineteenth century gases like ether and chloroform were being used to reduce pain during dentistry and childbirth. Then the hypodermic syringe was developed, allowing drugs to be injected directly into the blood stream resulting in drugs that acted quickly and predictably.
But it wasn't until the early twentieth century that intravenous anaesthetics, compounds that cause loss of consciousness, became available and revolutionized surgery. 

Discover some chemistry of intravenous anaesthetics in this issue of AUS-e-NEWS

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Sunday, February 12, 2017

The First Helium Compounds

Can helium form compounds?
Helium, He, is the first Group 18 element or Noble Gas element.
In the nucleus of a helium atom there are 2 protons, and surrounding the nucleus there are just 2 electrons. These 2 electrons complete the first energy level and require large amounts of energy to remove. For this reason, an atom of helium is very stable and does not undergo chemical reactions on Earth.
But what if you tried to react helium, a non-metal, with a highly reactive metal, such as sodium, at extremely high pressures (greater than 113 GPa)?
Utah University Chemists predicted that under these conditions helium and sodium would form a compound. Then, high pressure synthesis in a diamond anvil actually produced a stable compound with the formula Na2He.
On the left hand side is a "ball and stick" model of Na2He in which the purple balls represent sodium and the white balls represent helium.You can see that the structure is cubic.
On the right hand side is a polyhedral representation of Na2He in which sodium atoms form the cubes (Na8). Half of these cubes are occupied by helium atoms, and these are shown as grey boxes. But the other half of the cubes are occupied by 2 electrons and these are shown in the diagram as red spheres.
The chemists are predicting that other compounds of helium may also be possible, such as Na2HeO.

 Utah State University. "Up, up and away: Chemists say 'yes,' helium can form compounds: Helium and sodium form stable compound at high pressure." ScienceDaily. (accessed February 12, 2017).

Further Reading:
Introduction to the Modern Periodic Table 
 Bohr Model of the Atom 
Evidence for Electron Configuration of an Atom
Subshell Electronic Configuration

Suggested Study Questions:
  1. What is the atomic number for
    • helium
    • sodium
  2.  How many electrons are present in an atom of
    • helium
    • sodium
  3.  Write the simple electronic configuration for an atom of each element below:
    • helium
    • sodium
  4.  Write the electron configuration for an atom of each element below using subshell notation:
    • helium
    • sodium
  5. Write an equation for the loss of an electron from a gaseous atom of sodium. 
  6. Give the simple electronic configuration for the ion of sodium produced above.
  7. Give the electronic configuration of the sodium ion produced above in terms of subshells.
  8. Explain why the first ionisation of helium is so much higher than the first ionisation energy of sodium.
  9. Explain why sodium readily forms compounds.
  10. Explain why it is extremely difficult to produce helium compounds, and why it has required such enormous pressures in order to produce the first helium compound.

Friday, February 3, 2017

Isoelectronic Species

What do we mean by two or more species being isoelectronic?
What are some examples of isoelectronic species?
I'm glad you asked!
AUS-e-TUTE has just added a new tutorial, game, test and exam to help you understand this.
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Not a member?
A "free-to-view" tutorial is currently available for evaluation purposes at: