Polarity

This is only slightly more complicated due to the molecules/ions with 5 (or 6) regions of electron density around the central atom.

Lewis Dot Diagrams Recap

We went over the steps to draw these, and a few examples:

Shapes of Molecules

Today, we were introduced to the shapes of molecules/ions with 5 or 6 regions of electron density. Thank you to Ella, Bronwyn and Sarah for remembering to bring the lollies and toothpicks to make our models with!

Source: http://figures.boundless.com/10397/full/vsepr-geometries.png

Lewis Dot Diagrams

We started with a recap of Level 2 Chemistry:

Then, we learned about some examples which break the Octet Rule:

Finally, we learned about how to do Lewis Dot Diagrams for polyatomic ions:

Today was #PinkShirtDay in NZ; a day to raise awareness of, and express intolerance for bullying. #StopBullying

Electronegativity

Today was primarily a recap of Level 2 work. However, as well as knowing how to use E.N. to predict bond type, we also need to remember two trends and to justify them using our knowledge of atomic structure.

Below is the video of the key considerations being summarised for the class in 2013:

Transition Metals

Transition metals have some characteristic properties. We need to be able to explain these in terms of their atomic structure (radius and/or electron configuration).

Ionisation Energy

Ionisation Energies are often used as further evidence to determine the structure of atoms, particularly their electron configurations. Trends in 1st Ionisation Energies also tell us a lot about the different orbitals and their relative distances from the nucleus.

Electron Configurations

The Bohr Model was useful in explaining the properties of the first 20 elements but falls down beyond Calcium. To understand the properties of the transition metals and other elements up to Krypton (36), we need to understand s, p and d orbitals.

• s orbitals can hold up to two electrons
• p orbitals can hold up to six electrons in 3 sub-orbitals
• d orbitals can hold up to ten electrons in 5 sub-orbitals

The next thing to get our heads around is how to write the electron configurations for ions. We came up with the "penguin" theory (thanks Bronwyn!!). The penguins on the edge of the ice-pack get taken away by the seals first... The electrons farthest from the nucleus are removed first when cations are formed.

For homework, we have to write the electron configurations for:

1. copper (II)
2. iron (II)
3. iron (III)
4. zinc

We also have to infer why zinc ions form colourless/white compounds.

Planning Ahead

The image below shows a brief overview of what we will be covering in the next few weeks, and a more detailed plan of what content will be covered in the first few lessons:

Atomic and Ionic Radius

We started today by revisiting the Bohr Model of the atom, as it can be used to explain trends in atomic and ionic radii.

We are expected to be able to answer all of these types of questions before we move onto the next concept.