Tag: atoms and molecules

Electron Configuration Practice

A quick electron configuration practice webpage that lets you enter the symbol for an element and see if you can write out the electron configuration in both the full and noble gas forms.

Screen capture from the electron configuration webpage. Sulfur (S) is entered, and then the long form and noble gas form of the configurations can be entered and checked. In this case, there is an error in one part of the noble gas form.

The table at the bottom is a guide to filling the electron shells and orbitals. You can click any of the blue squares to change the number of electrons in the orbital.

Update

An improved version of the lower, table part is here.

Atom Board: Montessori Work

Carbon-14 using the atom board.
Carbon-14 using the atom board.

These atom boards worked very well for practicing how to interpret atomic symbols. The protons (blue) and electrons (red) are magnetic so they snap into place quite satisfyingly. Their poles are oriented so that the electrons will only attach properly to the slots in the electron shells and the protons only attach the right way up to the nucleus. The neutrons are wooden and non-magnetic.

Procedure for Building an Atom

Nucleus

Step 1: Number of protons (+ charge).

  • The number of protons is given by the element name. Carbon will always have six protons, Hydrogen will have one proton. I have students memorize the first twenty elements in the correct order, so they can quickly determine the atomic (proton) number.
  • 14C: Protons = 6+

Step 2: Number of neutrons.

  • Neutrons = atomic mass – number of protons
  • The atomic mass is given at the top left corner of the atomic symbol: 14 in the example above for 14C.
  • 14C: Neutrons = 14 – 6 = 8

Electron Shells

Step 3: Number of electrons (- charge).

  • Electrons = number of protons – charge
  • The charge is given to the top right of the atomic symbol. In this case, there is no charge
  • 14C: Electrons = 6 + 0 = 6

Step 4: Electron Shells

  • Electrons go in shells around the nucleus.
  • Start with the smallest shell, fill it, and then add the next shell until you’ve placed all of the electrons.
  • The first shell can hold only 2 electrons, the second shell can hold 8, and the third 8. The electron configuration tells how many electrons are in each shell.
  • 14C: Electron configuration: 2-4

Building atoms with the atom board.
Building atoms with the atom board.

They’ve also turned out to be useful when explaining ionic bonding. Since it’s easy to add or remove electron shells, you can clearly show how many electrons can be donated or received to figure out how many atoms are involved in the reactions.

Molar Mass of Molecules

Calculate the molar mass of a molecule:

The notation for the chemical formula is a little funky: you put the element symbol and then the number of atoms separated by a colon; each element/number of atoms pair are separated by commas, so sodium chloride (NaCl) would be “Na:1,Cl:1“.

This will have to do until I can write something to parse the regular chemical formula notation.

On the plus side, you can link to a specific molecular mass calculation by adding the formula to the url. So magnesium chloride (MgCl2) can be found with this url:

https://soriki.com/js/chem/chem_db/molecular_mass.html?formula=Mg:1,Cl:2

Updated Atom Builder

A couple of my students asked for worksheets to practice drawing atoms and electron shells. I updated the Atom Builder app to make sure it works and to make the app embedable.

So now I can ask a student to draw 23Na+ then show the what they should get:

Worksheet

Draw diagrams of the following atoms, showing the number of neutrons, protons, and electrons in shells. See the example above.

  1. 14C: answer.
  2. 32K+: answer.
  3. 18O2-: answer.
  4. 4He2+: answer.
  5. 32P–: answer.

I guess the next step is to adapt the app so you can hide the element symbol so student have to figure what element based on the diagram.

3d Molecule Viewer

An excellent 3d viewer for molecules.

An excellent 3d molecule viewer. (The actual app has a lot smoother animations than this.)
An excellent 3d molecule viewer.

In addition to the existing molecules, you can import any number of others if you can find them in one of the right formats (PDB, SDF or MOL molecule definitions): the ligand.info: Small Molecule Meta Database is a good source for SDFs.