## Assignment: The Periodic Table and Electron Configurations

### The Periodic Table

Ptable.com is a great resource for double-checking your understanding of electron configurations and periodic trends, so let’s get some practice using it:

1. Go to www.ptable.com and explore the features.
2. Select an element and explore each tab for your chosen element.
3. Record 5 properties of the element – including the size of the atom and its electronegativity.
4. Draw the electron configuration of a neutral atom of that element.
5. Find the number of possible isotopes for your element and the number of naturally occurring isotopes. Record the most common isotope in proper form.
6. Combine your element with another to create a compound. Write down the third result for the combination of these two atoms.

### Electron Configurations and Trends

Answer these discussion questions.

1. Given the following part of an electron configuration, 3s2, explain which part refers to the number of electrons, the energy level and the sublevel.
2. What is the maximum number of electrons that can occupy a single orbital?
3. State and explain Hund’s Rule.  Write the electron configuration (orbital notation) for nitrogen using this rule.
4. For each of the following electron configurations, name the element:

a)       ↑↓1s _↑↓2s    __↑↓_ _↑↓__ _↑__2p

b)       __↑↓_ 1s __↑↓_2s    __↑↓_ __↑↓_ _↑↓_2p   _↑↓__3s   __↑↓_ __↑↓_ __↑↓_3p   _↑↓__4s  _↑__ __↑_ __↑_ _↑_ __↑_3d

1. Write the electron configurations using noble gas notation for the elements in Group 2 of the periodic table.
2. Write the electron configurations for Period 1 elements.  What is the relationship between the period number and the energy level of the valence electrons?
3. On the Periodic Table below, draw circles to represent the trend in atomic size for:

a) a group

b) a period