Energy Levels, Orbitals & Electron Configurations

Introduction

Electrons do not travel around the nucleus in neat, predictable orbits. Instead, they exist inside of something known as the electron cloud where it is impossible to predict their exact locations. The cloud is divided into different energy levels, with the lowest energies closest to the nucleus. The energy levels are then divided into something called orbitals. Orbitals are not orbits. They are the regions where electrons are most likely to be found.

There are four types of orbitals (called s, p, d and f) and each of the types has a different shape. We’re only going to work with the simplest shapes, the s and p orbitals.

After the first couple of energy levels, it becomes much too difficult to draw pictures of the different orbitals. This is when we use something called an electron configuration.

Questions

1) How many energy levels are in an atom of silicon?

2) How many energy levels are in an atom of silver?

3) How many energy levels are in an atom of sodium?

4) How many energy levels are in an atom of helium?

5) Which types of orbital would hold electrons in a hydrogen atom?

6) Which types of orbital would hold electrons in a sulfur atom?

7) How many s orbitals are in an atom of beryllium?

8) How many s orbitals are in an atom of sodium?

9) How many p orbitals are in an atom of boron?

10) How many p orbitals are in an atom of carbon?

11) How many p orbitals are in an atom of nitrogen?

12) How many p orbitals are in an atom of neon?

13) How many orbitals are there total in an atom of oxygen?

14) How many orbitals are there total in an atom of aluminum?

Pictures

15) Draw a picture of a beryllium atom.

16) Draw a picture of a carbon atom.

17) Draw a picture of a oxygen atom.

18) Draw a picture of a sodium atom.

Electron Configurations

Write the electron configuration for each of the following atoms:

19) helium

20) beryllium

21) carbon

22) neon

23) sodium

24) chlorine

25) calcium