Valence Electrons & Forming Ions
Chemistry: IB Diploma Higher Level, topic 2.6.1
Valence Electrons
Valence electrons are the electrons in the outermost energy level. Ionic compounds can be formed through the transfer of valence electrons between a metal and non-metal.
Bonding
- Valence electrons are the electrons held in the outermost energy level of an atom.
- They are transferred from metals to non-metals to create an ionic bond.
- Atoms will gain or lose electrons in order to achieve a noble gas electron configuration.
- Noble gases are the most stable atoms and contain eight electrons amongst their s and p orbitals, with the exception of Helium which has 2 valence electrons.
Metals
- Metals are located to the left of the metalloids on the periodic table and lose their valence electrons to achieve a noble gas electron configuration.
- When a metal loses electrons, it becomes positively charged.
- Neutral atoms have an equal number of protons and electrons and so if an atom loses electrons there will be a surplus of positive charge.
- When a metal loses electrons and forms a positive ion it is called a cation.
Non-metals
- Non-metals are to the right of the metalloids and gain electrons into the outermost energy level to achieve a noble gas electron configuration.
- When a non-metal gains electrons, it becomes negatively charged and is called an anion.
Forming a bond
- The metal will lose electrons and the non-metal will gain them.
- This creates a bond through electrostatic forces of attraction between the positively and negatively charged ions.
- Presto, we have an ionic bond.
The periodic table
- The number of valence electrons an element has can be figured out by looking at which group in the periodic table the element is in.
- For example, all the elements in Group 7 have 7 electrons in their outershell.
Test yourself on Valence Electrons & Forming Ions
In which energy level of an atom are valence electrons held?
What kind of attraction holds the oppostiley charged ions together in an ionic bond?