Electron Shells and Bonding
The electrons in an atom are arranged
in Shells around the nucleus. These
shells are also known as electron
Orbital or Energy
Levels. The Lowest energy level is always
filled first - the most inner shell. Each shell can hold only a limited
number of electrons The first shell can only hold
2 electron - lowest energy level. The Second shell up to 8 electrons. The Third can also hold up to
8 electrons etc. Atoms with their outer shell full
of electrons, do not react with anything. They are very stable. Most atoms do not have their outer
shell full of electron and this is what makes them want to react Other
then the NOBLE
GASES, the atoms of all other
elements have incomplete outer shells. That is why they react. For any atom to
become stable it must
have its outer shell full of electrons 8 of the with the exception of Hydrogen
and Helium, which only require 2 electrons. They can do this in two different ways: By losing or gaining electrons or
- ionic bonding By sharing electrons - covalent bonding Ionic Bonding - it is all about atoms losing or gaining electrons to become stable,
i.e. (have their
outer shell full of electrons). Remember ! A
full outer shell makes an atom stable. During ionic bonding,
atoms gain or lose electron(s) to form stable negatively (-Ve) or positively (+Ve) charged ions which are then strongly
attracted to one another to
form an IONIC
BOND. Ionic
bonds form between metals and non-metals. Most metallic elements lose electrons to form a POSITIVE
ION. Most non-metallic elements gain electrons to form a NEGATIVE
ION. An ION is a charged particle (not an atom any more). It is charged because it contains an unequal number of protons and electrons. Let's look at sodium chloride as an example:
Atomic Bonding:
Some facts:
Water Bond:
Test your understanding of ions, electron transfer, and lattice structures based on the lesson content. 1. What happens to a metal atom when it forms an ionic bond? 2. Why do atoms transfer electrons during ionic bonding? 3. Which force holds the ions together in an ionic compound? 4. In a dot and cross diagram of Sodium Chloride (NaCl), what does the 'cross' usually represent? 5. Which of the following best describes a 'giant ionic lattice'? 🧪 Knowledge Check: Ionic Bonding
Click to Reveal Answers
2. To achieve a full outer shell (This results in a stable electronic arrangement like a noble gas).
3. Electrostatic attraction (The strong force between positive and negative charges).
4. An electron from one of the atoms (Dots and crosses distinguish which atom the electrons originated from).
5. A regular, repeating 3D structure (This structure is formed by millions of ions in a fixed pattern).