Ionic and Covalent Bonding Cheat Sheet by fongrsy

• Atoms like Noble Gases do not combine with other atoms because they have stable electronic structures

• All other atoms bond during chemical reactions in order to have a Stable Noble Gas Config­uration

• Bonding only involves the valence electrons

• Valence electrons are respon­sible for the chemical properties of an atom

• Atoms of metals have few valence electrons (1-2) thus they tend to lose electrons to form positive ions (cations).

• Atoms of non-metals have many valence electrons (4-7) thus they tend to gain electrons to form negative ions (anions).

• In this way, they obtain the electronic config­uration of a stable noble gas.

• Ionic bonding is the electr­ostatic forces of attraction between oppositely charged metal cations and non-metal anions.

• Ionic bonding occurs between 1 METALLIC atom and 1 or more NON-ME­TALLIC atoms.

• It involves the TRANSFER OF ELECTRONS from a metal atom to a non-metal atom to achieve a stable noble gas config­ura­tion.

• This results in the formation of oppositely
charged IONS.

• A covalent bond occurs between 2 or more NON-ME­TALLIC atoms.

• It involves the SHARING of one or more pair/s of electrons between the non-me­tallic atoms to achieve a noble gas electronic config­ura­tion. This results in the formation of MOLECULES.

• The bonds can be formed between atoms of the same elements or between atoms of different elements.

• A COVALENT bond is the electr­ostatic forces of attraction between the nuclei of the 2 atoms and the pair of shared electrons.

1. Write down the formula of the compound and the electronic config­uration of the atoms.

2. Look at the valency of the atoms and determine how many need to be transf­erred.

3. The cation loses all its valence electrons while the anion gains electrons until both ions obtain a stable noble gas config­ura­tion.

4. Draw circles to represent the electron shells and dots/c­rosses to represent electrons. (Do not forget to write the element's formula in the centre of the circle.)

5. For the anion, use the symbol (dots or crosses) that you used for the cation to represent the number of ions transf­erred from the cation to the anion.

6. Remember to draw brackets, write the number of atoms before the brackets, and write the charge to the top right of the bracket. (e.g 3+)

1. Write down the formula of the compound and the electronic config­uration of the atoms.

2. Look at the valency of the atoms and determine how many need to be shared.

3. For compounds of a single element like Cl2 or N2, the number of bonds that need to be shared is the number of electrons it needs to become stable. (E.g for N2, it has 5 valence electrons and needs 3 more to become stable, therefore it has 3 pairs of shared electr­ons.)

4. For compounds made of multiple elements, determine how many bonds are required for all elements to become stable. Note that 1 pair of shared electrons = 1 more electron for the atom.

5. Draw circles to represent the valence electron shells and dots/c­rosses to represent the valence electrons. Note that the circles have to intersect so there is space to draw shared pairs of electrons.

6. Draw the valence electrons on the circles and the shared pairs of electrons in the inters­ection.