Ionic and Covalent Bonding
Chapter 4 – Section 2
Pg. 116 - 122
• Atoms with unfilled valence shells are
• Atoms will try to fill their outer shells by
bonding with other atoms.
• The number of valence electrons will
determine how many bonds the atom can
• Two types of bonds we will discuss:
– Ionic bonds
– Covalent bonds
• Ions are charged atoms (positive or negative).
• Ions are formed when atoms gain or lose
• Positive ions are called cations.
– Formed when the atom loses electrons.
• Negative ions are call anions.
– Formed when the atom gains electrons.
• Ionic bonds are formed between metals
• Ionic bonds are formed between
oppositely charged atoms (ions).
• Ionic bonds are formed by the transfer of
– One atom donates electrons to the other.
Ionic Bonds (continued)
• In an ionic bond one atom will lose its electron(s)
and the other will gain them.
– Depends on the number of valence electrons.
• The transfer of electrons creates a positive ion
and a negative ion.
• The opposite charges attract one another,
causing a bond to form.
Drawing Ionic Bonds
• We can illustrate ionic bonding using
• 1 – Draw the Lewis structure for each
– Ex: Na Cl
• 2 – Draw arrows to show the gain/loss of
Drawing Ionic Bonds (continued)
• 3 – Draw ion Lewis diagrams showing the
new charge for each ion.
• The chemical formula for the compound
formed represents the ratio of negative
ions to positive ions.
– Ex: NaCl – for every 1 sodium ion, there is
also 1 chlorine ion.
Practice Drawing Ionic Bonds
Elements Lewis Ion Lewis Formula
• Covalent bonds form between two non-
• Covalent bonds are formed when atoms
– Both atoms need to gain electrons, so they
share the electrons they have.
• Atoms can share more than one pair of
electrons to create double and triple
Covalent Bonds (continued)
• Atoms can share their electrons equally or unequally.
• When atoms share electrons equally it is called a non-polar
– Non-polar covalent bonds form between atoms of the same type. Ex:
• When atoms share electrons unequally it is called a polar
– One atom pulls the electrons closer to itself.
– The atom that pulls the electrons more gets a slightly negative
– The other atom gets a slightly positive charge.
• Ex: Water molecule
Drawing Covalent Bonds
• We can illustrate covalent bonding using
• 1 – Draw a Lewis structure for each element.
– Ex: C H
• 2 – Draw circles around the shared pair(s) of
• 3 - Continue adding atoms until all atoms
have a full valence shell.
Practice Drawing Covalent Bonds
Elements Lewis Formula
Ionic Vs. Covalent Bonds
Ionic Bonds Covalent Bonds
• Form when electrons • Form when electrons
are exchanged are shared between
between atoms. atoms.
• Form between a • Form between two
metal and a non- non-metals.
Both types of bonds result in all atoms
having a full outer energy level.