Ionic Bonds
Essential Question:
How do ionic bonds form?
What is an Ion
• An ion is any atom or combination of atoms
that has a charge, negative or positive.
• An ion is formed when electrons are add or
taken away from an atom.
• They are never formed by protons being
added or removed, NEVER.
• Opposite charges of atoms attract each other.
Why do Ions form?
• Ions form because atoms want to have a
complete octet.
• An Octet is 8 electrons in the outer energy
level or shell.
• How can we make complete shells?
How Ionic Bonds Form?
• An ionic bond is the force of attraction that holds
together positive and negative ions.
• It forms when atoms of a metallic element give up
electrons to atoms of a nonmetallic element.
Ions
• When an atom loses a
negative electron, the
overall charge becomes
positive
• It’s called a cation
• When an atom gains an
electron, the overall charge
becomes negative
• It’s called an anion
Table Salt
• Sodium and Chlorine
have equal and
opposite charges.
• They “attract” and cling
together in a strong
ionic bond.
• Ionic bonds form
between metal and
nonmetal atoms
Why Ionic Bonds Form
• Ionic bonds form only between metals and
nonmetals. That’s because metals “want” to give
up electrons, and nonmetals “want” to gain
electrons.
• Look at the Lewis Dots that you drew on your
Periodic Table & think about the Octet Rule
• Alkali Metals (#1) bond with Halogens (#17)
• Predict which might bond with Alkaline Earth
Metals
• Alkaline Earth Metals (#2) bond with the Oxygen
Family (#16)
Energy and Ionic Bonds
• Energy holds the electrons in orbit around the
nucleus
• Energy is needed to remove valence electrons
from one atom and attach them to another
• These ionic bonds are very strong and difficult to
break – for example, try burning salt
• These compounds have high melting and boiling
points and are good electrical conductors.
• Because water has polar bonds, ionic compounds
do dissolve in water.
Ionic Bonds form Crystals
• Many compounds form
molecules, but ionic
compounds form crystals
instead.
• A crystal consists of many
alternating positive and
negative ions bonded
together in a matrix.
Ionic Crystals
• In this demo, we will cause a minor chemical
reaction of several metals and nonmetals:
• We’ll use table salt, which contains Sodium
and Chlorine
• “Bluing” which contains Ferric
hexacyanoferrate which has Iron, Nitrogen,
Carbon, and Oxygen
• Water = Oxygen and Hydrogen
Ionic Crystals Demo
• In a glass or plastic bowl, put some pieces of
charcoal, porous brick, tile, cement or sponge.
Day 1: Over the base material, 10 ml of water, 10
g salt and 10 ml Mrs. Stewart's Bluing.
Day 2: Add two more tablespoons of salt.
Day 3: Pour into the bottom of the bowl (not
directly on the base material) two tablespoons
each of salt, water, and Mrs. Stewart's Bluing, and
then add a few, vegetable coloring each piece.
Observe over the next few days…
• Next week, we’ll discuss covalent bonds and
create a polymer.
• You will be asked to compare and contrast the
result of these two activities.