Uploaded by makofane.t.clement

23 04 2022

DATE: 23 April 23, 2022
Matter and Material NOTES
A Chemical bonds
is a mutual attraction between two atoms resulting from the
simultaneous attraction between their nuclei and the outer
- In simple terms we can say is the bond that hold atoms
together into molecules.
- We have difference kinds of chemical bonds, but we have
primarily three types of bonds
◼ Ionic Bonding
A common example is Sodium Chloride (NaCl)
◼ Covalent bonding
A common example is water molecule (𝐻2 𝑂)
◼ Metallic bonding – it is self-explanatory, it is a bond between
metal elements.
However, in grade 10 you already did Metallic and Ionic bonds
thoroughly, if you forgotten them, I suggest you revise them.
Molecular structure
Important terminologies
1. Electronegativity – Is a measure of the tendency of an atom in
a molecule to attract bonding electrons.
2. Bond polarity – Is the separation of electric charge from a bond,
leading to a molecule or its chemical group having an electric
dipole or dipole moment. (This is because electrons are not
always shared equally among two atoms or bonded atoms.
3. Bond energy – (of a compound) is the energy needed to break
one mole if its molecules into separate atoms.
4. Bond length – Is the average distance between the nuclei of
two bonded atoms.
5. Valence electron – are the electrons in the highest energy level
of an atom in which there are electrons. i.e., Outer electrons
Lewis dot diagram is a structural formula in which valence electrons
are represented by dot or crosses. It is also known as an electron dot
formula, a Lewis formula, or an electron diagram.
Look at the following examples of Lewis diagram.
Oxygen ion
Cobalt Oxide
NOTE: Atoms usually share electrons in a way that allows them to
satisfy the OCTET RULE.
Practice Questions:
1. How many valence electrons do group 17 element possess?
2. What is the difference between electron Shell and Electron
3. How does the number of valence electrons change as one move
from left to right on of the periodic table?
2. Electron Shell –is a way of grouping electrons surrounding the
nucleus of an atom.
Electron orbit – Is one the path of an electron around the nucleus of
an atom.
For more of the information analyze the following illustrations.
Electron Orbits – shows us
the level of electron
movements from level s to p,
for our level of educations.
Electrons Shells – always surround an
atom to show all electrons that make up
that atom.
Along site we have Carbon Atom.
You will do more questions in class.