YEAR 10 CHEMISTRY
CHEMICAL BONDING
WALT
 How and why atoms bond
together to form molecules
WILF

NAME
Draw diagrams of
covalently bonded
molecules (dot and
cross diagrams)
TASK A
Atoms are more stable if they have a full outer shell of electrons.
(1) The first shell holds _______ electrons when full.
(2) The second and third shells hold ________ electrons when full.
(3) Group 0 – the Noble gases have full out shells. Use the periodic table in the textbook to list
all the atoms with full outer shell.
If the atoms do not have full outer shells, they can get full outer shells, and become more stable by
sharing electrons. These atoms are BONDED together while sharing electrons.
(4) This is called ______________________ BONDING
(5) The dots and crosses represents
________________________
They are shown as dots and crosses to show
that they come from a different atom
(6) How many electrons does a Hydrogen atom have in its outer shell?
(7) Why does sharing electrons mean that the atoms are more stable as a molecule than as
single atoms?
(8) The two atoms are bonded, because they are more stable when they are close together.
Why must they remain close together?
(9) How many electrons are in the outer shell of a Chlorine atom?
(10)How many electrons are in the outer shell of a Hydrogen atom?
(11)Are the electrons from the Chlorine shown as dots or crosses?
TASK B
Draw dot and cross diagrams to show the covalent bonds in FOUR other molecules.
You could include: Water, Ammonia, Methane, Chlorine molecules, Carbon dioxide, Nitrogen
molecules, Oxygen molecules.
Extension question: What is special about the covalent bonds in Oxygen, Nitrogen and Carbon
dioxide?
TASK C