Chemistry Background - KEY
1. Six main elements make up about 98% of your
body. Using the acronym CHNOPS, write out the
name of these six main elements.
C – Carbon
H – Hydrogen
N – Nitrogen
O – Oxygen
P – Phosphorous
S - Sulfur
2. Copy out and label both figure 2.2 and table 2.1.
Subatomic Particles:
NAME
CHARGE
MASS
ELECTRON
One Negative
PROTON
One Positive One Atomic Mass Unit
NEUTRON
No Charge
Almost No Mass
One Atomic Mass Unit
3. What is an “electrically neutral” atom?
The number of protons equals the number of
electrons. Example : Carbon  6 e- and 6 +
4. All elements listed under Roman Numeral VI –
Group, share what common characteristic?
They all have 6 electrons in their outermost shell.
5. What is the difference between, C12, C13 and
C14?
They are ISOTOPES of carbon.
C12 – Carbon 12  has 6 + and 6 neutrons.
C13 – Carbon 13  has 6 + and 7 neutrons
C14 – Carbon 14  has 6 + and 8 neutrons.
6. Describe three uses of radioactive isotopes in
science.
a) They can be used medically as tracers for
showing contrast in diagnostic imaging. Ex. Bone
scans, Thyroid gland tests etc. And in studying
metabolic pathway reactions.
b) Radiation given off to create PET Scan images.
c) Radioactive beads can be implanted in the body
to emit radiation to kill cancerous cells.
7. Try to recall from Chem. 11, what the “Octet
Rule” states. (Hint p. 23)
Atoms are most stable when they possess 8
electrons in their outer shell.
8. Why do Sodium and Chlorine like to form an
ionic bond between each other?
Sodium (Na) has 1 electron in its outer shell, while
Chlorine (Cl) has 7 electrons in its outer shell.
Chlorine would like to gain one more to get up to
8  Cl -; while Sodium would like to donate one
to get back to its lower fully occupied shell Na+
9. The elements of the Periodic Table can be
grouped as being either metals, semimetals, or
non-metals; between which groups will ionic
bonding take place?
Between Metals and Non-metals.
10. What happens to the electron arrangements
when two atoms of nitrogen combine? (Note –
Octet Rule)
Each nitrogen atom has 5 electrons in its outer
shell, so each would like to have 8. They satisfy
the octet rule by sharing three pairs of electrons.
11. What type of bonding takes place when nonmetals join with other non-metals?
COVALENT
12. Draw figure 2.6-C to illustrate the covalent
bond formed between oxygen and hydrogen to
make a molecule of H2O.