Download Activity 17 Follow-up

Major Concepts
Isotope Activity
•An element can have a different number of
neutrons, but always has the same number
of protons
•The atomic weight is the average weight of
all the known isotopes of the element
•The element which appears on the periodic
table is the isotope which is most abundant
Major Concepts cont.
Atomic Symbol
mass number
23
atomic number
11
Na
sodium-23
• Elements of the same atom have the same
atomic number, but different mass numbers
Activity 17 Analysis
3. Was it possible for an atom to make more
than one bond? Explain, and give an
example.
•
•
All atoms except hydrogen can make more
than one bond
For example…….
4. How many bonds could each of the
following make with hydrogen?
a.
b.
c.
d.
Si (Atomic # 14)
S (Atomic # 34)
I (Atomic # 53)
As (Atomic # 33)
4
2
1
3
5. If you had two oxygen atoms and one
hydrogen atom, could you form a molecule?
Explain.
•
•
•
•
No
With 2 oxygens bonded together, you could
bond 1 hydrogen.
One of the oxygen atoms would have an
unbonded site.
It is not possible to put them together with all
sites bonded
H
Unbonded site
O
O
6. Make a drawing of the models to show the
difference between an atom and a molecule.
H
H
Atom
O
Molecule
•
•
•
a molecule is made of more than one atom.
it can be the same atom or it can be
composed of more than one kind of atom.
example of each…….
Name _______________ Period ____ Date _______
Activity 17, Analysis # 6 & Activity 16, Analysis #4
Demo: Sodium in Water
Chemical Formula
2Na(s) + 2H2O(l) ------ 2NaOH(aq) + H2(g)
Sodium and hydrogen are both in group 1 and are
very reactive. When the sodium reacts with the
water it takes the place of one of the hydrogen
atoms. This happens because sodium is more
reactive than the hydrogen it is replacing.
Reactivity is largely due to the atomic radius of an
element and the valence. Larger metals lose their
outer electrons more easily. If the sodium was less
reactive than the hydrogen then there probably
would be no chemical reaction in this case.