Download Why are atoms of lead different to those of gold and why can we not

Aim:
What makes the atoms of
one element different to the
atoms of another element?
As much as we would like to, we cannot
turn lead into gold, but why can we not?
Why are atoms of lead different to those
of gold and why can we not just simply
change them?
To answer this we first of
all have to think about
what an atom is. Much
research was carried out
into this and in 1909 a
famous scientist Ernest
Rutherford first identified
the atom as we see it
today.
He took a very thin bit of gold foil
surrounded in photographic paper and
fired radioactive particles at it. The
photographic paper would change colour
when hit by radioactive particles.
His results showed that most of the gold
foil is space as the radioactive particles
went straight through the foil. This left
little cirles where the gold atoms were.
It was not until 1932 that we finally
established the structure of the atom.
Lets look at an atoms of helium.
Activity 5
Atoms contain three different particles
Electrons are negatively charged particles
that orbit a mass at the centre of the
atom.
The centre of the atom is known as the
nucleus. This contains positive proton
particles and neutral neutron particles.
Use this info to label activity 5.
Activity 5
This atomic structure is unique to helium.
Every element has its own atomic
structure.
The number of protons is equal to the
atomic number of an element so helium
has the atomic number 2.
You should also notice that in an atom the
number of positive protons is equal to the
number negative electrons. This ensures
the charges are balanced within the atom.
An atom of helium has a mass of 4 atomic
mass units. This is made up from the
protons plus the number neutrons.
Every proton and neutron has a mass of 1
atomic mass unit (amu)
Electrons are so small we do not count
their mass.
Use the information in the book to
complete the table
Particle
Charge
Relative Atomic
Mass (amu)
Location in
the Atom
0
Orbits
nucleus
Nucleus
Positive
1
Atomic mass units (amu) are special units
we use to measure the mass of particles
on an atomic scale.
Activity 7a – Making an atom
In your group you will be given a supply of
string and some beads. Using this
equipment you have to show the structure
of an atom of a given element.
Activity 7b – Making an atom
Using the instruction card, complete
activity 7 to make an atom
Once everyone is finished go round and
have a look at the atoms. Copy and
complete the following table:
Element How I Identified the Element
The Periodic Table can tell us a lot of
information.
The atomic number tells us the number of
protons and therefore the number of
electrons as they have to be equal in
atoms.
We can also use the data book to find
the relative atomic mass of an element.
We have a special notation for this
information; here is this information for
helium;
Copy this into your notes
Using your data book give information on
lithium’s atomic number and mass like the
example of helium on the previous page.
Activity 8
Copy and use your data book to complete
the table below;
Element Atomic Number Number Number Mass
Name Number Protons Electrons Neutrons (amu)
1
6
16
19
10
Stuck? Ask your teacher for the help sheet
How are the atoms of the same element
similar?
The atom has two main parts, the nucleus
and the electrons, explain why the nucleus
has a positive charge.
Why does an atom not have an overall
charge?
How are the atoms of the same element
similar?
Atoms of the same element contain the
same number of protons and electrons
The atom has two main parts, the nucleus
and the electrons, explain why the nucleus
has a positive charge.
The nucleus has a positive charge as it
contains positive protons and neutral
neutrons leaving it neutral overall
Why does an atom not have an overall
charge?
The number of positive protons in an atom
are equal to the number of negative
electrons leaving the atom with no overall
charge
Homework 1