Download Lesson 6 What are the subatomic particles of an atom

What are the subatomic
particles of an atom?
All pupils will be able to (Baseline): Recall what
atomic number represents.
Most pupils will be able to (Further): Describe the
structure of the atom and why atoms have no overall
charge.
Some pupils will be able to (Challenge): Describe
the trends in atomic radius down a group and across a
period.
Just how small is an atom?
Elements – different types of atom
Elements are the simplest substances. There are about 100 different elements.
Where can we find these elements?
Each element is made up of very tiny particles called atoms, and each element is made up
of just one particular type of atom, which is different to the atoms in any other element.
Gold is an element made up
of only gold atoms.
Carbon is an element made up
of only carbon atoms.
Atoms – the building blocks
John Dalton had the first ideas about the existence of atoms over 200 years ago.
However, it is only relatively recently that
special microscopes (called electron
microscopes) have been invented that can
actually ‘see’ atoms.
Electron microscopes produce images similar
to this one. What could it be showing?
The grey blobs are individual lead atoms.
How small is an atom?
Atoms are very small – they are about 0.00000001 cm wide.
Think about the thickness of a
crisp.
The number of atoms you
would need to stack up to make
the thickness of a crisp, is
approximately the same number
of crisps you would need to
stack up to make the height of
Mount Everest!
That’s roughly 7 million
crisps!
What particles are atoms made of?
For some time, people thought that atoms were the smallest particles and could
not be broken into anything smaller.
Scientists now know that atoms are actually made from even smaller particles.
There are three types:
proton
neutron
How are these particles arranged inside the atom?
electron
What is the structure of an atom?
Protons, neutrons and electrons are not evenly distributed in an atom.
The protons and neutrons exist in a
dense core at the centre of the atom.
This is called the nucleus.
The electrons are spread out
around the edge of the atom.
They orbit the nucleus in
layers called shells.
Labelling the atom
Atomic Number, Z
All atoms of the same element
have the same number of protons
in the nucleus, Z
13
Al
26.981
Atomic number
Atom symbol
AVERAGE Atomic Mass
Mass Number, A

C atom with 6 protons and 6 neutrons is the
mass standard
= 12 atomic mass units

Mass Number (A)

NOT on the periodic table…(it is the AVERAGE
atomic mass on the table)

A boron atom can have
= 5 p + 5 n = 10 amu

= # protons + # neutrons
A
10
Z
5
A
B
Counting Protons, Neutrons, and
Electrons

Protons = atomic number (small number
from periodic table)

Neutrons = mass number – no. of protons
(mass number is protons and neutrons
because the mass of electrons is negligible)

Electrons = proton number
◦ If it’s an atom, the protons and electrons must be the
SAME so that it is has a charge of zero, therefore
NEUTRAL (equal numbers of + and -)
Fill in the table in your books:
Protons have a Relative mass of 1
and a positive charge. They are
found in the nucleus.
Electrons have a Relative mass of 0
and a charge of -1. They are
found in the “shells” or “orbits”.
Neutrons have a Relative mass of 1
and no charge. They are
found in the nucleus.
Subatomic Particles
Subatomic
Particle
Relative
Charge
Relative Mass
Position in the
Atom
Proton
+1
1
Nucleus
Neutron
0
1
Nucleus
Electron
-1
Tiny, close to 0
Shells
The Periodic Table

Look at your periodic tables and draw
out an atom of:
◦ Lithium
◦ Sodium
◦ Fluorine
What do Li and Na have in common?
 What do F and Li have in common?
 Does this have anything to do with their
placement on the periodic table?

Plenary

Write down one thing about atoms you
are sure of, one thing you are unsure of
and one thing you need to know more
about.