science for preparatory section in national curriculum the atom.pdf

The atom and its features

1. INTRODUCTION TO THE ATOM:
WHAT IS AN ATOM?

EVERYTHING AROUND US IS
MADE OF ATOMS, FROM THE AIR
WE BREATHE TO THE OBJECTS WE USE EVERY DAY.
An atom is
the basic unit
of matter
.

2. Size of an Atom:
Atoms are incredibly
small. You can't see
them with your eyes
or even with most
microscopes.
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3. STRUCTURE OF THE ATOM:
Nucleus:
At the center of the atom
is the nucleus.
The nucleus is made up
of two types of particles:
Protons: These have a positive charge (+).
Neutrons: These have no charge (neutral).

4. STRUCTURE OF THE ATOM:
Electrons are tiny particles
that orbit
ELECTRONS:

the nucleus.
They have a negative
charge (-).
Electrons move very quickly around the
nucleus in what we call "energy levels ".
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5. RELATIVE ELECTRIC CHARGE OF
THE COMPONENTS OF THE ATOM
PROTONS
POSITIVE
CHARGE
(+)
NEUTRONS
NO
CHARGE
(NEUTRAL)
ELECTRONS:
NEGATIVE
CHARGE
(-).
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6. THE NUCLEUS OF AN ATOM IS
POSITIVELY CHARGED.
Because Protons are positively charged and
neutrons have no charge.
The charge of a proton is equal to the
charge of an electron in magnitude but
different in kind.
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7. Protons:
Mass: Approximately 1 atomic mass unit (amu).
Neutrons:
Mass: Also about 1 amu, almost identical to that of protons.
Electrons:
Mass: About 1/1836 of an amu (extremely small compared to
protons and neutrons).
Although electrons have mass, it is so small that it is often
considered negligible when calculating the total mass of an atom.
Comparing the Mass of Atomic Components
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8. THE MASS OF A PROTON

THE MASS OF A NEUTRON.
The nucleus is where almost all of the atom's
mass is concentrated
because protons and neutrons are much
heavier than electrons.
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