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  • 1 of 24 Boardworks Ltd 2016

    Atoms and Subatomic Particles

  • 2 of 24 Boardworks Ltd 2016

    Atoms and Subatomic Particles

  • 3 of 24 Boardworks Ltd 2016

    What are atoms made of?

    What is the size of one atom in nanometres (nm)?

  • 4 of 24 Boardworks Ltd 2016

    What particles are atoms made of?

    protons neutrons electrons

    Atoms are made up of three smaller, or subatomic, particles:

    The electrons are spread out

    around the edge of the atom.

    They orbit the nucleus in layers

    called shells (energy levels).

    The protons and neutrons exist in a

    dense core at the centre of the atom.

    This is called the nucleus. The radius of a nucleus is less

    than 1/10,000 of that of the atom.

  • 5 of 24 Boardworks Ltd 2016

    particle relative mass relative chargeproton

    neutron

    electron

    There are two properties of protons, neutrons

    and electrons that are especially important:

    relative mass

    relative electrical charge.

    The atoms of an element contain equal numbers of protons and electrons and so have no overall charge.

    -1almost 0

    01

    +11

    Mass and electrical charge

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    Properties of subatomic particles

  • 7 of 24 Boardworks Ltd 2016

    Discovering atomic structure

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    Summary: atomic structure

    The nucleus is:

    made up of protons and neutrons

    positively charged because of the

    protons

    dense because it contains most of the

    mass of the atom in a tiny space.

    Electrons are:

    very small and light, and negatively charged

    able to be lost or gained in chemical reactions

    found thinly spread around the outside of the nucleus,

    orbiting in layers called shells (energy levels).

  • 9 of 24 Boardworks Ltd 2016

    Atoms and Subatomic Particles

  • 10 of 24 Boardworks Ltd 2016

    How many protons?

    Each element has a definite and fixed number of protons.

    The atoms of any particular element always contain the

    same number of protons. For example:

    The number of protons in an atom is known as the atomic number or proton number.

    It is the smaller of the two numbers shown in most periodic tables.

    hydrogen atoms always contain 1 proton

    carbon atoms always contain 6 protons.

    If the number of protons changes, then the atom becomes

    a different element.

  • 11 of 24 Boardworks Ltd 2016

    sodium

    iron

    tin

    fluorine

    The atomic number (proton number)

    What are the atomic (proton) numbers of these elements?

    11

    26

    50

    9

  • 12 of 24 Boardworks Ltd 2016

    What is mass number?

    Electrons have a mass of almost zero, which means that the

    mass of each atom results almost entirely from the number

    of protons and neutrons in the nucleus.

    The sum of the protons and neutrons in an atoms nucleus is the mass number.

    1413aluminium

    43lithium

    01hydrogen

    neutronsprotonsatoms mass number

    27

    71

    It is the larger of the two numbers shown

    in most periodic tables.

  • 13 of 24 Boardworks Ltd 2016

    mass number = number of protons + number of neutrons

    What is the mass number?

    What is the mass number of these atoms?

    3227

    3529

    22

    59

    64

    4

    cobalt

    copper

    helium

    neutronsprotonsatoms mass number

    iodine

    germanium

    53

    32

    74

    41 73

    127

  • 14 of 24 Boardworks Ltd 2016

    Building a nucleus

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    What are the missing numbers?

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    Sodium (Na) can form an Na+ ion.

    11 protons

    12 neutrons

    10 electrons

    Na+ has a charge of +1 because it has lost one electron,

    and has one more proton than electrons.

    How many protons, electrons and neutrons does Na+ have?

    Use the tile from the periodic table below to help you.

    Charged particles: ions

  • 17 of 24 Boardworks Ltd 2016

    Atoms and Subatomic Particles

  • 18 of 24 Boardworks Ltd 2016

    Introduction to electron shells

    A Danish scientist called Niels Bohr suggested that electrons

    orbit the nucleus in fixed energy levels called shells.

    The arrangement

    of electrons can be

    written from the

    lowest energy level

    to the highest.

    1st shell holdsa maximum of

    2 electrons

    2nd shell holdsa maximum of

    8 electrons

    3rd shell holdsa maximum of

    8 electrons

    Each shell has a maximum number of electrons that it is able

    to hold. Electrons fill the shells nearest the nucleus first.

    This electron arrangement of this atom is written as 2,8,8.

  • 19 of 24 Boardworks Ltd 2016

    How are electrons arranged?

  • 20 of 24 Boardworks Ltd 2016

    Calculating electron arrangement

  • 21 of 24 Boardworks Ltd 2016

    Atoms and Subatomic Particles

  • 22 of 24 Boardworks Ltd 2016

    Glossary

  • 23 of 24 Boardworks Ltd 2016

    True or false?

  • 24 of 24 Boardworks Ltd 2016

    Multiple-choice quiz

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