The periodic Table and the atom

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The periodic Table and the atom

• Lesson 3

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Elements and the Periodic Table

• Elements are pure substances that
  consist of atoms. The periodic table consists of
  over 100 elements all of which have a certain
  spot on the table.

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The periodic table of elements
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Important Features of the Table

• The elements are also organized in two fashions
  horizontal vertical and horizontal lines called
  groups and periods.
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• Groups- elements with similar chemical properties
  in a vertical column in the main part of the
  table
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• Period elements, arranged in a horizontal row,
  whose properties change from metallic on the left
  to non-metallic on the right

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Groups / families
Periods
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• Metals- Left side of the periodic
  table
• The majority of elements on the periodic table
  are metals . All metals, except for
  mercury are solids at room
  temperature. Metals have the following
  properties.
• Malleable The ability to be
  hammered or bent into a shape.
• Lustre They are shiny
  in appearance.
• Ductile They can be
  pulled into a wire.
• Conductor of electricity
  Electricity can travel through the metal.

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• Non-Metals- Right side of the
  periodic table
• Most of the remaining elements in the periodic
  table are non-metals .
• Non-metals generally have these properties
• Non-conductor
  of electricity in its solid form
• At room temperature most are
  gasses or solids
  .
• Solids are brittle and
  lack the lustre of metals

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• Metalloids- middle right of
  the periodic table
• Some elements do not fit as metals or non-metals.
  These fit on either side of the staircase that
  divides the metals and the non-metals. They have
  some properties of metals and some properties of
  non-metals.

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Group Names

• Alkali Metals This is the first
  group in the periodic table. They are soft
  , silver coloured, solids
  and at room temperature and react violently with
  water. They must be stored in oil to prevent them
  from reacting.

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Group Names

• Alkaline earth metals This is the
  second group in the periodic table.
  They are light, very reactive, solids
  at room temperature and all react
  with oxygen in the air.

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Group Names

• Transition metals Theses metals have a wide
  variety of properties and reactivates. They are
  generally hard , strong
  metals that conduct
  electricity

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Group Names

• Representative elements Groups 1,2 and 13-17.
  There are metals and
  non-metals. Some are solids while others are
  gases and there is one liquid .
  They follow the periodic law.

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Group Names

• Halogens Non-metals in group 17. They may be
  solids, liquids or gasses and are extremely
  reactive .

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Group Names

• Noble gasses They are gasses
  at room temperature. They have a low melting
  point and boiling point. They are also very
  un-reactive .

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Elements and Atomic Structure

• Atoms are composed of three subatomic particles
• Protons- Heavy positively charged particle found
  in the nucleus
• Neutrons -are neutral particles that have the
  same mass as protons and are located in the
  nucleus
• Electrons- Negatively charged particles with
  almost no mass. They circle the nucleus at
  different energy levels.
• The nucleus contains the protons and neutrons

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nucleus
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Atomic Number (Z)

• Atomic number - the number of protons in an atom
  of an element.
• Each element has a set number of protons and
  every atom from that element will have that many
  protons.
• The pattern for increasing protons moves from
  left to right and then down to the next row just
  like reading a book.

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Atomic Mass (A)

• Atomic mass - the average mass of an elements
  atoms.
• Total mass of protons and neutrons.
• Atomic mass is given in atomic mass units (amu).
• H has a mass of 1.01 amu. This means that iron
  atoms are about 55.85 times heavier than hydrogen
  atoms.
• Atomic masses are always expressed as decimal
  fractions. One reason that they do not have whole
  number values is that, except for fluorine, atoms
  of the same element have different numbers of
  neutrons.

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Atomic Mass (A)

• Example A hydrogen atom has one proton and one
  electron but no neutron. A small percentage of
  hydrogen atoms have 1 p, 1e, and 1n. 1 p, 1e,
  and 2n.
• Atomic mass generally increases in order of
  atomic number.
• Exception iodine (I) has a lower atomic mass
  than tellurium (Te).

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• Example
• Oxygen has an atomic number of 8 and a atomic
  mass of 16.00
• N A Z
• N 16.00 8 8 neutrons
• Work on the worksheet