CHEMICAL PATTERNS

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CHEMICAL PATTERNS

• Module 3

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By the end of this lesson I should be able to..

• Predict the electron arrangement in atoms using
  the periodic table.
• Appreciate that atoms like to have full orbits of
  electrons if they are to be stable.
• Understand the link between electron arrangement
  and reactivity.
• Know which elements are the halogens.
• Know the properties of the halogens

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Using Power Point

• If it is written in white it should be in my
  exercise book!
• If it is written in red it need not be in my
  exercise book.

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The Atom
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The Atom
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Arranging electrons
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Arranging electrons
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Arranging electrons
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Arranging electrons
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Arranging electrons
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Arranging electrons
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Groups in the Periodic Table

• Elements in the same group always have the same
  number of electrons in their outer orbitals.
• All members of Group 1, the Alkali Metals, have 1
  electron in their outer shell.

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Groups in the Periodic Table

• All members of Group 2 have 2 electrons in their
  outer shell.
• All members of Group 7, the halogens, have 7
  electrons in their outer shell.

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Groups in the Periodic Table

• All members of Group 8, the Noble Gases, have 8
  electrons in their outer shell.

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Stable (happy) atoms!

• Atoms will always try and get full outer shells
  of electrons.
• If the outer shell is full the atom is stable!
• Atoms will always try and react in order to end
  up with a full outer shell!

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• Group 1 metals will react in order to lose their
  outer electron.
• This means they will have a positive charge after
  they have reacted.
• Because the lose one negative charge they are
  left positive overall.

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• Group 7 halogens will react in order to gain an
  extra outer electron.
• This means they will have a negative charge after
  they have reacted.
• Because the gain one negative charge they are
  left negative overall.

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Move into room 143!

• Looking at the HALOGENS!

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The Halogens
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Fluorine

• A very pale yellow gas
• Incredibly corrosive it can not be kept in a
  glass jar because it would rot the glass.
• These containers of fluorine are made of quartz.

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The Halogens
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The Halogens
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Chlorine

• A green gas
• Very poisonous
• Used in the First World War in the gas attacks
  that blinded and killed thousands of soldiers
  (used by both the Germans and the British)

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The Halogens
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The Halogens
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Bromine

• A brown liquid
• Will boil and turn into a gas with very little
  heating.
• Very poisonous can dissolve your lungs.
• Said to be put in the tea of troops to supress
  sexual desires!

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The Halogens
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The Halogens
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Iodine

• A dark purple solid.
• A strange substance which turns from a solid to a
  gas when heated without first turning into a
  liquid.
• Used in antiseptic to kill bacteria.

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The Halogens
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The Halogens
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Astatine

• A black solid.
• Very dangerous and usually radioactive.
• There is less than 30g in the entire Earth at any
  one time!
• Has no use what-so-ever!

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The Halogens
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The Halogens

• Fluorine
• Chlorine
• Bromine
• Iodine

most reactive
least reactive
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The Halogens

• Fluorine
• Chlorine
• Bromine
• Iodine

most reactive
least reactive

• all have 7 electrons in their outer shell
• all react to pick up an extra electron so that
  they have full outer shell and are stable!

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200 160 120 80 40 0 -40 -80 -120 -160 -200
I
Boiling point OC
Br
0 5 10 15 20 25 30 35 40 45
50 55 60 65 70 75 80
Atomic number
Cl
Fl
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200 160 120 80 40 0 -40 -80 -120 -160 -200
I
Boiling point OC
Br
0 5 10 15 20 25 30 35 40 45
50 55 60 65 70 75 80
Atomic number
Cl
Fl
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Graph showing the boiling point of the halogens
200 160 120 80 40 0 -40 -80 -120 -160 -200
I
Boiling point OC
Br
0 5 10 15 20 25 30 35 40 45
50 55 60 65 70 75 80
Atomic number
Cl
Fl