Writing and Naming Compounds

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Writing and Naming Compounds
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ALL METALS have several characteristics

• have luster (shiny) some have more luster than
  others, but all metals have some shine. All
  metals are silvery or gray colored except gold
  and copper.
• Will conduct electricity some conduct better
  than others but all metals will conduct
  electricity to some degree gold is considered to
  be the best electrical conductor, also silver,
  copper and aluminum
• Ductile can be pulled out into a wire
• Malleable - can be hammered into a thin sheet
  some are more malleable than others gold is
  probably the most malleable, followed by silver
  and copper.
• ALWAYS LOSE ELECRONS FROM THEIR OUTER ENERGY
  LEVEL TO FORM POSITIVE IONS WHIH ARE CALLED
  CATIONS. Since the positively-charged ion will
  be attracted to the negative electrode (opposites
  attract), the ion attracted to the cathode is
  called the CATION.
• The Roman numeral at the top of the column on
  the Periodic Chart is the number of electrons in
  its outermost energy level, and these are the
  electrons which the metal will lose (all of them)

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ALL NON-METALS have opposite characteristics

• do not have luster and are frequently powdery,
  liquid or gaseous most are colored
• do not conduct electricity (non-conductors)
  except some of the metalloids which are used in
  computer chips
• are not ductile
• are not malleable
• ALWAYS GAIN ELECTRONS INTO THEIR OUTER ENERGY
  LEVEL UNTIL THEY HAVE 8 AND FORM NEGATIVE IONS
  WHICH ARE CALLED ANIONS. Since a
  negatively-charged particle will be attracted to
  the positive electrode (opposites attract), the
  ion which is attracted to the anode is called the
  ANION (opposites attract), the ion which is
  attracted to the anode is called the ANION.
• The Roman numeral at the top of the column on the
  Periodic Chart is the number of electrons in that
  atoms outermost energy level, and non-metals must
  gain enough electrons here to make a total of 8
  in the outermost energy level.

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• Positive ions (CATIONS) have more protons than
  they have electrons since metals ALWAYS LOSE
  electrons. This results in the ion having a
  positive charge.
• Negative ions (ANIONS) have gained electrons in
  their outermost energy levels and therefore have
  more electrons than protons. This results in the
  ion having a negative charge.

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OXIDATION NUMBER

• is the overall charge on an ion after it has lost
  electrons (metals) or gained electrons
  (non-metals). Oxidation numbers can be
  determined by looking at the Periodic Chart for
  the A column elements, but usually it is easier
  just to memorize the oxidation number associated
  with every ion rather than having to look it up
  every time.
• When ions are combined together to form
  compounds, THE OVERALL CHARGE OF THE COMPOUND
  WHICH RESULTS MUST BE ZERO OR NEUTRAL.

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For example

• if an ion of potassium (whose charge is 1)
  combined with an ion of chlorine (whose charge is
  -1), the compound that results is electrically
  neutral as written in a 11 ratio of ions i.e. 1
  potassium ion with a charge of 1 will exactly
  neutralize 1 chlorine ion with a charge of -1, so
  the formula for the compound is written simply
• KCl (1 K to 1 Cl)

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However,

• if an ion of magnesium (whose charge is 2
  combined wit an ion of chlorine (whose charge is
  -1), the compound that forms must be electrically
  neutral, so therefore, it takes 2 of the chlorine
  ions (with a charge of -1 each) to neutralize 1
  of the magnesium ions whose charge is 2.
• When we write the number which shows us that
  there must be more than 1 of a particular ion
  present to make the compound neutral is always
  written as a SUBSCRIPT.

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NOTICE THAT IN WRITING CHEMICAL FORMULAS, THE
METAL ION IS ALWAYS WRITTEN FIRST AND THE
NON-METAL ION IS WRITTEN LAST.
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Write a correct formula for the compound, which
would form between. (Criss Cross Method)

• lithium and fluorine
• calcium and sulfur
• cesium and oxygen
• aluminum and oxygen
• sodium and sulfur
• aluminum and chlorine
• potassium an oxygen

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We will basically be writing and naming two
different types of compoundsionic and molecular,
ionic compounds are those compounds which are
made up of

• a metal and a non-metal
• a metal and a polyatomic ion
• ammonium ion and a non-metal
• ammonium ion and a polyatomic ion

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When naming BINARY (2 elements only) ionic
compounds (i.e. a metal and a non-metal)

• Call the entire name of the metal
• Shorten the name of the non-metal (usually at the
  2nd vowel from the end of the word) and
• Add the suffix ide
• Therefore KCl would be called potassium chloride,
  NOT potassium chlorine.

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Name the following binary ionic compounds

• MgBr2
• NaF
• Al2O3
• CdO
• ZnS
• Na2O
• K3N

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Some metals have more than one oxidation number
and when you name them you must indicate which of
the oxidation numbers you are using.

• There are only 5 elements which you need to
  memorize which have more than one oxidation
  number and they are
• Iron (3 or 2)
• Lead (4 or 2)
• Tin (4 or 2)
• Mercury (2 or 1)
• Copper (2 or 1)

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• some metals were found to have more than 2
  oxidation numbers, so we adopted a new system of
  naming called the IUPAC (international union of
  Pure and Applied Chemists) which uses the element
  name and a Roman numeral (in parenthesis) written
  after the name. So, we can also name the
  compounds copper (1) and copper (II), iron (III)
  and iron (II), lead (IV) and lead (II), tin (IV)
  and tin (II), and mercury (II) and mercury (I)

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Write correct formulas for the following

• tin (IV) chloride
• iron (III) oxide

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Covalent Compounds

• Compounds can also be written which consist of
  TWO __NON METALS. In this case, one of the
  non-metals must assume a positive oxidation
  number. You do not need to worry about which of
  the non-metals is more likely to assume the
  positive oxidation numberyou just need to be
  able to recognize that they are special
  compounds and therefore are named in a special
  way.
• When two non-metals combine to form a compound,
  it is called a _MOLECULAR COMPOUND (Covalent).

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Naming Covalent Compounds

• To name molecular compounds, we use a series of
  prefixes to indicate the NUBER OF ATOMS OF EACH
  ELEMENT WHICH ARE PRESENT. These prefixed are
  not used at any other time in naming. They are
• 1 mono - only used in naming the second
  element
• 2 di
• 3 tri
• 4 tetra
• 5 penta
• 6- hexa
• 7 hepta
• 8- octa
• 9 nona
• 10 deca

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NAMING

• If you wish to name Cl2O7 a molecular compound
  since it contains two non-metals, use the prefix
  to indicate how many chlorines are present and
  use the ENTIRE first elements name (not
  shortened nor modified) dichlorine. Then use a
  prefix to indicate how many atoms of the second
  element are present and shorten its name at the
  second vowel from the end of the name and add
  ide - heptaoxide.

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Naming Compounds

• Example name the following molecular compounds
• CO2
• N2O3
• Cl2O
• SO3
• CO