30S Chemistry

1
30S Chemistry

• Unit 2 Nomenclature and Bonding
• Chapter 2

2
Review of Unit 1

• Give the electron configurations, electron
  filling diagram and Lewis dot structure for the
  following elements
• Sodium
• Copper
• Bromine
• Nitrogen
• Iron
• Calcium

3
Basics of Bonding

• Terms to know
• Atom smallest particle that makes up matter.
• Element pure substance made up of one type of
  atom
• Molecule pure substance made up of 2 or more
  atoms bonded together covalently
• eg. H2O - water
• Compound pure substance made up of 2 or more
  ions, which are bonded together by the
  electrostatic attraction between the positive and
  negative charges.
• eg. NaCl - sodium chloride
• Fe2O3 - iron (III) oxide

4
Basics of Bonding

• It is a chemical process, meaning the
  characteristics of a substance change to form the
  new substance.
• Electrons are lost, gained or shared to form the
  new substance.
• A bond is a force between two objects
  (Intramolecular Force). When bonds form, energy
  is needed and when the bonds break energy is
  released.

5
Basics of Bonding

• Atoms bond according to the Law of constant
  composition (Dalton)
• Bonding only takes place in the valence orbital
  only. The inner electrons and the nucleus just
  sit there.

6
Basics of Bonding

• Bonding occurs in two ways
• Electrons can move from one atom to another, by
  gaining or losing electrons. This is called an
  IONIC Bond.
• Electrons can be shared between atoms. This is
  called a COVALENT Bond.
• IONIC metal and non-metal or () and a (-)
• COVALENT 2 or more non-metals

7
Basics of Bonding

• The basis behind bonding
• All atoms want to lose / gain / share electrons
  to complete their outer orbital to become
  isoelectric with a Noble Gas. (ie. To have the
  same amount of valence electrons as Group 8)
  This is also known as the Octet Rule.
• Why?

Noble Gases are the most stable of all the
elements and non-reactive. By becoming like a
noble gas, the structure becomes stable as well.
8
Basics of Bonding

• Chemical Formulas
• Consist of the symbols for the combined elements
  and the ratio of the atoms combined

9
Basics of Bonding

• Names of Compounds and Molecules
• We use the IUPAC name. (International Union of
  Pure and Applied Chemistry)
• Some have common names , as well, that we use
  every day.

10
Basics of Bonding

• Types of Compounds and Molecules
• Binary composed of 2 elements, names end in
  ide
• Ternary composed of 3 or more elements, ending
  of the names vary, many are Polyatomic Ions and
  large covalent molecules

11
Ionic Bonding

• Bond between two oppositely charged ions which
  forms when the two are attracted to one another
  by an electrostatic force.
• An ionic bond is a type of chemical bond that
  involves a metal and a non-metal (or polyatomic
  ion such as nitrate) through an electrostatic
  attraction.
• Ion charged particle which started out neutral
  but lost or gained electrons

12
Ionic Bonding

• Rules of thumb
• metals lose electrons and form ions
• non-metals gain electrons and form ions
• the sum of the ions in the compound will 0, as
  the compound is electrically neutral

13
Ionic Bonding

• The metal donates one or more electrons, forming
  a positively charged ion or cation with a stable
  electron configuration.
• These electrons then enter the non metal, causing
  it to form a negatively charged ion or anion
  which also has a stable electron configuration.
• The electrostatic attraction between the
  oppositely charged ions causes them to come
  together and form a bond.

14
Ionic Bonding

• The removal of electrons from the atoms is
  endothermic and causes the ions to have a higher
  energy.
• There may also be energy changes associated with
  breaking of existing bonds or the addition of
  more than one electron to form anions.
• However, the attraction of the ions to each other
  lowers their energy.

15
Ionic Bonding

• Ionic bonding will occur only if the overall
  energy change for the reaction is favourable
  when the bonded atoms have a lower energy than
  the free ones.
• The larger the resulting energy change the
  stronger the bond. The low electronegativity of
  metals and high electronegativity of non-metals
  means that the energy change of the reaction is
  most favorable when metals lose electrons and
  non-metals gain electrons. (Ionization Energy)

16
Ionic Bonding

• Pure ionic bonding is not known to exist.
• All ionic compounds have a degree of covalent
  bonding.
• The larger the difference in electronegativity
  between two atoms, the more ionic the bond.
• Ionic compounds conduct electricity when molten
  or in solution. They generally have a high
  melting point and many tend to be soluble in
  water.

17
Ionic Bonding

• Formation of Ions
• Remember
• You are losing or gaining negative particles
• Losing electrons more positive
• More protons than electrons
• Gaining electrons more negative
• More electrons than protons

18
Ionic Bonding

• Formation of Ionic Compounds
• Identify the elements as metals or non-metals, or
  identify and charges
• Find the charges for the ions, using the Periodic
  Table from Bohr Models or valence electrons
• Balance the charges between ions or number of
  electrons being lost or gained. Remember the sum
  of the ions 0!!
• Write the formula using subscripts for how many
  of each ion are used.
• Give the name of the compound, in the order of
  ion and ion. For binary substances, the
  negative ion name is the name of the element, but
  you drop the ending and add ide to the end.
  For polyatomic ions, it is the name of the ion
  itself.

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Ionic Bonding

• Ionic Bonding Polyatomic Ions (Ions, so
  therefore, IONIC BONDING)
• poly many
• atomic made of atoms
• Polyatomic atoms are formed from the breakdown
  and reactions of acids and bases. The reaction
  will leave the ion to bond with something else.

MANY ATOM ION
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Ionic Bonding

• The process of creating a formula, is the same as
  all ionic bonds and structures. Balance charges
  0, using a subscript to denote the number of
  ions needed. The difference is brackets are used
  for polyatomic ions, if more than one are used.
• Naming is very simple. The name of the cation,
  followed by the name of the anion.

21
Ionic Bonding

• Transition Metals (LOSE e-, so always cations
  formed, and ions, therefore IONIC BONDING!!)
• Transition metals are so called, because they can
  form more than one form of positive ion. (Move e-
  from d level to sp or s to d, to create a more
  stable arrangement, changing the number of
  valence e-) Reference Atomic Structure Unit
• Since there are multiple ions, the charges need
  to be distinguished for the structures.
• Roman numerals correspond to the charge on the
  metallic ion.

22
Ionic Bonding

• The Properties of Ionic Compounds
• Read p. 69 71
• Taking notes
• What are the properties of Ionic compounds?
  Explain the reasons behind their properties.
• What main ideas determine the formation of Ionic
  compounds?
• How do we predict the ions of atoms?
• What ions are essential in the human body?
• Read p. 72 73
• Review how we represent Ionic Bonds, using Lewis
  Dot Structures

23
Covalent Bonding (p. 75 79)

• When the conditions for electron transfer are
  unfavourable, a different kind of bonding can
  occur between atoms.
• This second type of chemical bonding is called
  covalent bonding
• Covalent Bonding - electrons being shared by
  atoms rather than being transferred from one atom
  to another. In general, usually between two
  non-metals

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Covalent Bonding

• The driving force behind the formation of a
  covalent bond is still the desire of the atoms
  concerned to obtain a stable electron
  configuration, usually a full valence shell.
• In covalent compounds, this is achieved by the
  sharing of two or more electrons the shared
  electrons are then considered as simultaneously
  belonging to the valence shells of both of the
  atoms involved.

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Covalent Bonding

• Electrons are shared since the electronegativity
  differences between the bonded atoms is small.
• Unlike ionic compounds, covalent molecules exist
  as true molecules. 
• Because electrons are shared in covalent
  molecules, no full ionic charges are formed. 
• Thus covalent molecules are not strongly
  attracted to one another.  As a result, covalent
  molecules move about freely and tend to exist as
  liquids or gases at room temperature.  

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Covalent Bonding

• Formation of Covalent Molecules and Naming (p. 97
  98)
• Identify the elements as metals or non-metals.
• Find the number of valence electrons using the
  Periodic Table from Bohr Models, Lewis Dot
  structures, noting valence electrons
• Create bonds by pairing up single electrons.
  Bonds can be single, double or triple, depending
  on the number of valence electrons used

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Covalent Bonding

• All atoms need a full octet
• Write the formula using subscripts for how many
  of each atom are used.
• Give the name/formula of the molecule, by
• Taking the name of the atom that appears furthest
  on the left of the periodic table and then the
  next.

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Covalent Bonding

• Some rules
• Hydrogen is in Gr. 1 because it has one valence
  electron. It sits between Gr. 5 and 6.
  Therefore, with Gr. 3, 4 and 5, it is the second
  element in the formula, and for Gr. 6 and 7, it
  is the first element
• Atoms lower down the periodic table (Periods 3,
  etc.) are the first element in the name. (Unless
  you are following rule 1)

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Covalent Bonding

• For the second atom in the formula, if it is
  binary, drop the ending and add ide. For
  larger molecules, such as large organic
  molecules, there are special names.
• For the name, because there are no charges,
  multiple structures can form. Therefore, to
  differentiate between molecules, prefixes are
  used.

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Covalent Bonding

• Properties of Molecules (p. 80)
• Read p. 80 Take notes on the Properties of
  Molecules

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Representing Molecules and Compounds Lewis Dot
Structures

• Drawing the structures is important because it
  will allow us to see the structure and determine
  its shape.
• If we know its shape, we can determine polarity,
  how the structure reacts, and its physical
  properties as well.

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Representing Molecules and Compounds Lewis Dot
Structures

• Drawing Lewis Dot Structures
• Draw skeletal structure of compound showing what
  atoms are bonded to each other. We move the
  valence electrons to their bonding positions.
• Example Carbon, Nitrogen
• If it is an ionic substance, show the ions and
  charges.

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Representing Molecules and Compounds Lewis Dot
Structures

• If it is a covalent molecule
• Put least electronegative element in the center.
• Count total number of valence e-. Add 1 for each
  negative charge. Subtract 1 for each positive
  charge.
• Complete an octet for all atoms except hydrogen.
• If structure contains too many electrons, form
  double and triple bonds on central atom as needed.

34
Naming Acids and Bases (p. 98 100)

• Acids
• Sour
• Electroytes
• Gritty feel
• pH 0 - 6.9
• Blue litmus red
• React with bases to form a salt and water
• Put H into solution
• Made by reaction of oxides and water and binary
  covalent molecules and water

• Bases
• Bitter
• Electrolytes
• Slippery feel
• pH 7.1 14
• Red litmus blue
• React with acids to form a salt and water
• Put OH- into solution
• Made by metallic oxides and water

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Naming Acids and Bases (p. 98 100)

• Acids
• Contains one or more hydrogen atoms
• General formula HnX
• H hydrogen atom
• n number of hydrogen atoms (subscript)
• X monoatomic or polyatomic anion

36
Naming Acids and Bases (p. 98 100)

• When the name of the anion ends in ide (X), the
  acid is a binary acid, and the prefix is hydro
  and the ending is ic
• When there is a polyatomic ion, that makes up
  (X), the acid is a ternary acid. If the ion ends
  in ite, the ending for the acid is ous
• When the polyatomic ion ends in ate, the ending
  for the acid is ic

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Naming Acids and Bases (p. 98 100)

• Hint If the name of the anion is ate, and the
  acid is ic, one less oxygen, the acid is ous,
  one more less oxygen, the acid is prefix hypo
  and ending is ous
• If there is one more oxygen than the ate
  polyatomic ion, the name is, prefix per and
  ending ic
• Some organic acids, you just have to memorize the
  name. Ex. Ethanoic Acid CH3COOH

38
Naming Acids and Bases (p. 98 100)

• Bases
• Named the same as ionic compounds
• Some you just have to memorize (ie. Ammonia)

39
Hydrates (p. 95 96)

• Hydrate a tertiary ionic compound, in which the
  crystal structure contains water.
• When the crystal structure contains water, it is
  called hydrated.
• When heat is applied to the crystal, water will
  be released in the form of water vapour. This is
  called an anhydrous structure (anhydrate)