Chemistry C2

• State the types of chemical bonds

  Ionic, covalent, metallic
• How do ionic bonds join particles?

  oppositely charged ions strongly attracted to one another by electrostatic forces

  
• How do covalent bonds join particles?

  Share pairs of electrons, held together by strong electrostatic forces of attraction between oppositely charged ions

  
• How do metallic bonds join particles?

  Strong forces of electrostatic attraction between the positive metal ions and shared negative electrons

  
• Ionic bonding occurs between...

  metals and non-metals
• Covalent bonding occurs between...

  non-metals
• Metallic bonding occurs between...

  metals/alloys
• What happens to atoms involved when ionic bonds are formed

  Electrons from the outer shell of the metal atom are transferred to the non metal atom
• metals ____ electrons to become ________ charged ions

  lose, positively
• non-metals ____ electrons to become ________ charged ions

  gains, negatively
• What is the structure of sodium chloride?

  Giant ionic lattice

  
• What can be the limitations of using dot and cross diagrams?

  -Don't show structure of compound, one dimensional

  -Size of the ions

  -How they're arranged
• How are metals arranged?

  Metals have a giant regular structure of positive ions surrounded by a sea of delocalised electrons
• Why are metallic bongs strong?

  Electrons in the outer shell of the atoms are delocalised. Strong forces of electrostatic attraction between positive metal atoms and the electrons
• What are the three states of matter?

  solid, liquid, gas
• What changes of state occur at the melting point?

  Melting and freezing
• What changes of state occur at the boiling point?

  boiling and condensing
• Represent the three states of matter using simple particle model

  
• Use particle theory to explain melting and boiling

  substance is heated, it gains kinetic energy so it vibrates more. At a certain temperature, particles have enough energy to break free from their positions

  melting- solid turns liquid

  boiling- liquid turns gas
• Use particle theory to explain condensing and freezing

  Gas cools, particles no longer have enough energy to overcome forces of attraction so bonds form. Until the boiling point, so many bonds formed that gas becomes liquid- condensing. At the melting point, there is no more energy to form more bonds but there are even more so they're held in place. Liquid becomes solid- freezing.
• What does the amount of energy needed for a substance to change state depend on?

  -Strength of the forces between particles
• What are the limitations of particle models for changes in states?

  -In reality the particles aren't spherical solids- they're atoms, ions or molecules

  -Doesn't show the forces between the particles
• Describe structure of ionic compounds

  -regular structures (giant ionic lattices)

  -strong electrostatic forces of attraction in all directions between oppositely charged ions
• Why do ionic compounds have high melting and

  large amounts of energy needed to overcome the many strong bonds.
• Why can ionic compounds conduct electricity if they are dissolved in water/ melted?


  the ions are free to move and so charge can flow
• General properties of small molecules

  usually gases or liquids that have relatively low melting points and boiling points.

  Atoms held together with strong covalent bonds

  Weak intermolecular forces (forces of attraction)
• What happens when simple molecular substances melt/boil

  The weak intermolecular forces are broken, not the covalent bonds, therefore low melting/boiling points.
• Why do larger molecules have higher melting/ boiling points?


  As molecules get bigger, the strength of the intermolecular forces increases so more energy is needed to break them.
• Why small molecules don't conduct electricity?

  Molecules don't have an overall electric charge, so there are no free electrons or ions to carry charge.
• How are polymers linked to other atoms?

  By covalent bonds
• Why are polymers solid at room temperature

  The intermolecular forces between polymer molecules are larger than between simple covalent molecules, so more energy is needed to break them.
• Diagram of a polymer

  
• Examples of giant covalent structures

  Diamond, graphite, silicon dioxide

  
• Properties of giant covalen

  very high melting and boiling points

  don't conduct electricity- not even when molten

  -strong covalent bonds
• What must happen to the bonds in order to melt or boil a giant covalent structure

  Covalent bonds must be overcome, but lots of energy needed
• Describe structure of metals

  Giant structures of atoms with strong metallic bonding
• Why do most metals have a high mel

  Electrostatic forces between metal atoms and delocalised electrons are very strong, so need lots pf energy to be broken- solid at room temp
• Why can metals be bent and shaped.

  layers of atoms in metals are able to slide over each other; malleable
• Why are pure metals mixed with other metals to make alloys

  To make them harder
• What is an alloy?

  A mixture of two or more metals or a metal and another element