Bonding, structure and the properties

• What is ionic bonding?

  ionic bonding is the electrostatic attraction between positive and negative ions. It’s relatively strong.
• How are ionic compounds held together.

  They are held together in a giant lattice. it’s a regular structure that extends in all directions in a substance. Electrostatic attraction between positive and negative ions that hold the structure together.
• State the properties of ionic substances.

  High melting and boiling point (strong electrostatic forces between oppositely charged ions). when solid they do not conduct electricity (ions are fixed). Conduct when molten or dissolved in water as ions are free to move.
• How are ionic compounds formed?

  Metals react with non-metals. Electron transfers occur - metal gives away its outer shell electrons to non-metal.
• What’s a covalent bond?

  Covalent bond is a shared pair of electrons between 2 atoms.
• Describe the structure and properties of a simple molecular covalent substance.

  Do not conduct electricity. small molecules. Weak intermolecular forces meaning a low melting and boiling point.
• Depending on mass/size of the molecule, how does the intermolecular forces change?


  The intermolecular forces increase causing the melting and boing point to increase as more energy is needed to overcome these forces keeping the electrons in place.
• What are polymers?

  Polymers are large molecules with over 100 atoms linked by covalent bonds.
• What are thermo-softening polymers?

  Polymers that soften when heated. There are no bonds between polymer chains. strong intermolecular forces ensure the structure is solid at room temperature. These forces are overcome when heated so the polymer melts.
• What are giant covalent structures?

  Solids, atoms covalently bonded together in a giant lattice. Due to strong bonds they have high melting and boiling points. Most don’t conduct electricity as there’s no delocalised electrons. Some examples are diamond, graphite and silicon dioxide.
• Give 5 carbon allotropes.

  Diamond, fullerenes, graphite, nanotubes and graphene.
• Describe and explain the properties of diamond.

  4 strong covalent bonds for each carbon atom. Very hard (strong bonds). Very high melting point (strong bonds). Do not conduct.
• Describe and explain the properties of graphite.

  3 covalent bonds for each carbon atom. Layers of hexagonal rings. High melting point. Layers free to slide due to weak intermolecular forces between layers making it soft and a good lubricant. Conduct thermal and electricity due to a delocalised electron for each carbon atom.
• Describe and explain the properties of fullerenes.

  Hollow shaped molecule. Based on hexagonal rings but may be pentagonal or heptagonal. C60 has a spherical shape, simple molecular structure- buckministers fullerene.
• Describe and explain the properties of nanotube.

  Cylindrical fullerene with high length to diameter ratio. High tensile strength (strong bonds). Can conduct electricity due to delocalised electrons.
• What is graphene?

  A single layer of graphite.
• What is metallic bonding?


  Metallic bonding is the electrostatic attraction between the nucleus of positively charged metal ions and a sea of delocalised electrons.
• Describe the properties of metals.

  High melting/boiling points due to strong forces of attraction. Good heat and electricity conductors due to delocalised electrons. Malleable and soft as layers of atoms can slide over each other whilst maunting forces of attraction.
• What are alloys?

  Mixtures of metal with other elements (usually other metals).
• Why are alloys harder than pure metals.

  The different sized atoms distort the layers so they cannot slide over one another making them harder than pure metals.
• What does the amount of energy needed to change state (solid —> liquid) or (liquid —> gas) depend on?

  The strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and structure of the substance. The stronger forces between the particles the higher the melting point and boiling point of the substance.
• Pure substances will melt or boil at ..?

  A fixed temperature whilst mixtures melt over a range of temperatures.
• What are the three states of matter?

  Solid, liquid, and gas.
• What’s nano science?

  Science that studies the particles that are 1 - 100 nm in size.
• state the uses of nano particles.

  Medicine. Electronics. Deodorants. Sun creams for better coverage therefore more effective protection.
• What are fine and coarse particles?

  Fine particles and coarse particles refer to the size of particles in the air. Fine particles are 100 to 2500 nm in diameter, while coarse particles are 2500 nm to 10000 nm.
• Why do nano particles have properties different from the same materials in bulk?

  High surface area to volume ratio
• Define an intermolecular force.

  Forces which exist between molecules. The strength of the intermolecular force impacts its physical properties. E.g boiling/melting point.
• What’s a molecular formula?

  The actual ratio of atoms of each element present in a compound.
• Define particle theory.

  The theory modelling the three states of matter by representing each particle as a small solid sphere. It helps explain melting/boiling/freezing and condensing.