Bonding Basics
What is an intramolecular bond?
A bond within a substance, holding atoms together.
Where are the outer electrons found in a metallic bond?
electrons around the positive metal ions.
What holds an ionic compound together?
Strong electrostatic forces of attraction between oppositely charged ions.
What type of atoms are found in a covalent network?
Non-metal atoms, such as carbon or silicon.
What is a polymer?
A large molecule made from many repeating units called monomers joined together
What are the three physical properties of water?
Solid, liquid and gas are its three states of matter.
What is the difference between intra and intermolecular forces?
Intramolecular forces are within a molecule; intermolecular forces are between molecules
Why are metals able to conduct electricity?
Their delocalised electrons can move freely through the structure.
Why are ionic substances brittle?
When layers shift, like charges become aligned, causing strong repulsion and the lattice to fracture.
In a 2D covalent network, how many carbon atoms is each carbon atom bonded to?
Three
What is a polymer chain made up of?
It is made up of repeating monomer units joined by covalent bonds.
What is a polar molecule?
A molecule with an uneven distribution of charge, giving it partial positive and partial negative regions.
Which is stronger: intermolecular or intramolecular bonds?
Intramolecular bonds are generally much stronger.
Why are metals ductile?
Layers of metal ions can slide past one another while remaining attracted to the delocalised electrons.
Why do ionic substances have high melting points?
They have strong electrostatic attractions between oppositely charged ions, requiring lots of energy to overcome.
How many covalent bonds does each carbon atom form in a 3D covalent network such as diamond?
Four
What type of bonding holds the atoms together within a polymer chain?
Strong Covalent Bonds
What determines the density of a metal?
Its mass and volume, which depend on the atoms present and how closely they are packed.
A substance has a high boiling point. What does this suggest about the forces holding its particles together?
The forces between its particles are strong, so more energy is needed to separate them.
Explain why metallic bonding is strong.
There is a strong electrostatic attraction between positive metal ions and the sea of delocalised electrons throughout the structure.
Explain why an ionic compound conducts electricity when molten but not when solid.
When solid, the ions are fixed in position. When molten, the ions are free to move and carry charge.
Explain why diamond has a very high melting point.
Each carbon atom forms four strong covalent bonds in a giant 3D network. A large amount of energy is required to break these bonds.
What forces hold neighbouring polymer chains together?
Intermolecular forces between the polymer chains.
What gas in the atmosphere reacts with aluminium that causes the protective coating to rust?
Oxygen
Explain why boiling a molecular substance involves overcoming intermolecular forces rather than breaking the covalent bonds within molecules.
Boiling separates molecules from each other, so the intermolecular attractions are overcome. The covalent bonds within each molecule remain intact.
Explain how metallic bonding accounts for both the electrical conductivity and ductility of metals.
Delocalised electrons can move through the structure and carry charge. The attraction between the ions and electron sea remains as layers of ions shift, allowing metals to deform rather than shatter
Compare the structure and properties of an ionic compound with those of a metal.
Ionic compounds contain positive and negative ions in a lattice, while metals contain positive metal ions surrounded by delocalised electrons. Ionic compounds are brittle, whereas metals are generally malleable and ductile.
Compare a 2D covalent network with a 3D covalent network in terms of bonding and structure.
In a 2D network, each carbon bonds to three others, producing layers. In a 3D network, each carbon bonds to four others, producing an extended 3D structure.
Explain why polymer chains can make plastics flexible.
The atoms within each polymer chain are held together by strong covalent bonds, but there are weaker intermolecular forces between neighbouring chains. The chains can therefore move and slide relative to one another, allowing the plastic to bend and be flexible.
Why is duralumin stronger than pure aluminium, and approximately what percentage of copper is used in a common strong duralumin alloy?
Adding copper and other elements disrupts the regular arrangement of aluminium atoms and makes the layers harder to slide, increasing strength. A commonly cited composition is around 4% copper.