How bonding and structure are related to the properties of substances Flashcards
What does the amount of energy needed to change state from solid to liquid and liquid to gas depend on?
The strength of the forces between the particles of the substance
What does the nature of the particles involved depend on?
The type of bonding and the structure of the substance
The stronger the forces between the particles…
The higher the melting point and boiling point of the substance
What are the limitations of the simple model of solid liquid and gas
- No forces
- All particles are represented as spheres
- The spheres are solid
What is the structure of an ionic compound
Giant ionic lattice in which there are strong electrostatic forces of attraction in all directions between oppositely charged ions
Melting and boiling point of ionic compounds
High MP and BP-ionic bonds are strong, lots of energy needed to break the strong electrostatic force of attraction
What happens when ionic compounds are melted or dissolved in water
They conduct electricity because the ions are free to move and so charge can flow.
cant conduct when solid because the ions are fixed in place
What are substances that consist of small molecules usually ? Do they have high or low boiling points?
Gases or liquids with low melting and boiling point
What is overcome when a small molecule is melted
Intermolecular forces (NOT THE COVALENT BONDS) They are weak in these substances
What increases with size of the molecules
Intermolecular forces so the larger molecules have higher melting and boiling points
Do small molecules conduct electricity?
No because the molecules do not have an overall electric charge
Are polymers large or small molecules?
Very large
How are the atoms in polymers linked to other atoms?
By strong covalent bonds
Why are polymers solid at room temperature?
Because the intermolecular forces are strong between polymer molecules
Substances that consist of giant covalent structures are what
Solids with very high melting points
What is the structure of a giant covalent structure
All atoms linked to other atoms by strong covalent bonds
How would you melt or boil giant covalent structures
By overcoming the covalent bonds between atoms
Examples of giant covalent structures
Diamond, graphite and silicon dioxide (silica)
What are metals structure and how does link to their melting points
Giant structures of atoms with strong metallic bonding
therefore they mostly have high melting and boiling points
Why can metals be bent and shaped?
Layers of atoms in metals are able to slide over each other
What is an alloy?
A mixture of two or more metals
Why are alloys harder than pure metals?
The different sized atoms of the metals distort the layers in the structure, making it more difficult for them to slide over each other
Why are metals good conductors of electricity?
Because the delocalised electrons in the metal carry electrical charge through the metal
