Structure and Bonding Flashcards
What are ions?
Charged particles than can be single atoms (Cl^-) or groups of atoms (NO3^-)
Which groups of elements readily/easily form ions?
Groups 1,2,6 and 7
How do groups 1 and 2 form ions?
Metals, lose electrons to form positive ions (cations)
How do groups 6 and 7 form ions?
Non-metals, gain electrons to form negative ions (anions)
What does it mean if elements are all in the same group?
They have the same number of outer electrons, form ions with the same charges
What is ionic bonding?
When a metal and a non metal react together.
- metal loses electrons (+ve)
- non-metal gains these electrons (-ve)
- strong electrostatic forces
- oppositely charged ions
What is an ionic compound?
- Structure of a giant ionic lattice
- made up of ions
What is a giant ionic lattice?
- closely packed lattice arrangement- structure
- strong electrostatic forces between oppositely charged ions
What are properties of ionic compounds?
- High melting and boiling points (strong electrostatic bonds), needs lots of energy to overcome
- Solid= fixed position, can’t conduct electricity
Melted= free to move, carry electrical charge - Some dissolve in water-> ions free to move, carry electrical charge
What are covalent bonds?
When non-metal atoms bond together, sharing a pair of electrons
- electrostatic forces, strong
- in non-metal elements and compounds
What are simple molecular substances made up of?
Made up of molecules containing a few atoms joined by covalent bonds
What are some examples of simple molecular substances?
- Hydrogen
- Chlorine
- Oxygen
- Nitrogen
- Methane
- Water
- Hydrochloric acid (Hydrogen Chloride)
What are properties of simple molecular substances?
- Simple molecular structures
- Strong covalent bond, weak intermolecular forces
- Low Melting and Boiling point (to melt you only need to break the weak intermolecular forces)
- Most are gas or liquid at room temp
- as molecules get bigger, strength of intermolecular forces increases, more energy needed -> Melting and Boiling point increases
- No charge, don’t usually conduct electricity
What are Polymers?
- lots of small units linked by strong covalent bonds to form a long molecule
- More energy needed to break them -> intermolecular forces are larger in simple covalent molecules
- lower boiling points than ionic or giant molecular structures (weak intermolecular forces)
What are Giant covalent structure features+ examples?
- High melting and boiling points (strong covalent bonds)
- Don’t conduct as solid or molten (apart from exceptions like graphite etc)
- Diamond, Graphite, Silicon dioxide (silica)
- Macromolecules
What are the features of Diamond?
- Each carbon forms 4 covalent bonds, Very rigid structure
- High melting point, strong covalent bonds
- Doesn’t conduct electricity
- Carbon allotrope
What is Graphite ?
- forms 3 covalent bonds, creates layers of hexagons
- No bonds between layers, free to more over each other-> soft slippery
- ideal as a lubricant
- high melting point (covalent bonds in the layers)
- 1 delocalised electron per atom, conducts electricity and thermal energy
What are the features of the structure of Silicon Dioxide (silica)?
- Silicon and Oxygen
- What sand is made of
What is an allotrope?
Different structural forms of the same physical element in the same physical state
What is graphene?
- a single layer of graphite
- sheet of carbon atoms joined in hexagons
- 1 atom thick
- strong (covalent bonds, light -> can be added to materials to improve strength without adding much weight
- delocalised electrons, conduct electricity-> can be used in electronics
What are Fullerenes?
Molecules of carbon, shaped like hollow balls or small tubes
- Can be arranged as hexagons, pentagons or heptagons (rings of carbon atoms)
- Cage other molecules-> deliver drugs into the body
- Huge SA-> industrial catalysts, lubricants
What is the Buckminsterfullerene?
- First fullerene to be discovered
- C60
- Forms hollow sphere
What are nanotubes?
Tiny carbon cylinders, formed from fullerenes
- can conduct electricity and thermal energy
- high tensile strength (don’t break when stretched)
- nanotechnology-> used in electronics, strengthen materials without adding weight (tennis racket frames)
What is metallic bonding?
Strong electrostatic attraction between positive metal ions and delocalised electrons
- strong
- metallic elements, alloys
- delocalised electrons produce properties of metal
- high melting point (strong electrostatic forces)
- Solid at room temp
- good conductors of electricity and heat (delocalised electrons)
- Malleable (bent, hammered, rolled into sheets) ,layers of metal can slide over each other
