Flashcards in Bonding, structure and properties of matter Deck (23)
What are ions?
(metals lose electrons to become positive ions but non-metals lose electrons to become negative ions)
What is ionic bonding?
Bonding between a metal and non-metal.
Explain ionic bonding
Metal atom loses electrons to form a positively charge ion.
Non-metal gains these electrons to form a negatively charged ion.
These oppositely charged ions are attracted to one another by electrostatic forces.
What structure do ionic compounds have?
giant ionic lattice
(regular lattice arrangement with very strong electrostatic forces of attraction between oppositely charged ions in all directions of the lattice)
What properties do ionic compounds have?
-high melting and boiling points (due to strong bonds between ions which need lots of energy to overcome)
-when they're solid, the ions can't conduct electricity
-when they're molten or dissolved in water, they can conduct electricity because the ions are free to move and to carry the current
What is covalent bonding?
Bonding between non-metals
Explain covalent bonding
non-metal atoms share electrons in their outer shells so that each atom has enough covalent bonds to have a full outer shell.
What properties do simple covalent molecules have?
-very low melting and boiling points (very weak intermolecular forces that are easily overcome)
-don't conduct electricity
What properties do giant covalent structures have?
-very high melting and boiling points (as lots of energy is required to break the strong covalent bonds)
-generally don't conduct electricity
What is diamond like?
giant covalent structure made up of carbon atoms that each form 4 covalent bonds
-very hard (^^)
-very high melting point (due to covalent bonds)
-doesn't conduct electricity (no free electrons)
What is graphite like?
giant covalent structure made up of carbon atoms that each form 3 covalent bonds, creating sheets of carbon atoms
no covalent bonds between layers, just weak forces. this makes graphite soft and slippery
high melting point (covalent bonds require lots of energy to break)
conducts electricity and thermal energy
What is graphene like?
one layer of graphite (just one atom thick!)
-conducts electricity and heat
What are fullerenes?
molecules of carbon shaped like closed tubes or hollow balls
mainly arranged in hexagons (or pentagons or heptagons)
How can fullerenes be used?
-catalysts (because of large surface area)
-to deliver a drug (cage the drug)
What is nanotechnology?
Technology that uses very small particles like nanotubes
What is metallic bonding?
bonding between metals
Explain metallic bonding
The electrons in the outer shell of the metal atoms are delocalised. There are strong forces of attraction between the positive metal ions and shared electrons.
What is the difference between alloys and pure metals?
Pure metals are just one element and are too soft for most jobs so they're mixed with other elements to form alloys. As the different elements have different sized atoms, the new atoms distort the layers of the metal atoms, making it more difficult for them to slide over eachother. This makes alloys much harder than pure metals.
What is the size of the diameter of a coarse particle?
between 2500 nm and 10,000 nm
What is the size of the diameter of a fine particle?
between 100 nm and 2500 nm
What is the size of the diameter of a nanoparticle?
between 1 nm and 100 nm
What can nanoparticles be used for? (And why?)
• to make new catalysts (nanoparticles have a large surface area to volume ratio)
• nanomedicine (nanoparticles are more easily absorbed by the body eg. to deliver drugs)
• tiny electrics circuits (some nanoparticles conduct electricity)
• in cosmetics
• to add antibacterial properties for surgical masks, wound dressings, deodrants, etc. (silver nano particles have antibacterial properties)