Bonding Flashcards
What is ionic bonding?
When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms forming ions. The result is an ionic compound.
When you gain an electron , what does the ion become?
Negative (non metals)
When you loose an electron, what does the ion become?
Positive (metals)
What is an ionic bond?
The strong electrostatic force of attraction between oppositely charged ions.
What are the properties of ionic compounds?
- strong
- regular structure
- high melting/boiling points
Explain why ionic compounds have such high melting points and boiling points
Ionic compounds, due to the strong electrostatic attraction, have a high melting/boiling point as this force is very difficult to break
What is covalent bonding?
When two non-metal atoms share a pair of electrons. The electrons are in the outer shell and covalent bonding completes its outer shell.
What is malleable and what is ductile ?
Malleable- moulded/ hammered into shape easily
Ductile- can be stretched into wires easily
What is the melting/boiling point of a covalent bond and why is this?
Covalent bonds have low melting and boiling points (like hydrogen and water). This is because despite how they have strong covalent bonds within the molecules, they have weak intermolecular forces (between molecules).
Can atoms form more than one covalent bond?
Yes, the number of covalent bonds will depend on how many electrons an atom needs to have a full outer shell.
What is a giant ionic structure?
A giant ionic structure is formed in an ionic compound. It is also known as a giant ionic lattice and this results in the formation of a crystal.
A giant ionic structure is repeated in all directions, giving a 3D shape.
Do solid ionic compounds conduct electricity?
No, the ions are held firmly in place leaning the ions cannot move to conduct electric current.
But, when the ionic compound melts, the charged ions are free to move, therefor molten ionic compounds do conduct electricity
Explain melting points in terms of charge
The greater the charge on the ions, the stronger the forces holding them together.
Or, the higher the charge the higher the melting point.
Explain the melting points and forces of simple covalent molecules
Covalent bonds are strong, Intermolecular forces are weak,
Low melting points,
Do not conduct electricity
Explain the melting points and forces of a giant covalent structure
Intermolecular forces are strong,
Covalent bonds are strong,
Very high melting point,
Variable electrical conductivity
Name some giant covalent structures
Graphite , diamond and sand.
Graphite can conduct electricity but diamonds cannot because diamonds are made up of tetrahedral diamond and are covalently bonded so there’s no free electrons. Whereas, graphite has free delocalised electrons which are free to move and conduct electricity unlike diamond.
What is a nano particle?
A particle that is very, very small and can be used in medicine, nanotubes or antibacterial soaps.
Name some uses for nanoparticles
Fridge coating- fridges can be lined with silver nano particles, this ensures that microbes are killed and do not spread to food or infect humans.
Nanotubes- these are extremely strong, electrical conductors and high tensile strength.
Antibacterial soap- silver nanoparticles can be used to eliminate bacteria, odour and be in the dressing of a wound.
Medicine- nanoparticles, like Bucky balls, have been used in medicine for targeted drug delivery or radiotherapy.
Sunscreen- nanoparticles of titanium oxide and zinc oxide are used in sunscreens. These nanoparticles absorb into the skin and help protect you from harmful UV rays.
What are some of the potential risks associated with using nanoparticles?
They could be absorbed into the body as they are so small. Also, this is a relatively new technology so not a lot is known about how they react to the body.
What are smart materials ?
Materials that react and change according to their environment
What is a piezoelectric smart material?
Change their shape in response to electrical impulses or produce electrical charge in response to mechanical stress
What is a shape memory smart material?
Can change shape or return to an original shape when exposed to a heat source
What is a photochromic smart material?
React to light, so the pigments change in response to ultraviolet lights
What is a thermochromic smart material ?
‘Thermo’ , in response to temperature like you see in colour changing mugs
What is the metallic bond?
The force of attraction between the free moving electrons and positive metal ions. Metallic bonds are strong, so metals can maintain a regular structure and usually have high melting/boiling points.
Explain how outer electrons effect bonding and melting points.
The greater the number of outer electrons that the metal had, the higher it’s melting/boiling point. This is due to the increased positive charge in the metal ion and the increased number of electrons that are delocalised , resulting in a stronger bond.
What is the size of 1 nanometre
1x10 ^-9 m (one billionths of a metre)
What is a hydrogel ?
Hydrogens can absorb up to 1,000 times their own volume in water. After this water has been absorbed, it can be released when it’s surrounding area dry. Therefor, it can be used in hair gel, nappies, and soil.
