Bonding, Structure & Properties Of Matter Flashcards
1
Q
Ions
A
- charged particles; can be single atoms or groups of atoms
- lose or gain electrons to form full outer shell
- ‘stable electronic structure’
- full outer shell = stable
- metals lose electrons to form positive ions
- non-metals gain electrons to form negative ions
2
Q
Ionic Bonding
A
- metal loses electrons (+ve) and non-metal gains electrons (-ve)
- oppositely charged ions are attracted to each other by electrostatic forces
- this attraction is called an ionic bond
3
Q
Ionic Compounds Structure
A
- giant ionic lattice
- strong electrostatic forces of attraction between oppositely charged ions
- closely packed, regular arrangement
4
Q
Ionic Compounds Properties
A
- high melting and boiling points (lots of energy required to overcome the electrostatic forces of attraction)
- can’t conduct electricity as a solid (ions held in place)
- conduct electricity as a liquid/solution (ions free to move)
5
Q
Covalent Bonds
A
- non-metal elements share pairs of electrons
- positive nuclei attract shared pairs of electrons, making covalent bonds very strong
- only share electrons from their outer shells
- each bond provides one extra electron for each atom
- each atom makes enough bonds to fill outer shell - ‘stable electronic structure’
- covalent bonding can happen in non-metal compounds or elements
6
Q
Benefits and Limitations of Dot and Cross Diagrams
A
- electrons drawn in overlap of outer orbitals shows covalent bonds
- useful for identifying where each electron comes from
- don’t show sizes of atoms or arrangement
7
Q
Benefits and Limitations of Displayed Formula Diagrams
A
- shows how atoms are connected in large molecules
- doesn’t show 3-D structure or which atoms the electrons in the covalent bond have come from
8
Q
Benefits and Limitations of 3-D Models
A
- shows covalent bonds and arrangement in space
- gets confusing for large molecules with lots of atoms to include
- doesn’t show where the electrons for each covalent bond have come from
9
Q
Simple Molecular Substances Properties
A
- very strong intramolecular forces from covalent bonds
- intermolecular bonds are very weak
- melting and boiling points are very low - very little energy required to overcome weak intermolecular forces
- usually gases or liquids at room temperature
- MPs and BPs increase as molecules get bigger; stronger intermolecular forces
- don’t conduct electricity, as they aren’t charged (no free electrons or ions)
10
Q
Giant Covalent Structures
A
- all atoms are bonded together by strong covalent bonds
- very high MPs and BPs (strong intermolecular forces)
- don’t conduct electricity; no charged particles or free electrons (few exceptions, including graphite)
11
Q
Diamond Structure, Bonding and Properties
A
- each carbon atom forms 4 covalent bonds; very hard
- lots of energy required to break covalent bonds, so it has a very high MP and BP
- doesn’t conduct electricity; no free electrons or ions
12
Q
Graphite Structure, Bonding and Properties
A
- each carbon atom forms 3 covalent bonds, creating sheets of hexagonal patterns
- no covalent bonds between layers; very weak intermolecular forces, so it is malleable and can be used as a lubricant
- high melting point, as lots of energy is required to overcome strong covalent bonds
- each carbon atom has one delocalised electrons that is free to move; graphite can conduct electricity and heat
13
Q
Buckminsterfullerene Structure, Bonding and Properties
A
- 60 carbon atoms in a hollow sphere with 20 hexagons and 12 pentagons
- can be formed around another molecule to cage it (medical uses)
- industrial catalysts; large surface area
- good lubricating material
14
Q
Carbon Nanotubes Structure Bonding and Properties
A
- fullerenes can form tiny carbon cylinders
- very high length : diameter ratio
- can conduct electricity and heat very well
- high tensile strength (don’t break when stretched)
- used in nanotechnology or to strengthen material without adding much weight (e.g. tennis rackets)
15
Q
Metallic Bonding
A
- consist of a giant structure
- sea of delocalised electrons
- held together by strong electrostatic attraction between positive metal ions and delocalised electrons
- strong, regular structure, known as metallic bonding
- include metallic elements and alloys
16
Q
Metallic Substance Structure and Properties
A
- very high melting and boiling points, due to strong electrostatic forces
- good thermal and electrical conductors; sea of delocalised electrons
- malleable, as regular layers can slide over each other
17
Q
Alloys
A
- alloys are a mixture of a metal and one other element (usually another metal)
- differently sized atoms disrupt regular layers, so they are harder and less malleable
- more useful for certain jobs e.g. in construction
18
Q
Solid
A
- strong attractive forces between particles hold them together in fixed positions to form a very regular lattice arrangement
- keep a definite shape and volume (do not flow) as the particles don’t move from their positions
- particles vibrate around fixed positions
19
Q
Liquid
A
- weak force of attraction between particles; randomly arranged and free to move over each other (tend to stick closely together)
- definite volume but don’t keep a definite shape - flow to fill bottom of container
- particles constantly moving with random motion
20
Q
Gas
A
- almost no attractive forces between particles; free to move and are far apart; particles travel in straight lines
- don’t keep any definite shape or volume and will always fill any container
- move constantly with random motion
21
Q
Processes of melting and boiling/evaporating
A
- particles are heated and gain energy
- particles vibrate/move more, which weakens bonds holding them together
- at melting/boiling point, particles have enough energy to break their bonds
22
Q
Processes of freezing and condensing
A
- particles cool and lose energy, so move around less
- not enough energy to overcome attraction, so bonds are formed between particles
23
Q
State Symbols
A
s - solid
l - liquid
g - gas
aq- aqueous (dissolved in water)
24
Q
Nanoparticles
A
- diameter between 1-100nm (only a few hundred atoms)
- very very high surface area to volume ratio
- many more atoms exposed, so much less material needed; much more reactive
25
Q
Nanoparticles uses
A
- effective catalysts (SA:V ratio)
- nanomedicine; nanoparticles (e.g. fullerenes) are easily absorbed by body and could easily deliver drugs to right where they’re needed
- some conduct electricity; used in tiny electrical circuits for computer chips
- antibacterial purposes of silver nanoparticles - added to polymer fibres to make surgical masks/wound dressings or deodorants
- cosmetics e.g. moisturisers
- health risks not fully investigated
26
Q
Describe how an ionic bond forms
A
- metal element loses electrons and becomes positively charged
- non-metal element gains electrons and becomes negatively charged
- oppositely-charged ions attracted by electrostatic forces
27
Q
Describe structure of sodium chloride
A
- strong electrostatic forces hold ions together
- regular, ionic lattice arrangement
28
Q
List the main properties of ionic compounds
A
- high melting and boiling points
- conduct electricity when molten or in solution
- very hard due to strong electrostatic forces
29
Q
Describe how covalent bonds form
A
- non-metal elements share pairs of electrons
- strong electrostatic attraction between atomic nuclei and shared electrons hold atoms together
- multiple pairs of electrons can be shared at once
30
Q
Explain why simple molecular substances have low melting and boiling points
A
- strong intramolecular covalent bonds hold individual molecules together
- weak intermolecular forces are easy to overcome
- usually exist as gases or liquids
31
Q
Polymers
A
- lots of small units (monomers) linked together to form a large molecule that has repeating sections
- all atoms in a polymer are joined by strong covalent bonds
- strong intermolecular forces are difficult to overcome; mostly solid at room temperature
- weaker intermolecular forces than ionic or covalent bonds, so they will have lower melting/boiling points than giant ionic/covalent structures
32
Q
What type of bond occurs between carbon atoms in a diamond?
A
Covalent bonds
33
Q
Describe the structure of graphene
A
- single, atom-thick layer of carbon atoms
- each carbon atom covalently bonded to three other carbon atoms, forming hexagonal patterns
- one delocalised electrons from each carbon atom
34
Q
Explain how fullerenes could be used to deliver drugs to the body
A
- fullerene (hollow sphere of carbon atoms) formed around molecule
- easily absorbed by body
- goes right to wherever it is needed
35
Q
Explain why metallic substances can conduct electricity
A
- metallic substances contain delocalised electrons
- delocalised electrons are free to move around, carrying electrical charge
36
Q
Name the three states of matter
A
Solid
Liquid
Gas
37
Q
Name of the temperature at which a liquid becomes a gas
A
Boiling point
38
Q
State symbol for a solid
A
(s)
39
Q
Define a nanoparticle
A
- group of atoms between 1-100 nanometers
- usually less than a few hundred atoms
40
Q
Give three uses of nanoparticles
A
- medical uses: easy drug delivery method
- cosmetics: easily absorbed by body
- nanotechnology: used in tiny electrical circuits
- catalysts: high SA:V ratio makes them more effective than bulk material, as more atoms are exposed
- antibacterial purposes of silver nanoparticles: used in surgical masks/wound dressing or deodorants
