Bonding, Structure & Properties Of Matter

Question 1

Ions

Answer 1

• 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

Question 2

Ionic Bonding

Answer 2

• 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

Question 3

Ionic Compounds Structure

Answer 3

• giant ionic lattice
• strong electrostatic forces of attraction between oppositely charged ions
• closely packed, regular arrangement

Question 4

Ionic Compounds Properties

Answer 4

• 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)

Question 5

Covalent Bonds

Answer 5

• 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

Question 6

Benefits and Limitations of Dot and Cross Diagrams

Answer 6

• 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

Question 7

Benefits and Limitations of Displayed Formula Diagrams

Answer 7

• 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

Question 8

Benefits and Limitations of 3-D Models

Answer 8

• 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

Question 9

Simple Molecular Substances Properties

Answer 9

• 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)

Question 10

Giant Covalent Structures

Answer 10

• 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)

Question 11

Diamond Structure, Bonding and Properties

Answer 11

• 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

Question 12

Graphite Structure, Bonding and Properties

Answer 12

• 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

Question 13

Buckminsterfullerene Structure, Bonding and Properties

Answer 13

• 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

Question 14

Carbon Nanotubes Structure Bonding and Properties

Answer 14

• 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)

Question 15

Metallic Bonding

Answer 15

• 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

Question 16

Metallic Substance Structure and Properties

Answer 16

• 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

Question 17

Alloys

Answer 17

• 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

Question 18

Solid

Answer 18

• 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

Question 19

Liquid

Answer 19

• 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

Question 20

Gas

Answer 20

• 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

Question 21

Processes of melting and boiling/evaporating

Answer 21

• 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

Question 22

Processes of freezing and condensing

Answer 22

• particles cool and lose energy, so move around less

- not enough energy to overcome attraction, so bonds are formed between particles

Question 23

State Symbols

Answer 23

s - solid
l - liquid
g - gas
aq- aqueous (dissolved in water)

Question 24

Nanoparticles

Answer 24

• 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

Question 25

Nanoparticles uses

Answer 25

• 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

Question 26

Describe how an ionic bond forms

Answer 26

• metal element loses electrons and becomes positively charged
• non-metal element gains electrons and becomes negatively charged
• oppositely-charged ions attracted by electrostatic forces

Question 27

Describe structure of sodium chloride

Answer 27

• strong electrostatic forces hold ions together

- regular, ionic lattice arrangement

Question 28

List the main properties of ionic compounds

Answer 28

• high melting and boiling points
• conduct electricity when molten or in solution
• very hard due to strong electrostatic forces

Question 29

Describe how covalent bonds form

Answer 29

• 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

Question 30

Explain why simple molecular substances have low melting and boiling points

Answer 30

• strong intramolecular covalent bonds hold individual molecules together
• weak intermolecular forces are easy to overcome
• usually exist as gases or liquids

Question 31

Polymers

Answer 31

• 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

Question 32

What type of bond occurs between carbon atoms in a diamond?

Answer 32

Covalent bonds

Question 33

Describe the structure of graphene

Answer 33

• 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

Question 34

Explain how fullerenes could be used to deliver drugs to the body

Answer 34

• fullerene (hollow sphere of carbon atoms) formed around molecule
• easily absorbed by body
• goes right to wherever it is needed

Question 35

Explain why metallic substances can conduct electricity

Answer 35

• metallic substances contain delocalised electrons

- delocalised electrons are free to move around, carrying electrical charge

Question 36

Name the three states of matter

Answer 36

Solid
Liquid
Gas

Question 37

Name of the temperature at which a liquid becomes a gas

Answer 37

Boiling point

Question 38

State symbol for a solid

Answer 38

(s)

Question 39

Define a nanoparticle

Answer 39

• group of atoms between 1-100 nanometers

- usually less than a few hundred atoms

Question 40

Give three uses of nanoparticles

Answer 40

• 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