Bonding Structure And Matter Flashcards
What is ionic bonding?
Ionic bonding is the electrostatic attraction between positive and negative ions.
It is a relatively strong attraction.
How are ionic compounds held together? (3)
● They are held together in a giant lattice.
● It’s a regular structure that extends in all directions in a substance.
● Electrostatic attraction between positive and negative ions holds the structure together.
State properties of ionic substances (3)
● High melting and boiling point (strong electrostatic forces between oppositely charged ions)
● Do not conduct electricity when solid (ions in fixed positions).
● Conduct when molten or dissolved in water - ions are free to move.
How are ionic compounds formed? Explain in terms of MgO
Reaction of a metal with a non-metal.
Electron transfer occurs - metal gives away its outer shell electrons to non-metal.
Mg is in Group II, so has 2 available outer shell electrons. O is in Group VI, so can accept 2 electrons to get a full outer shell
configuration.
Mg becomes Mg2+ and O becomes O2− (oxide).
They become electrostatically attracted to one another (opposites attract) and form an ionic compound.
In this case (MgO) magnesium oxide.
What is a covalent bond?
Covalent bond is a shared pair of electrons between two or more atoms.
Describe the structure and properties of simple molecular covalent substances (4)
- Do not conduct electricity (no ions)
- Small molecules
- Weak intermolecular forces, therefore:
- Low melting and boiling points
How do intermolecular forces change as the mass/size of the molecule increases?
They increase. That causes melting/boiling points to increase as well (more energy needed to overcome these forces).
What are polymers?
What are thermosoftening polymers?
Polymers are very large molecules with atoms linked by covalent bonds.
Thermosoftening polymers melt/soften when heated.
There are no bonds between the polymer chains.
Strong intermolecular forces ensure that the structure is solid at room temperature. These forces are overcome with heating - polymer melts
Name factors (3) of and give examples (3) of giant covalent substances
- Solids, atoms covalently bonded together in a giant lattice.
- High melting/boiling points – strong covalent bonds.
- Mostly don’t conduct electricity (no delocalised e−)
- Diamond, graphite, silicon dioxide.
Name the 5 allotropes of carbon
Diamond
Graphite
Graphene
Fullerene
Nanotubes
Describe the structure and properties of diamond (4)
– four, strong covalent bonds for each carbon atom
– very hard (Strong bonds)
– very high melting point (strong bonds)
– does not conduct (no delocalised electrons)
Used in cutting tools and drill tips
Describe the structure and properties of graphite (5)
– three covalent bonds for each carbon atom
– layers of hexagonal rings
– high melting point
– layers free to slide as weak intermolecular forces
between layers; soft, can be used as a lubricant
– conduct thermal and electricity due to one delocalised
electron per each carbon atom
Used in pencil lead, as a lubircant and as an electrode (electrolysis)
Describe the structure and properties of graphene (1)
A single layer of graphite
Describe the structure and properties of fullerenes (3)
– hollow shaped molecules
– based on hexagonal rings
– C60 has spherical shape, simple
molecular structure (Buckminsterfullerene)
Describe the structure and properties of nanotubes (3)
- A cylindrical fullerene
- High tensile strength (strong bonds)
- Conductivity (deloc. electrons)