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Chemical bonding

Terms in this set (48)

Metallic bonding
- Conductors in solid state
- Conductors in molten state
- Malleable and ductile
- Melting point is moderate to high
Ionic bonding
- Non conductors in solid state
- Conductors in molten state
- Hard and brittle
- High melting point
- Conductor when dissolved in water
Covalent molecular
- Non conductor in solid state
- Non conductor in molten state
- Non conductor when dissolved in water
- Soft
- Low melting point
Covalent network
- Non conductors
- Hard and brittle
- Very high boiling point
How do atoms of a metallic structure gain a noble gas configuration?
By releasing their valence electrons, they form positive metal ions and free electrons
Why are metallic structures good at conducting electricity?
The valence electrons of metallic structures are free moving . If a voltage is applied to a metal, electrons move towards the positive terminal
Why are metallic structures good at conducting heat?
Electrons within the sea of electrons are mobile and so can carry heat energy throughout the lattice.
Why are metallic structures malleable?
Bonding between metal ions and the sea of electrons is non-directional. Metal atoms can move in relation to each other without breaking the bonds between them and the sea of electrons.
Why do metals have high boiling points?
Strong attractive forces between the metal ions and sea of electrons hold the metallic lattice together. High temperatures are needed to disrupt such a strong lattice.
Compare the metallic structures of Sodium and Aluminium.
Both consist of an array of positive ions surrounded by a mobile sea of electrons. Sodium structure contains a positive 1 charge, Aluminium contains positive 3 charge.
What does it mean if a metallic structure of positive three?
Three electrons in sea of electrons for every ion
What combination forms an Ionic compound?
Non metal element and metal element
Name an Ionic compound
Sodium Chloride
Calcium Oxide
Magnesium sulphate
What does the metal element of the Ionic compound do?
Loses all of its valence electrons. The lost electrons transfer to the non-metal element which forms a negative ion also with a noble gas configuration.
Why is the bonding in the ionic lattice so strong?
Because of the strong electrostatic attraction between neighbouring negative and positive ions.
Why are ionic compounds poor conductors of electricity in the solid phase?
In an ionic solid the ions are tightly held in fixed positions within the lattice, thus they are unable to move and carry charge.
Why are ionic compounds good conductors of electricity when molten?
In molten phase, ions are free moving and carry charge throughout the ionic liquid. Both positive and negative ions carry charge. Positive ions move towards the negative electrode and the negative ions move towards the positive electrodes
Why are ionic compounds good conductors of electricity when in an aqueous solution?
In an aqueous solution individual ions from the ionic solid are mobile and free to move. Their mobility and charge enable them to conduct an electric current through the ionic solution.
Why are ionic compounds hard and brittle? -
If a large force is applied to the ionic lattice it will cause layers of ions to move. The electrons aren't free moving, so the ionic compound isn't malleable or ductile.
Why do ionic compounds have a high boiling/melting points
Ionic bonds are strong electrostatic attractive forces between ions. The strong attractive forces extend throughout the ionic lattice keeping individual ions in fixed positions.
Describe the formation of the ionic compound Calcium sulfide
When Calcium and Sulphur atoms touch a transfer of electrons occur. Each calcium atom loses two electrons forming a ca2+ ion while each sulphur atom accepts these two electrons to form a S-2 ion. The resulting atoms experience strong electrostatic attraction, causing them to arrange into a 3d array of positive and negative ions.
What combination makes up a covalent bond?
Two non-metals.
How is a noble gas configuration achieved with a covalent bond?
By sharing valence electrons between the bonded atoms.
Are covalent bonds directional?
Yes
Are ionic bonds directional?
No
Are metallic bonds directional?
...
What types of covalent bonds are there?
Single bonds, Double bonds and triple bonds.
What is a single-bond covalent bond?
When two atoms share two electrons
What is a double-bond covalent bond?
When two atoms share four valence eletrons
What is a triple-bond covalent bond?
...
Covalent molecular substances include...
Most non-metals and most compounds formed from a combination of non-metals only.
Why are covalent molceules non-conductors of electricity in either solid, liquid or aqueous phase?
The electrons in a covalent molecular substance are localised within each atom's electron cloud or as shared electrons within covalent bonds. None of these electrons are free to move independently.
Why are some covalent molecular bonds good conductors of electricity when in aqueous solution?
Covalent molecular substances which are acidic or basic react with water producing free mobile atoms. The resulting ions are able to move freely throughout the solution carrying charge and hence conducting an electric current.
Why are covalent
Strong molecular substances only form between the atoms within the molecules. Only weak intermolecular attractions occur between neighbouring molecules, this results in molecules being easily separated from one another, and these substances are now soft and weak.
Why do covalent molecular substances have low melting and boiling points?
When a molecular substance melts or boils, only the weak intermolecular forces need to be broken or overcome. The weakly bonded lattice of molecules in the solid phase is easily disrupted by heat energy to form a liquid or gas.
Why are ionic compounds poor conductors of electricity in the solid phase?
In an ionic solid the ions are tightly held in fixed positions within the lattice, thus they are unable to move and carry charge.
Why are ionic compounds good conductors of electricity when molten?
In molten phase, ions are free moving and carry charge throughout the ionic liquid. Both positive and negative ions carry charge. Positive ions move towards the negative electrode and the negative ions move towards the positive electrodes
Why are ionic compounds good conductors of electricity when in an aqueous solution?
...
Why are ionic compounds poor conductors of electricity in the solid phase?
In an ionic solid the ions are tightly held in fixed positions within the lattice, thus they are unable to move and carry charge.
Why are ionic compounds good conductors of electricity when molten?
...
Why are ionic compounds poor conductors of electricity in the solid phase?
...
Name an Ionic compound
Sodium Chloride
Calcium Oxide
Magnesium sulfate
What does the metal element of the Ionic compound do?
Loses all of its valence electrons
What is the reason of the metallic lattice bonding?
Strong electrostatic attraction between still metal ions
Define nano particles
Particles with at least one dimension in the 1-100 nanometre range.
Name two examples of nanoparticles that do not involve carbon
Sunscreens (Zinc Oxide)

Quantum dots (Zinc Sulphate)
What is a nano composite?
Made by adding nano sized particle of one material to a matrix of a bulk material, such as metal, polymer or ceramic
Define nano technology
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