From Models to Materials (DP IB Chemistry)
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What are the three general types of bonding?
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What are the three general types of bonding?
The three general types of bonding are:
Ionic
Covalent
Metallic
True or False?
Chemical bonding can be strictly categorized into three distinct types.
False.
Chemical bonding is a continuum of ionic, covalent, and metallic bonding.
Define electronegativity.
Electronegativity is the ability of an atom to attract electrons in a chemical bond.
Using the bonding triangle diagram, which two pieces of information are required to identify the type of bonding in an element or binary compound?
Using the bonding triangle diagram, the two pieces of information that are required to identify the type of bonding in an element or compound are:
The average electronegativity of the component elements
The difference in electronegativity of the component elements
How is the average electronegativity of two elements. A and B calculated?
The average electronegativity of two elements A and B is:
(Electronegativity of A + electronegativity of B) / 2
(χA + χB) / 2
True or False?
Average electronegatitivty is on the y-axis of the bonding triangle diagram.
False.
Average electronegatitivty is on the x-axis of the bonding triangle diagram.
Difference in electronegativity is on the y-axis.
How is the difference in electronegativity between two elements A and B calculated?
The difference in electronegativity between two elements A and B is:
Electronegativity of A - electronegativity of B
χA - χB
What does the bonding triangle represent?
The bonding triangle represents the continuum of ionic, covalent, and metallic bonding, determined by electronegativity values.
True or False?
Elements have a non-zero difference in electronegativity on the bonding triangle.
False.
Elements have zero difference in electronegativity and are found along the x-axis of the bonding triangle.
Where are ionic compounds typically located on the bonding triangle?
Ionic compounds are typically located in the top middle part of the bonding triangle.
Add the missing labels to complete the bonding triangle diagram.
The completed bonding triangle diagram is:
How is the position of a compound determined in the bonding triangle?
The position of a compound in the bonding triangle is determined using the electronegativity of elements and binary compounds.
More specifically using the average electronegativity and difference in electronegativity of the elements.
True or False?
The bonding triangle assesses the percentage of ionic or covalent character in a compound.
True.
The bonding triangle assesses the percentage of ionic or covalent character in a compound.
What is the significance of the average electronegativity in the bonding triangle?
The average electronegativity determines the position along the x-axis of the bonding triangle.
What is the significance of the electronegativity difference in the bonding triangle?
The electronegativity difference determines the position along the y-axis of the bonding triangle.
How does the bonding triangle help in predicting properties of compounds?
The bonding triangle allows for a more accurate assessment of bonding type and the prediction of associated properties.
Where are covalent compounds typically located on the bonding triangle?
Covalent compounds are generally found at the bottom right of the bonding triangle.
What does the position of a binary compound on the bonding triangle indicate about its bonding character?
The position of a compound on the bonding triangle indicates the relative proportions of ionic, covalent, and metallic character in its bonding.
Will a chemical with an average electronegativity of 1.1 and difference in electronegativity of 0.3 conduct electricity?
A chemical with an average electronegativity of 1.1 and difference in electronegativity of 0.3 will conduct electricity.
Explain why elements can only be classified as metallic or covalent bonding.
Elements can only be classified as metallic or covalent bonding because they have an electroengativity difference of 0, which means that they are at the bottom of the bonding triangle.
Which substance, M, N, O, or P, is polar covalent?
Substance O is polar covalent.
Which substance, M, N, O, or P, has low covalent character?
Substance N is high in the ionic bonding region of th bonding triangle, which means that it will have low covalent character.
Which substance, M, N, O, or P, can conduct electricity when solid?
Substance M can conduct electricity when solid, because it has metallic bonding.
What is an alloy?
An alloy is a mixture of metals, where the metals are mixed together physically but are not chemically combined.
State two advantages of using alloys over pure metals.
Advantages of using alloys over pure metals are:
Greater strength
Greater hardness
Increased resistance to corrosion
Increased resistance to extreme temperatures
True or False?
Alloys can only be made from metals.
False.
Alloys can also be made from metals mixed with non-metals, such as carbon.
How are ions arranged in an alloy?
In an alloy, ions of different metals are spread throughout the lattice and are bound together by delocalized electrons
What allows for the formation of alloys?
Alloys can be formed due to the non-directional nature of metallic bonds.
Explain why alloys are harder than pure metals.
The increased hardness and strength of an alloy is caused by the different size atoms which distort the regular arrangements of atoms, preventing the layers from sliding over each other easily.
True or False?
Alloys are chemically combined mixtures of metals.
False.
Alloys are physical mixtures of metals, where the metals are not chemically combined.
How do properties of alloys differ from pure metals?
Alloys often have greater strength / hardness, or resistance to corrosion / extreme temperatures compared to pure metals.
Name the two main elements in steel alloys.
The two main elements in steel alloys are iron and carbon.
True or false?
Brass is an alloy of copper and tin.
False.
Brass is an alloy of copper and zinc.
Give one use of stainless steel.
Uses of stainless steel include:
Cutlery
Sinks
Chemical plants
What is a polymer?
A polymer is a large molecule of high relative molecular mass made by linking together large numbers of smaller molecules called monomers.
What is a monomer?
A monomer is a smaller molecule that links together to form a polymer.
What type of bonds connect monomers in a polymer?
Monomers in a polymer are connected via covalent bonds.
What is a macromolecule?
A macromolecule is a relatively large molecule compared with other molecules, such as a polymer.
Give two examples of a synthetic polymer.
Examples of a synthetic polymer include:
Resins
Plastics
Polystyrene (cups)
Nylon
Give two examples of a natural polymer.
Examples of a natural polymer include:
Proteins
DNA
Starch
True or False?
All polymers contain just one type of monomer unit.
False.
Some polymers contain just one type of unit, while others contain two or more different types of monomer units.
What is a copolymer?
A copolymer is a polymer that contains two or more different types of monomer units.
Give two examples of copolymers.
Two examples of copolymers are nylon and biological proteins.
State two types of linkage that can exist between monomer units in a polymer.
Linkages between monomer units in polymers include:
Covalent bonds
Amide links
Ester links
What is the process called when many monomers bond together to form a polymer?
The process of many monomers bonding together to form a polymer is called polymerization.
What does 'n' represent in polymer repeating units?
In polymer repeating units, 'n' represents the number of monomers in the polymer.
True or False?
Polymers made from alkenes are generally non-polar and unreactive.
True
Polymers made from alkenes are generally non-polar and unreactive.
Why are polymers / plastics often light-weight?
Polymers / plastics are often light-weight because they are low density due to the loose packing of their chains.
Why are polymers strong?
Polymers are strong because they contain many strong covalent bonds between the monomers / within the structure.
Describe addition polymerisation.
Addition polymerisation is a type of polymerisation in which monomers add together to form a polymer chain without the loss of any molecules.
What is the name of the addition polymer formed from the following alkene?
The name of the polymer formed from the following alkene would be (poly)propene.
What is X?
X is the repeating unit.
What is the structure of the monomer that forms this polymer?
The monomer which forms the polymer is:
What happens to the π-bond in C=C during addition polymerization?
During addition polymerization, the π-bond in each C=C bond breaks and then the monomers link together to form new C-C single bonds.
What is a repeat unit in a polymer?
A repeat unit is the smallest group of atoms that when connected one after the other make up the polymer chain.
In poly(alkenes) and substituted poly(alkenes), how is the repeating unit of a polymer different to the monomer?
In poly(alkenes) and substituted poly(alkenes), the repeating unit is the same as the monomer except that the C=C double bond is changed to a C-C single bond
Name two common addition polymers.
Common addition polymers include:
Poly(ethene)
Poly(chloroethene) (PVC)
Poly(propene)
Poly(styrene)
What type of bond must a monomer contain to undergo addition polymerization?
A monomer must contain at least one C=C double bond to undergo addition polymerization
True or False?
The section of the polymer chain shown inside square brackets is the monomer.
False.
The section of the polymer chain shown inside square brackets is the repeat unit, not the monomer.
