Bonding and structure Flashcards
What is ionic bonding?
The electrostatic force of attraction between positively and negatively charged ions
What reacts in an ionic bond?
non- metal and metal
How can ionic bonding be represented?
Dot and cross diagram, ball and stick or 3D diagrams
What charge ions do these form?
Group 1
Group 2
Group 7
Group 1= +1
Group 2= +2
Group 7= -1
How are ionic compounds arranged?
In a lattice
What force is between ions in ionic compound?
electrostatic force
Do ionic compounds have strong or weak forces?
Strong electrostatic force
Do ionic compounds have high or low melting points?
high
Why do ionic compounds conduct electricity?
Once the ions are molten, or dissolved, they are free to move around. Therefore, the ions can carry their electrical charge through molten liquid or aqueous solution
What is an ion?
A charged atom or particle through the loss or gain of electron
What is covalent bonding?
The shared pair of electrons
What is covalent bonding between?
non-metals
How can covalent bonds be shown?
. dot and cross diagram
. line diagram
Do simple covalent molecules conduct electricity?
No because they have no delocalised electron to carry charge
Do simple molecular structures have low or high melting points? Why?
Low because although the atoms withing the molecules form strong covalent bonds, the intermolecular forces of attraction are very weak. So it need less heat energy to break intermolecular forces.
Why do simple molecular substances with big molecules have higher melting points?
AS molecules get bigger, strength of intermolecular forces increase. More energy is needed to break the intermolecular forces.
What is a polymer?
Lots of long covalently bonded molecules made of repeating sections
What does Eth at the beginning of a word mean?
2 carbons
What is polymerisation?
breaking double bonds so that it can attach to other monomers
What do alkenes have?
A carbon-carbon double bond
What is polymerisation?
Breaking down double bonds so that it can attach to monomers creating a polymer
What is a giant covalent?
Structures which contain many atoms joined by covalent structures. The atoms are arranged into a giant regular lattice
What is a lattice?
A structure that goes out in all directions in a regular pattern
Give examples of giant covalent structures
Diamond
Graphite
Graphene
Silicon dioxide
Explain the structure of graphite
.Layers slide off
.3 covalent bond so has delocalised electron
. Layers held together weakly
. Strong covalent bonds between carbon atoms
Explain the structure of graphene
.1 atom thick
.Strong covalent bonds between each carbon atoms
.The atoms are arranged in hexagons
. 3 covalent bonds so has delocalised electron
What is a use graphene?
. Touch screen
What is graphite used for?
.Pencil
Lubricant
Why is graphite used as a lubricant?
There’s weak bonds between the layers so can be separated easily by sliding over each other. This makes graphite slippery, so it is useful as a lubricant because it reduces the friction between two surfaces
What are allotropes?
Different structural forms of the same element in the same physical state
Name 4 allotropes of carbon
.Graphite
.Graphene
.Diamond
.Fullerenes
What are fullerenes?
Hollow molecules of carbon
What shapes can fullerenes be?
tubes or balls
Name uses of fullerenes
.In medicine- cage other molecules to deliver drug to where needed
. As catalysts because they have a large surface area to volume ratio
.In electronics as these nanotubes conduct electricity
. Strengthen material (add strength to material without adding much weight) e.g tennis racket
What might fullerenes someday be used for?
Lubricating and reducing friction in artificial joints
Describe the main features of metals in terms of their structure
Positive metal ions arranged in layers with delocalised electrons
Explain metallic bonding
In a metal, the outer shell electrons become delocalised- they are free to move through structure because and are not confined to one atom. The metal atoms become positively charged when they loses electrons so atoms are positive and delocalised electrons are negative. The electrons can move freely creating an electrostatic force of attraction because opposites attract ( positive atom ions and negative sea of delocalised electrons)
Why do metals have high melting points?
The electrostatic forces between metal ions and sea of delocalised electrons are very strong meaning it requires a lot of energy to be broken.
Why can metals conduct heat and electricity?
Metals have delocalised electrons that are free to move through structure. The moving electrons carry thermal energy and charge.
Why are metals malleable?
Metals consist of atoms held together in a regular structure. The atoms form layers that slide over each other. This means that they can be bent, shaped, hammered or rolled into shape
What are the limitations of dot & cross to represent a giant ionic structure?
. Don’t show the structure of compound
. No size of electrons
. Doesn’t show how atoms are arranged
What are the limitations of ball & stick diagrams?
.Ions are not to scale
. Suggests there are gaps between ions (there aren’t)
What is a limitation of 3D diagrams?
Only see the outer layer of compound
What does (aq) mean?
It’s in an aqueous solution
Why do gasses usually have small molecules?
The bigger the molecule, the stronger the intermolecular forces. Gases have weak intermolecular forces.
True or false:
Polymers have small molecules
False they have large molecules
Why are alloys harder than normal metals?
The smaller or bigger atoms distort the layers of atoms in the pure metal. This means that a greater force is required for the layers to slide over each other. The alloy is harder and stronger than the pure metal.
Describe the structure of diamond
In diamond, each carbon has 4 covalent bonds in a giant covalent structure, so diamond is very hard, has a high melting point and does not conduct electricity
.Lattice
.Strongcovalent bonds
What was the first fullerene discovered and what is it’s shape?
Buckminsterfullerene
spherical
True or false
Nanoparticles have high surface area to volume ratio
True
Name some uses of nanoparticles
.medical treatments
.cosmetics, deodorants and suncreams
.electronics
.catalysts
Name some possible risks of nanoparticles
.As they are so small you can inhale them and might catalyse harmful reaction
.Toxic
substances could bind to them because of their large surface area to volume ratios, harming health
What is the size of nanoparticles?
1-100nm
What is the size of fine particles?
100 and 2,500 nm
What is the size of coarse particles?
2,500-12,000nm
Describe the structure of a metal
Positive ions arranged in layers with negative ions. Arranged in a lattice. Have a delocalised electron
Why can fullerenes be good catalysts?
Large surface area to volume ratio
True or false:
Fullerenes are conductors
True
What state are most polymers at room temperature and why?
Solid because polymer have large molecules so the intermolecular forces are stronger than simple covalent structures so require a lot of energy to break them
Describe the structure and bonding in sodium chloride.
.Arranged in a lattice
.Ions held together by strong ionic bonds
.Na+ ions bonded to Cl- ions
.Strong electrostatic forces of attraction
