Bonding, Structure and Properties Flashcards

1
Q

What are substances made up of?

A

Atoms

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2
Q

What are elements made up of?

A

Only on type of atom

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3
Q

What does the top number of an element tell you?

A

The relative atomic mass and the total mass of the atom (proton and neutron number)

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4
Q

What does the bottom number of an element tell you?

A

The atomic number and the number of protons and electrons

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5
Q

What properties of metals are there?

A

Good conductors of electricity
High melting and boiling points
Strong

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6
Q

What is a compound?

A

A substance in which 2 or more elements are chemically combined.

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7
Q

What 3 types of chemical bonds are there?

A

Ionic
Metallic
Covalent

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8
Q

What is ionic bonding?

A

The transfer of electrons from a metal to a non metal

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9
Q

Explain the process of ionic bonding

A

Where an atom (usually a metal) loses electrons from its outer shell to become a positively charged ion, these electrons are donated to another atom (usually a nonmetal) which becomes a negatively charged ion. The strong attraction between the negative and positive charges form an ionic bond.

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10
Q

What is covalent bonding?

A

The sharing of electrons between non metals

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11
Q

What do atoms in metals form?

A

A regular giant lattice structure arrangement.

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12
Q

What properties do metals have and why?

A

Metals are good thermal conductors due to the ions within the lattice being held closely together, so vibrations caused by heat are passed on easily.

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13
Q

What allows the metals to conduct electricity?

A

The movement of delocalised electrons within the structure.

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14
Q

What are the properties of a giant ionic structure?

A

High melting and boiling points due to strong bonds
Conduct electricity only when dissolved in water or molten so that the ions are free to move and carry an electric current.
Brittleness

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15
Q

Describe the structure of a simple molecular structure.

A

Atoms form strong covalent bonds in small molecules, but the interactions between them are very weak.

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16
Q

Properties of simple moleculars

A

Low melting and boiling points due to the weak forces. Most are gases or liquids at room temperature.
Don’t conduct electricity or dissolve in water.

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17
Q

Describe the structure of a giant covalent structure.

A

Atoms are held in a giant covalent lattices by strong covalent bonds.

18
Q

Properties of giant covalent

A

Very high melting and boiling points due to all the atoms being held by covalent bonds.
They are insoluble in water
They don’t conduct electricity even when molten as they have no free electrons of ions.

19
Q

Properties of diamond

A

Very high melting point
Extremely hard (used for glass cutting and drills)
Electrical insulator

20
Q

Reasons for diamond

A

Carbon has 4 outer electrons and forms 4 covalent bonds. The strong bonds make it hard. It cannot conduct electricity as there are no ions or free electrons.

21
Q

Properties of graphite

A

Very high melting point
Very soft as a result used as a lubricant in machinery and in pencils.
Electrical conductor

22
Q

Reasons for graphite

A

Carbon atoms form 3 covalent bonds. Making up a layer of carbons in a hexagonal structure. This leaves a free electron per carbon which is free to move along the layers which let it conduct electricity.

23
Q

What is graphene made of?

A

A single layer of graphite molecules

24
Q

What can graphene be used for?

A

It’s so thin that it can be used in inks and electronics

25
Q

What are buckyballs made of?

A

60 carbon atoms joined together

26
Q

What can buckyballs be used for?

A

Can be used in medicine to transport drugs to specific parts of the body.

27
Q

What are carbon nanotubes used for?

A

Reinforcing materials e.g. tennis rackets

28
Q

What is the size of a nanoparticle?

A

1-100nm

29
Q

How big is a nanometre?

A

1x10^-9m

30
Q

Disadvantages of nanoparticles?

A

No research of the after effects and the properties are very different and unpredictable due to the change of size of the particles.

31
Q

What is nano-silver used for?

A

Has antibacterial properties which kill bacteria so they can be used in fridges to make food last longer.

32
Q

What is titanium dioxide used for?

A

Sunscreen, Titanium dioxide nanoparticles are so small they do not reflect visible light, so they don’t appear white on the skin. They also block harmful UV lights.

33
Q

What is gold and silicon used for?

A

The particles absorb much more sunlight efficiently which is why they are useful in solar panels.

34
Q

What makes a smart material a smart material?

A

Smart materials have properties that change reversibly with a change in their surroundings.

35
Q

What is thermochromic?

A

Organic molecules in ink and paint that change colour as a result of temperature change.

36
Q

What is photochromic?

A

Organic molecules in ink and paint that change colour as a result of light especially UV. The light breaks bonds and the atoms are rearranged to form molecules of a different colour.

37
Q

What is a shape memory alloy?

A

Some alloys in particular some nickel/titanium and copper/aluminium/ nickel has two remarkable properties. Pseudoelasticity and shape-retention memory.

38
Q

What are shape memory polymers?

A

These are somewhere between thermoplastics and thermostats. When heated the polymer softens and it can be stretched and deformed. On cooling, it remains the deformed state. On being reheated it ‘remembers’ and returns to its original shape.

39
Q

Similarities between thermochromic and photochromic?

A

They both react to a stimuli.

40
Q

What is a hydrogel?

A

Cross linked polymers that have the ability to absorb or expel water when subjected to certain stimuli. They can be used in nappies. E.g. change in temperature or pH