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Chemistry GCSE > 2.1 - Bonding, structure and particles > Flashcards

2.1 - Bonding, structure and particles Flashcards

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1
Q

What is an ionic bond?

A

When metals react with non metals, electrons are transferred from metals to the non-metal atoms forming ions (ionic compound)

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2
Q

In an ionic bond the metal becomes a ______ ion and the non-metal becomes a _______ ion
(positive/ negative)

A

positive

negative

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3
Q

There is a strong electrostatic force of attraction between these oppositely charged ions ionic bond. What does an electrostatic force mean?

A

A force of attraction between particles with opposite charges

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4
Q

When drawing an electronic structure of the ionic bond, Mg giving O 2 electrons. How would you display that Mg has given O 2 electrons ?

A

Draw out Mg and O electronic structure, take 2 of Mg electrons using arrows and give to O. Write Mg’s electronic structure within brackets with two less electrons and write at the top right 2+. Write O electronic structure with 2 more electrons in brackets with 2- top right.

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5
Q

What is a covalent bond?

A

2 non-metals share a pair of electrons to complete an outer shell.

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6
Q

Covalent bonds are _____ (strong/weak)
Substances with covalent bonds often form molecules with ____ (high/low) melting and boiling points, such as hydrogen and water.
These substances have ____ (strong/weak) covalent bonds within the molecules (between the atoms), These substances have ____ (strong/weak) intermolecular forces between the molecules.

A

Strong
Low
Strong
Weak

This means that only a small amount of heat energy is required to separate the molecules from each other

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7
Q

What is a molecule?

A

A collection of two or more atoms held together by chemical bonds

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8
Q

In NH^3 the Nitrogen and Hydrogen atoms have ____ (strong/weak) covalent bonds.
The forces of attraction between NH^3 molecules is ____ (strong/weak)

A

Strong

Weak

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9
Q

How can you calculate how many covalent bonds an element will form?

A

The number of covalent bonds is equal to eight minus the group number.
No of bonds

Group 4 [Carbon ] 8 - 4 = 4
Group 5 [Nitrogen] 8 - 5 = 3
Group 6 [Oxygen ] 8 - 6 = 2
Group 7 [Chlorine] 8 - 7 = 1

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10
Q

What is a compound?

A

A substance formed by the chemical union of two or more elements

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11
Q

The ions in a compound are arranged in a giant ionic lattice. This regular arrangement results in the formation of a _____

A

crystal - a solid containing particles joined together to form a regular arrangement or repeating pattern

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12
Q

What are the properties of an ionic compound?

A

Strong electrostatic forces between positive and negative ions means they have high melting / boiling points
Can’t conduct electricity as ions held firmly in place
When molten/ dissolved, ions are free to move so the ionic compound can conduct electricity

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13
Q

The greater the charge on the ions, the stronger the forces holding them together. Hence, the higher the melting and boiling point is.

A

Sodium chloride is made from Na+ ions and Cl– ions and has a melting point of 801°C. Magnesium oxide is made from ions with two charges (Mg2+ and O2–) and so has a much higher melting point of 2,852°C

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14
Q

Simple molecules contain only a few atoms held together by covalent bonds.
The covalent bonds holding the atoms together in a simple molecule are _____ (strong/weak)
The intermolecular forces between simple molecules are ____ (strong/weak)

A

strong

weak

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15
Q

What are the properties of simple molecular substances?

A

Low melting and boiling points – this is because little energy is needed to break the weak intermolecular forces.
Do not conduct electricity – this is because they do not have any free electrons or an overall electric charge in any state of matter.
Usually gases or liquids

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16
Q

Water is a simple molecular substance. When water melts or boils it is the weak intermolecular forces that break not the strong covalent bonds. What does this mean?

A

Water in liquid state - lot’s of H2O molecules joined together with other H2O molecules ( joined by intermolecular forces) and strong covalent bonds between the H and O atoms. Water once melted/ boiled - Weak forces between H20 molecules and other H20 molecules has been overcome and H20 molecules are no longer attached to one another and just singular H20 molecules.

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17
Q

Giant covalent structures contain very many atoms, each joined to adjacent atoms by covalent bonds. The atoms are usually arranged into giant regular lattices – extremely _____ (strong/weak) structures because of the many bonds involved

A

strong

18
Q

What is an allotrope?

A

A different form of the same element in the same state. E.g. diamond and graphite are allotropes of carbon.

19
Q

What are the properties of giant covalent structures?

A

Very high melting points - this is because a lot of strong covalent bonds must be broken
Variable electrical conductivity – diamond does not conduct electricity, whereas graphite contains free electrons so it does conduct electricity.

20
Q

What are the properties of Graphite with respect to bonding and structure?

A

Each carbon atom is covalently bonded to 3 other carbon atoms, forming layers of hexagonal rings
Layers slide over each other due to absence of covalent bonds between layers , but there are weak intermolecular forces between layers so graphite is soft and slippery
One electron from each carbon is delocalised so it can conduct electricity
Very high melting and boiling point because the strong covalent bond

21
Q

What are the properties of Diamond with respect to bonding and structure?

A

It is very hard
Doesn’t conduct electricity - no delocalised electrons
Has a very high melting point
Each carbon atom is joined to another four covalently - need a lot of energy to break

22
Q

What are fullerenes?

A

Molecules of carbon atoms with hollow shapes

They are based of hexagonal rings of carbo atoms, possibly contain rings of 5 or 7.

23
Q

What is a nanotube?

A

A long cylindrical molecule made from carbon atoms joined together by covalent bonds

24
Q

What is a ‘buckyballs’

A

A molecule comprising carbon atoms joined together to form a spherical or nearly spherical hollow structure

25
Q

What are the properties of Diamond with respect to its appearance and what it’s used for?

A

Colorless and transparent
Sparkle and reflect light (lustrous)
Jewelry
Hard, high melting point - useful in cutting tools

26
Q

What are the properties of Graphite with respect to its appearance and what it’s used for?

A

Black, shiny and opaque (not transparent or see through)
Slippery - used in pencil leads because layers slide on paper
Component for many lubricants (used on bike chain)

27
Q

What are the properties of Nanotubes?

A

Very high melting point - each carbon atom is joined to three other carbon atoms by strong covalent bonds. Good conductors of electricity - spare electron per carbon atom, which forms a sea of delocalised electrons within the tube

28
Q

What are the properties of metallic compounds?

A

The layers of ions are able to slide over each other, so metals are malleable (bent and shaped) and ductile ( drawn/pulled into wires
The delocalised electrons can move through the metal and carry charge, so metals conduct electricity and heat
Metallic bonds are strong and require large amounts of energy to be broken, giving most metals high melting and boiling points

29
Q

The metallic bond is the force of attraction between these ________ ______ and _______ metal ions

A

delocalised electrons

positive

30
Q

The greater the number of outer electrons that the metal has, the higher its melting/boiling point. Why is this?

A

This is due to the increased positive charge on the metal ion and the increased number of electrons that are delocalised, resulting in stronger bonding

31
Q

Aluminum (Group 3) Al –> Al^3+ + 3e-
Magnesium (Group 2) Mg –> Mg^2+ + 2e-
Sodium (Group 1) Na –> Na+ + 1e-

Does the melting/ boiling point increase or decrease?

A

Increase. Al at top. Na at bottom

32
Q

How small is a nanoparticle?

A

1-100 nm in diameter

1nm = 1 nanometer =1 x 10^-9m, which is 1 billionth of a meter

33
Q

What is Nano-silver used in?

A

Wound dressings to prevent infection
Coat the inside of socks/fridges to kill bacteria that causes bad smells
In deodorants to kill bacteria that causes bad smells
To disinfect water supplies on international Space Station

34
Q

What is Nano-scale particles of titanium dioxide used in?

A

Sunscreen to block harmful UV light.

Self cleaning windows as they help break down dirt

35
Q

What are the issues with Nano-scale particles?

A

Relatively new - unaware of long term effects
Particles are so small they could go into our blood stream and enter our cells
Could enter our environment and cause harm

36
Q

What are Smart materials?

A

Materials that have properties that can change reversibly - can change easily but can then easily change back, depending on changes in their surroundings

37
Q

What are the properties and uses of thermochromic pigments/ materials?

A

Change colour at specific temperatures
Used in mugs and spoons which change colour when there contents are hot
Also used in forehead thermometers

38
Q

What are the properties and uses of photochromic pigments?

A

Change colour when exposed to light
Used in sunglasses that darken in bright sun, but quickly change back to normal glasses when the lenses are no longer in sunlight

39
Q

What are the properties and uses of shape memory alloys/polymers?

A

These materials can be bent and deformed but will turn to their original shape when heated
Shape memory polymers are used in medical stiches (self tighten as wound heals) and sports equipment (gum shield)
Shape memory alloys are used in car bodies and plates for bone fractures

40
Q

What are the properties and uses of hydrogels / polymer gels?

A

Hydrogels can absorb up to 1,000 their volume in water
Certain stimuli (dryness, temp, Ph) can cause the water to be released
Used in nappies, fake snow, hair gel, artificial muscles, granules added to soil to help retain water for plants.

Chemistry GCSE (6 decks)

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