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Year 8 science 2023 > Chemistry Bonding Unit > Flashcards

Chemistry Bonding Unit Flashcards

1
Q

Why does magnesium lose two electrons?

A

To have a stable electronic configuration the atom loses two electrons in the outer shell.

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2
Q

Why does oxygen gain two electrons?

A

To become stable it gains 2 electrons so the outer shell is full.

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3
Q

Describe the formation of sodium oxide.

A

-Sodium oxide forms an ionic bond through the transfer of electrons
-Two sodium (metal) atoms each donate 1 electron to an oxygen (non-metal) atom forming two sodium ions with a charge of 1+
-The oxygen (non-metal) atom accepts 2 electrons forming an oxide ion with a charge of 2-
-The electrostatic force of attraction between the positive sodium ions and the negative oxygen ion forms an ionic bond and therefore the compound sodium oxide

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4
Q

What are ionic compounds also?

A

Salts

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5
Q

Acid + metal >

A

Salt + hydrogen

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6
Q

What structure do Ionic compounds form?

A

Giant ionic lattice structure

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7
Q

Why does the giant ionic lattice have to be giant?

A

Because there can be an infinite number of ions.

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8
Q

Why does the giant ionic lattice have to be a lattice?

A

Because it is a repeated three-dimensional arrangement.

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9
Q

What is an ionic bond?

A

Strong electrostatic force of attraction between oppositely charged ions in a giant ionic lattice.

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10
Q

What are the 4 properties of ionic bonds?

A

-Solubility
-Melting and Boiling points
-Conductivity
-Brittleness

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11
Q

Why do most ionic compounds dissolve in water?

A

-Water molecules are able to attract positive cations and negative anions, pulling them apart and breaking electrostatic forces of attraction between ions so the ions are now free-floating

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12
Q

Why do ionic compounds have high melting and boiling points?

A

The strong electrostatic forces of attraction between ions require lots of energy (i.e temperature) to break the bonds

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13
Q

What needs to happen for a substance to conduct electricity?

A

In order for a substance to conduct electricity, it must contain freely moving charged particles (i.e electrons or ions)

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14
Q

Why do solid ionic compounds not conduct electricity?

A

-Ions in a solid ionic compound are not free to move
-They’re held together by strong electrostatic forces fo attraction

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15
Q

Why do dissolved/molten ionic compounds conduct electricity?

A

-Ions are free to move and carry electrical charge
-The strong electrostatic force of attraction have been broken by water or heat

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16
Q

Why do ionic compounds break very easily/are brittle?

A

When a force is applied, the ions in the lattice shift so that like ions repel and the lattice breaks

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17
Q

Define allotrope.

A
  • Different forms of the same element
  • I.e Different arrangement of covalent bonding leads to different properties of giant structures
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18
Q

What is a giant covalent structure?

A

Many atoms joined by covalent bonds to form a continuous three-dimensional network (lattice)
-E.g Diamond, graphite and sand

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19
Q

What is covalent bonding?

A

Electrostatic force of attraction between the nuclei of two atoms and a shared pair of electrons between then.

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20
Q

How do ionic bonds form?

A

Transfer of electrons.

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21
Q

Between what substances do ionic bonds form?

A

Ionic compounds form between non-metals and metal elements

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22
Q

Between what two substances do covalent bonds form?

A

Non-metals

23
Q

Between what two substances do metallic bonds form?

A

Metals

24
Q

Explain why graphite conducts electricity whereas diamond does not.

A

To conduct electricity, there must be free-flowing charges. Graphite has delocalized electrons whereas diamond does not.

25
Q

Explain why diamond is hard.

A

Strong covalent bonds between carbon atoms require lots of energy to break.

26
Q

What is metallic bonding?

A

-Electrostatic force of attraction between delocalized electrons and positive metal ions.
-Metals form giant structures in which electrons in the outer shells of the metal are free to move

27
Q

What must you label when drawing a metallic bond?

A
  • Lattice structure (of 4 atoms)
  • Electrostatic force of attraction between metal cation and electron
  • Metal cation
  • Sea of delocalized electrons
28
Q

How do metal cations form

A

By losing their valence electrons

29
Q

What are the three properties of all metals?

A

-Conductivity (electricity)
-Conductivity (heat)
-Malleable and ductile

30
Q

Why are metals able to conduct electricity?

A

Metals contain delocalized electrons which can move freely through the structure and carry the charge

31
Q

Why are metals able to conduct heat?

A

-The metal ions are closely packed together and when heated they vibrate, passing heat energy through the metal
-Delocalized electrons also move through the structure transporting heat energy

32
Q

What does it mean for metal to be ductile and malleable?

A

-Metals are able to be hammered or pressed into shape without breaking or cracking
-Metals can also be drawn out into wires

33
Q

Why are metals malleable and ductile?

A

-Strong electrostatic force of attraction between cations and delocalized electrons don’t break
-However, layers within the lattice structure can easily slide over each other, causing the shape of the metal to change

34
Q

Compare the brittleness of metals and ionic compounds.

A

-When a force is applied to an ionic compound, the ions in the lattice shift so that like ions repel and the lattice breaks
-Whereas in metals, there is a strong electrostatic force of attraction between cations and delocalized electrons that doesn’t break. Layers within the lattice structure can easily slide over each other

35
Q

Compare the conductivity of electricity in solid ionic compounds and metals.

A

-There are no free-flowing charged particles in a solid ionic compound to carry charge whereas in a metal there are delocalized electrons that are free to move through the structure and carry charge

36
Q

Define an alloy.

A

An alloy is a mixture of two or more metals
-It can sometimes be a mixture of 2 or more elements where at least one element is a metal (e.g carbon and iron make steel)
-Man made materials

37
Q

Why do we make alloys?

A

-Many pure metals are too soft for many uses
-Make a pure metal harder by adding another element (alloy)
- An alloy often has more uses than the pure elements it is made from

38
Q

Why are alloys much harder than pure metals

A

-Since an alloy has atoms of different sizes, this distorts the layers of atoms so they are no longer regular. Therefore, it is harder for layers to slide over each other and more force is required to move the layers. Thus, the alloy is harder and stronger

39
Q

What is reactivity?

A

A measure of how readily and violently a substance will react with another substance

40
Q

What is displacement?

A

Displacement is when a more reactive metal takes the place of another one in a compound

41
Q

Why is francium the most reactive element in group 1?

A

Francium since it has the most shielding between the nucleus and the valence shell, the force of attraction is weaker on the valence electron therefore it is easier to lose and the element is more reactive.

42
Q

Why would steel be a more practical use of iron?

A

-It is harder and stronger because layers are no longer regular and don’t slide over each other as easily

43
Q

What are the 4 materials used to reduce iron in a blast furnace?

A
  • Iron ore (haematite) which contains iron oxide
  • Coke (carbon)
  • Limestone (calcium carbonate)
  • Air (oxygen)
44
Q

What is the purpose of iron ore ( the iron oxide in the ore Fe2O3)?

A

A compound that contains iron (desired element)

45
Q

What is the purpose of coke?

A

-Burns in the air to produce heat
-Reacts to form carbon monoxide (required to reduce the iron ore)

46
Q

What is the purpose of limestone?

A

-Helps to remove impurities from iron ore
-When this reacts with iron ore it produces slag

47
Q

What is the purpose of air (oxygen)?

A

Allows the coke to burn, producing heat

48
Q

What happens inside a blast furnace?

A

-Iron ore reacts with carbon monoxide
-Iron is displaced from its oxide
-Now it called cast iron

49
Q

What is slag used for?

A

Slag can be used to build roads and make cement

50
Q

What is the purity of cast iron?

A

96%

51
Q

Explain how electricity is conducted in a metal?

A

-Metallic bonds are formed when metals lose outer shell electrons to form metal cations surrounded by a sea of delocalized electrons
-These delocalized electrons are free-floating and able to move throughout the cation lattice
-This means that when a current is applied, the free floating electrons are able to carry the charge
-Hence conducting electricity

52
Q

Explain why metals have high melting points (e.g copper)

A

-Metallic bonds are formed when metals lose outer shell electrons to form metal cations surrounded by a sea of delocalized electrons
-Metal cations have a strong electrostatic force of attraction to negative delocalized electrons
-These bonds are strong and require large amounts of energy to break
-Hence why metals (copper) have a high melting point

53
Q

Explain how heat is conducted in a metal?

A

-Metallic bonds are formed when metals lose their outer shell electrons to form metal cations surrounded by a sea of delocalized electrons
-The metal ions are closely packed together and when heated they vibrate passing heat energy through the metal
-Delocalized electrons also move through the structure transporting heat energy
-Hence, conducting heat

54
Q
A

Year 8 science 2023 (6 decks)

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