C2.1 + 2 Structure and Bonding + Structure and Properties Flashcards Preview

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Flashcards in C2.1 + 2 Structure and Bonding + Structure and Properties Deck (46)
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1

What is the mass number?

Total number of protons and neutrons of an atom

2

What is the atomic number?

Total number of protons/electrons

3

Define a 'compound'.

Substances in which atoms of two or more elements are chemically combined

4

Define an 'isotope'.

Different atomic forms of the same elements, with the same atomic number but a different number of neutrons.

5

Name two isotopes of carbon.

Carbon-12 and Carbon-14

6

What is an ionic bond?

A bond formed between metals and non-metals

7

Describe how an ionic bond happens.

- The metal loses its electrons and becomes positively charged
- The non-metal gains those electons and become negatively charged.
- The positive metal ion and negative non-metal ion are attracted to each other and the compound is ionically bonded

8

Why do atoms bond?

To gain a full outer shell and become energetically stable

9

What group in the periodic table has a full outer shell?

Group 0 - the noble gases

10

How do Group 1 elements react with non-metals?

The alkali metals (group 1) only have one electron in their outer shell. They lose this electron to have a full outer shell and become a metal ion with a single positive charge

11

How do Group 7 elements react with metals?

The halogens (group 7) have 7 electrons in their outer shell. They gain another electron from a metal to have a full outer shell and become halide ions with a single negative charge.

12

Describe the structure of an ionic compound.

- They form giant ionic lattices
- There are strong forces of electrostatic attraction between oppositely charged ions

13

Describe and explain the properties of giant ionic compounds.

- High melting points = strong forces of electrostatic attraction between the ions that take a high amount of energy to overcome.
- Conductors of electricity when molten = the ions are free to move and can carry electric current.
- Conductors of electricity when dissolved in water = the ions separate and are free to move and carry current

14

What carries electric current?

Moving electrons/ions

15

Work out the ionic formula of sodium chloride.

- Sodium chloride contains Na (1+) and Cl (1-)
- Swap over the charge numbers (here it's sort of pointless but whatever) Na1 and Cl1.
- Formula = NaCl (metal always goes first)

16

Work out the ionic formula of magnesium chloride.

- Magnesium chloride contains Mg (2+) and Cl (1-)
- Swap over the charge numbers so Mg1Cl2
- Formula = MgCl2 (small numbers)

17

What are the two types of covalent bonding?

- Simple molecular covalent bonding
- Giant covalent structures

18

Describe the bonds between simple molecular substances.

- The atoms form very strong covalent bonds to form small molecules
- However, the intermolecular forces are very weak

19

Describe and explain the properties of simple molecular substances.

- They have low melting/boiling points as the weak intermolecular forces are easy to break.
- They are usually gases/liquid at room temperature
- They don't conduct electricity as there are no ions so no electrical charge.

20

Name 3 examples of simple molecular substances

- Water
- Oxygen
- Chlorine

21

Give three examples of substances of giant covalent structures.

- Diamond
- Graphite
- Silicon dioxide

22

Describe and explain the properties of diamond.

- Each carbon atom forms four covalent bonds in a tight rigid structure so it is very hard.
- It doesn't conduct electricity as there are no free electrons and no ions.
- It has a very high melting point as there are strong covalent bonds between the atoms with strong intermolecular forces
- It is insoluble as its covalent bonds are stronger than the H20 bonds so they can't be hydrated.

23

Describe and explain the properties of silicon dioxide.

- Each silicon atom forms four covalent bonds in a tight rigid structure so it is very hard.
- It has a very high melting point as there are strong covalent bonds between the atoms with strong intermolecular forces.
- It is insoluble as its covalent bonds are stronger than the H20 bonds so they can't be hydrated.

24

Describe and explain the properties of graphite.

- It is soft and slippery as each carbon atom only forms three covalent bonds, creating layers which are free to slide over each other. The layers only have weak intermolecular forces between them making it easier for them to slide across each other.
- It is a good conductor of heat and electricity (the only non-metal). Each carbon atom has a delocalised electron which can move and carry electrical charge.

25

Describe the structure of metallic structures.

They are giant structures of atoms arranged in a regular pattern. Delocalised electrons hold the atoms together in this structure as there are strong forces of electrostatic attraction between the positive metal ions and the negative electrons.

26

Draw a giant ionic lattice.


27

Draw a metallic structure


28

Describe and explain the properties of giant metallic structures.

- They are good conductors of heat and electricity as it has delocalised electrons which are free to move and carry charge.
- They are bendy and easy to shape, as the layers of atoms can slide over each other.
- They have high melting/boiling points as the strong forces of electrostatic attraction are difficult to overcome.

29

What are alloys?

A mix of two or more metals

30

What is an important property of alloys? Explain the reason for it.

- They are far harder than normal metals.
- This is because the different sized atoms distort the layers of metal atoms making them more difficult to slide over each other.

31

Why do metallic structures have delocalised electrons?

The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.

32

Is the covalent bond or the intermolecular forces overcome when a simple molecular substance melts/boils?

The intermolecular forces

33

What do shape memory alloys do?

They can return to their original shape after being deformed after being heated above a certain temperature.

34

Explain one use of shape memory alloys.

Nitinol in dental braces, it warms in the mouth and tries to return to its original shape, pulling the teeth with it.

35

Describe and explain the properties of thermosoftening polymers.

- They melt easily as they have weak intermolecular forces between individual tangled polymer chains which take little energy to break.
- They are easy to remould as the layers of polymer chains can slide over each other due to the weak intermolecular forces.

36

Describe and explain the properties of thermosetting polymers.

- They don't melt when heated as there are strong intermolecular forces (cross links) holding the polymer chains in a solid structure.
- This is also why they are hard and not easily bent.

37

What two factors do the properties of polymers depend on?

- What they were made from (their starting materials)
- What conditions they were made under (their reaction conditions)

38

How is low density polyethene (LD) made?

By heating ethene to about 200 degrees under high pressure.

39

Name 2 uses of low density polyethene and the property that makes these suitable.

- Bottles
- Plastic bags
- It is very flexible.

40

How is high density polyethene (HD) made?

At a lower temperature and pressure than LD (with a catalyst).

41

Name 2 uses of high density polyethene and the property that makes these suitable.

- Water tanks
- Drainpipes
- It is very rigid

42

How big are nanoparticles?

1 - 100 nanometres across

43

What are fullerenes?

They are molecules of carbon arranged in hexagonal rings shaped like hollow balls/closed tubes.

44

What are 2 important properties of nanoparticles?

- High surface area to volume ratio
- Different properties from the 'bulk' material they are made out of

45

Name some uses of nanoparticles.

- New industrial catalysts
- New computers (they conduct electricity so can make tiny circuits to use in chips)
- Highly sensitive sensors - ones that detect one type of particle and nothing else
- Stronger lighter building materials

46

Describe 2 uses of fullerenes.

- New lubricant coatings which reduce friction used in artificial joints and gears
- To deliver drugs right into the cells as fullerenes are easily absorbed by the body.