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Chemistry > Topic 1 > Flashcards

Topic 1 Flashcards

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1
Q

Describe the Dalton model of an atom?

A

Atoms were solid spheres made up of different elements

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2
Q

Describe J.J thomsons model of an atom? (plum pudding model)

A
  • Atoms werent solid spheres

- They contain even smaller negatively charged particles - electrons

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3
Q

Describe Rutherfords gold foil experiment?

A
  • He fired positively charged alpha particles at a thin sheet of gold
  • they expected particles to pass through or be slightly deflected at most but whilst most did go through, some were deflected more than expected and a small number were deflected backwards
  • Discovered theres a tiny positively charged nucleus at the centre, surrounded by a cloud of negative electrons
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4
Q

Describe the bohr model of an atom?

A

Electrons only exist in fixed orbits, or shells and each shell has a fixed energy

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5
Q

What do scientific experiments have to be backed up by…

A

Evidence

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6
Q

What are the three subatomic particles that make up an atom and what are their relative masses/charges

A
  1. Protons (Relative mass: 1, Relative charge: + 1,
  2. Neutrons (Relative mass: 1, Relative charge: 0)
  3. Electrons (Relative mass: 0, Relative charge: -1)
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7
Q

What is the charge of an atom overall?

A

Neutral

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8
Q

Are the number of protons equal to the number of electrons?

A

Yes

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9
Q

Is the mass number the top or bottom number?

A

The top number

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10
Q

What are isotopes?

A

Different forms of the same element, which have the same number of protons but a different number of neutrons

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11
Q

Why does the existence of isotopes result in RAM not always being a whole number?

A

If an element has more than one isotope, its Ar is the average of the mass numbers of all the different isotopes, taking into account how much there is of each one. So it might not be a whole number

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12
Q

How can you work out RAM from isotopic abundances?

A
  1. Multiply each relative isotopic mass by its isotopic abundance, and add up the results
  2. Divide by the sum of the abundances
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13
Q

How did Mendeleev arrange the periodic table

A
  • he put elements with similar chemical properties in columns
  • he realised some ended up in wrong columns (due to isotopes). Whenever this happened, he switched the order of the elements to keep those with similar properties in the same column
  • gaps were left due to undiscovered elements but he was still able to predict their properties
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14
Q

How does the periodic table look today?

A
  • the elements are in order of atomic number
  • groups correspond to outer electrons
  • periods represent another full shell of electrons
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15
Q

How many electrons can go in the first, second and third shells?

A

1st shell: 2
2nd shell: 8
3rd shell: 8

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16
Q

Where do you separate metals from non metals in the periodic table?

A

from aluminium, it looks like a staircase

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17
Q

Outline what ions are?

A

They are charged particles

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18
Q

When do negative ions form?

A

When an atom gains electrons

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19
Q

When do positive ions form?

A

When an atom loses electrons

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20
Q

How do you work out an ionic compounds chemical formula?

A

By swap and switch method

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21
Q

Ionic bonding forms between…

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A

A metal and a non metal

22
Q

What is an ionic bond?

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A

A bond that is created by oppositely charged ions being strongly attracted to one another by electrostatic forces

23
Q

Recall dot and cross diagrams?

Study These Flashcards
A

Practise questions on them

24
Q

What type of structures do ionic compounds have?

Study These Flashcards
A

Giant ionic lattice structures

25
Why do ionic compounds have high melting and boiling points?
Because it takes a large amount of energy to overcome the strong attraction between the ions
26
Why dont solid ionic compounds conduct electricity?
Because the ions are fixed in place and cant carry a current
27
Why can ionic compounds conduct electricity when they are melted/dissolves?
Because the ions can move and can carry a current
28
Evaluate the use of 2D representations to show structures?
They are good at showing what atoms something contains and how they are connected, but they dont show the shape of the substance and the size of the atoms
29
Evaluate the use of dot and cross diagrams to show structures?
They show how compounds or molecules are formed and where the electrons in the bonds or ions came from, but they dont show anything about size or arrangement of atoms
30
Evaluate the use of ball and stick models to show structures?
They help visualise structures as they show shape of lattice/molecule - More realistic than 2D drawings - They are misleading as they make it look like there are gaps between atoms - but this is where electron clouds interact - They dont show correct sizes of atoms
31
Covalent bonds are formed when...
a pair of electrons is shared between two atoms to create molecules
32
What is the average size of atoms/small molecules
10 (-10) m
33
Recall covalent bonds between certain molecules
Recall from guide
34
What are some properties of simple molecular substances?
- they have low melting and boiling points as their intermolecular forces are very weak but as the molecules get bigger, so do the strength of these forces so the melting and boiling points increase - They dont conduct electricity as they dont contain any free moving delocalised electrons - Some are soluble, whilst others are not
35
What are polymers?
- Molecules made up of long chains of covalently bonded carbon atoms e.g. poly(ethene) - They're formed when lots of small Molecules called monomers join together
36
Describe the structure of diamond?
1. It's made up of a network of carbon atoms that each form four covalent bonds 2. they have high mp's as lots of energy is needed to break the bonds 3. Diamond is really hard due to the rigid lattice structure 4. It doesnt conduct electricity as it has no free moving delocalised electrons or ions
37
Describe the structure of graphite?
1. Each carbon atoms only forms three covalent bonds, creating sheets of carbon atoms arranges in hexagons 2. Its soft and slipper as layers can move over each other (no covalent bonds) so they can be used as a lubricating material 3. high melting points as a lot of energy is needed to break covalent bonds 4. Conducts electricity as it has one free moving electron in an atom
38
What's graphene?
One layer of graphite
39
What are fullerenes?
- molecules of carbon, shaped like closed tubes or hollow balls, arranged in hexagons/pentagons(buckminsterfullerene)/heptagons - they can be used to cage other molecules . This could be used to delivers drugs directly to cells in the body - They have a huge surface area so they'd make great industrial catalysts
40
Define empirical formula?
The smallest ratio of atoms in a compound
41
How do you work out empirical formula?
Empirical formula = mass/ mr
42
What is the equation to work out moles from mass and mr?
moles = mass / mr
43
What is the equation to work out concentration from mass and volume?
conc = mass/volume
44
How do you convert cm(3) to dm(3)
divide by 1000
45
How do you calculate the amount of product from a limiting reactant?
1. write out balanced equation 2. work out RFM of the reactant and product you're interested in 3) work out moles of the substance you know the mass of 4) work out how many moles is in the other product by looking at ratios 5) use moles to calculate mass
46
What causes metallic bonding?
the electrostatic force between positive metal ions and shared negative electrons holds atoms in a regular structure. This is metallic bonding
47
What are 6 properties of metals?
1. they're very strong 2. they arent soluble in water 3. dense 4. high melting and boiling points 5. malleable (layers of atoms slide over each other) 6. good conductors of heat and electricity
48
What are 4 properties of non metals?
1. more brittle (than metals) 2. dull looking 3. lower boiling points (than metals) 4. dont conduct electricity
49
Whay may final mass increase in a reaction?
1. before reaction, gas is floating in air but not contained in reaction vessel so you can't measure its mass 2. when gas reacts to form part of the product, it becomes contained in the reaction vessel 3. so the total mass inside vessel increases
50
Why may mass decrease in a reaction?
Gas may be lost in the reaction (as product is forming) if the reaction vessel isnt enclosed and so the total mass in reaction vessel decreases

Chemistry (7 decks)

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