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[OBSELETE] Edexcel - A Level Chem > Topic 1 > Flashcards

Topic 1 Flashcards

1
Q

What is the structure of an atom?

A

A nucleus containing protons and neutrons surrounded by electrons in electron shells.

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2
Q

What are the relative mass and charges of protons, neutrons and electrons?

A
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3
Q

What is an atomic number and Mass number?

A

Atomic / Proton number - Amount of Protons OR Electrons

Mass Number = Amount of Protons AND Electrons

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4
Q

How to find the number of each subatomic particle

A

12 - 6 = 6 Neutrons

6 = 6 Protons

6 = 6 Electrons

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5
Q

What are isotopes?

A

Isotopes are atoms of the same element but different numbers of neutrons.\
- Same chemical properties ← same electron configuration
- Different Physical Properties ← different isotopic mass

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6
Q

What is relative isotopic mass?

A

Mass of an atom of an isotope compared to 1/12th of a carbon atom

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7
Q

What is relative atomic mass?

A

Ar is the weighted mean mass of an atom of an element compared to 1/12th of a carbon atom
(We use carbon because of the mass of carbon is 12)

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8
Q

How do you calculate Ar from isotopic abundances?

A
  • Multiply each isotopic abundance with the isotopic mass
  • Add up all the results
  • Divide by 100
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9
Q

What is a Mass Spectrometer?

A

Devices that find out what samples are made up of by measuring their masses

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10
Q

How does a mass spectrometer work?

A

Ions are sent at a high speed and are deflected and depending where they are detected on the electromagnet you are able to see the mass as

A moving force will be deflected if a force of a higher strength makes contact in another direction

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11
Q

What is step 0 in mass spec?

A

Step 0 - Preparation

  • Samples must be vaporised to be GASEOUS
  • Mass spec must be in a Vacuum to avoid collision with air molecules
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12
Q

What is step 1 is mass spec

A

Step 1 - Ionisation

  • Electrons are knocked off the atoms using a electron gun
  • This then turns the atom into a ion

Example H(g)→ H(g)+

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13
Q

What is step 2 in mass spec

A

Step 2 - Acceleration

  • Positively charged plates launch the ions
  • Negatively charged plates then accelerate the ions
  • This is done to ensure all ions have the same kinetic energy

All this is done in an electric field

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14
Q

What is step 3 in mass spec

A

Stage 3 - Deflection

  • A Magnetic field then deflects the ions
  • Separation of ions occur because the more charged an ion is the more its deflected
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15
Q

What is step 4 in mass spec?

A

Stage 4 - Detection

  • The beams of electrons are then detected electronically
  • This is recorded through Mass charge ratio (M/z)
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16
Q

How do you analyse mass spectra?

A
  • Height of each peak = relative isotopic abundance
  • The m/z of each isotope is the isotopic mass
17
Q

How do you work out relative atomic mass Ar from mass spectra?

A
18
Q

How do you predict the mass spectra of diatomic molecules?

A

When chlorine is ionised you get unstable chlorine ions

Cl2→Cl2+

The unstable ions then get fragmented where the atoms can’t be accelerated so their lost

Cl2+→Cl + Cl+

This means that Cl+ ions will be detected and give out lines at 335 and 37

HOWEVER some Cl2+ ions will also be detected meaning that there will be peaks at:

70 = 35 + 35

72 = 35 + 37

74 = 37 + 37

19
Q

How to calculate relative formula mass

A

This only works because the molecular ion is the sum of all the relative molecular masses

20
Q

What is ionisation energy?

A

Ionisation energy is the energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions

21
Q

What is successive ionisation energy?

A

The energy required for the removal of the second electron form the ion such as that 1 mole of gas with +1 ion gives +2 ions

22
Q

What factors effect ionisation energy?

A

Nuclear Charge

More protons ⇒ more positively charged nucleus ⇒ stronger attraction ⇒ harder to remove electron

Ionic radii

Electron shells further away ⇒ higher ionic radii ⇒ less attraction ⇒ easier to remove electron

Electron Shielding

More electron shells (shielding) ⇒ less attraction to nucleus ⇒ easier to remove electron

23
Q

Why is there a general increase in first ionisation energy?

(across a period)

A

Across a period first ionisation energy increases:

  • Electron number increase (increasing nuclear charge)
  • Shielding would stay the same
  • Ionic radii would decrease
  • Meaning overall first ionisation energy increases
24
Q

Why is there a general decreases in ionisation energy down a group?

A

First ionisation energy decreases down a group:

  • Electron number increases (no increase in nuclear charge as…)
  • Shielding increases
  • Atomic radii increases (reducing the nuclear charge)
  • Meaning that overall first ionisation energy decreases
25
Q

What is electron configuration?

A

The distrabution of electrons among electoron orbitals

26
Q

What is a quantum shell?

A
  • The energy level of an electron
  • Like an electron shell
27
Q

What evidence is there for electron configuration?

A
  • Emission spectra provides evidence of quantum shells
  • Successive ionisation energies is evidence for quantum shells within atom suggesting the group which an element belongs to
  • First ionisation energy provides evidence for electron subshells
28
Q

What effect does electron configurations have on an element?

A
  • The more electron shells there is
  • The higher the shielding
  • The higher the ionic radii
  • The weaker the forces of attraction between the nucleus and the outer electron
29
Q

What are orbitals and what types are there?

A
  • An orbital is a clouds of negative charge within an atom that can hold up to two electrons with opposite spins
  • S orbital = 2 electrons
  • P orbital = 6 electrons
  • D orbital = 10 electrons
30
Q

What is the shape of the s-orbital?

A
31
Q

What is the shape of the p-orbital?

A
32
Q

What are s,p,d block on the periodic table?

A
  • S Block (Groups 1,2)
  • D Block (Groups 3,-12)
  • P Block (Groups 13-18)
33
Q

How do you find the amount of electrons in each element in each orbital?

A
34
Q

What are the exceptions to the rule with electron config?

A
  • Unpaired electron spins are unbalanced
  • Producing a natural repulsion between electrons causing an untastable atom
  • In order to improve stability the arrangement of electrons will; change
35
Q

What is the definition of periodicity?

A

The physical, atomic and chemical properties within periods in the periodic table that repeats regularly

36
Q

What are the trends in periodicity?

A
  • As you go along a period
  • The ionic radius decreases
  • The number of protons increase
  • Increasing the nuclear charge
  • Increasing the forces of attraction between the nucleus and the outer electrons
  • Increasing ionisation energy
37
Q

What is the trend in ionisation energy across a period?

A
  • As you go along a period the first ionisation energy increases
  • Apart from group 2→3 and 5→6
38
Q

What is the trend in melting point across a period

A
  • An increase from group 1 to group 4
  • A sharp decrease and flatline from group 5 to group 8
    • Group 1 and 2 are giant lattice structures with metallic bonding
    • Group 3 and 4 are giant lattice structures with covalent bods
    • Groups 5 to 8 are simple covalent molecules with weak electrostatic forces of attraction

[OBSELETE] Edexcel - A Level Chem (27 decks)

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