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Chemistry > (1) Atomic Structure > Flashcards

(1) Atomic Structure Flashcards

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1
Q

What is the mass and charge of Protons, Neutrons and Electrons?

A

Proton:

  • mass = 1
  • charge = +1

Neutron:

  • mass = 1
  • charge = 0

Electron:

  • mass = 1/1840
  • charge = -1
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2
Q

Define atomic number.

A

The atomic number is equal to the number of protons.

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3
Q

Define mass number.

A

The mass number is equal to the number of protons and neutrons combined.

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4
Q

Define relative atomic mass.

A

Average mass of 1 atom (of an element)
[divided by]
1/12 mass of one atom of 12C

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5
Q

What are isotopes?

A

Atoms with the same number of protons but a different number of neutrons.

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6
Q

Do isotopes of the same element have the same chemical properties and why?

A

Yes

Because they have the same electron configuration

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7
Q

Define First Ionisation Energy.

A

Energy when one mole of electrons is removed from one mole of gaseous atoms to form one mole of gaseous 1+ ions

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8
Q

Write an equation for the 1st Ionisation Energy for Potassium.

A

K(g) —> K+(g) + e-

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9
Q

Why is the 2nd Ionisation Energy of S higher than the 1st?

A

The second electron is removed from an ion that already has a positive charge.

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10
Q

What is the model answer for:

The following data shows the first seven successive ionisation energies of a period 3 element. State which element it is and explain your reasoning.

A

When approaching a question like this, look for where there are large gaps between the ionisation energies:

Model Answer:

  • The biggest jump is between the 4th and 5th ionisation energies
  • The 5th electron is on the shell closer to the nucleus
  • The element must have 4 electrons on its outer shell
  • In period 3 this must be silicon
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11
Q

What is the shape of:

  1. s orbital
  2. p orbital
A
  1. spherical

2. dumbbell

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12
Q

How many s orbitals are in the s subshell?

How many p orbitals are in the p subshell

How many d orbitals are in the d subshell?

A

1

3

5

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13
Q

Which orbitals have the lowest energy?

A

The ones closest to the nucleus.

Rule: The higher the orbital, the higher in energy it is.

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14
Q

Which electron on an atom is highest in energy?

A

The outer most electron - because it is the furthest away from the nucleus.

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15
Q

What does an energy level diagram look like?

A
  • each box represents an orbital - each hold 2 electrons
  • each electron is represented by a half arrow, one pointing up, other pointing down
  • the half arrows represent the electrons spinning in different directions
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16
Q

3 rules for how to allocate electrons to orbitals?

A
  1. Orbitals of lower energy are always filled first
  2. Atomic orbitals of the same energy fill singly before electrons pair up
  3. No orbital can have more than 2 electrons
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17
Q

Why is Sulfur a p-block element?

A

It’s highest energy electron is in the p subshell.

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18
Q

How do you work out the electronic configuration of an ion?

A

You remove the electrons from the highest energy orbitals in its normal electronic configuration

19
Q

Which orbital is lower in energy, 4s or 3d?

What must you remember with these 2 orbitals when writing electronic configuration?

A

4s

  • FIRST IN FIRST OUT
  • electrons fill 4s first, then 3d
  • electrons are removed from 4s first, then 3d
20
Q

Rule for writing d-block element configurations?

A

They are more stable when they have a full, or exactly half full sub shell.

21
Q

Electronic configuration for Chromium?

A

1s2 2s2 2p6 3s2 3p6 4s1 3d5

22
Q

Electronic configuration for Copper?

A

1s2 2s2 2p6 3s2 3p6 4s1 3d10

23
Q

Electronic configuration Cu2+?

A

1s2 2s2 2p6 3s2 3p6 3d9

24
Q

What is the general trend in Ionisation Energy across a period?

A
  • general increase across the period
  • this is because across period 3 there is a greater nuclear charge
  • same amount of shielding
  • so greater attraction between the nucleus and outer electron
25
Q

Explain why Aluminium has a lower 1st 1E than Magnesium.

A
  • The first e- removed from Mg is from a 3s sub level.
  • The first e- removed from Al is from a 3p sub level.
  • The 3s sub level is lower in energy than 3p.
  • Therefore less energy is needed to remove the electron from Al.
26
Q

Explain why Sulfur has a lower 1st IE than Phosphorous.

A
  • The first e- removed from P is from a 3p sub level and is unpaired.
  • The first e- removed from S is also from a 3p sub level, but is from a paired orbital.
  • This means Sulfur has a lower ionisation energy due to electron pair repulsion.
  • Therefore less energy is needed to remove the electron from S.
27
Q

Trend in Ionisation Energy down a Group?

A
  • atoms get bigger
  • more shielding
  • weaker attraction from nucleus to electron in outer shell
  • ionisation energy decreases down group
28
Q

State and explain the trend in Atomic Radius down a Group?

A

Atomic radius increases.

The number of shells increases so the amount of shielding increases.

There is a weaker attraction between the electrons and the nucleus.

29
Q

State and explain the trend in Atomic Radius across a Period.

A

Atomic radius decreases.

The nuclear charge increases.

The amount of shielding stays the same.

There is a greater attraction between the electrons and the nucleus.

30
Q

What two factors does Mass Spectrometer measure?

A

Measures:

  • relative abundance
  • mass/charge ratio
31
Q

Why is the entire machine in a vacuum?

A

To prevent any of the particles being tested colliding with molecules from the air.

32
Q

Describe Electron Impact, and give the equation.

A

High-energy electrons

Fired at sample

From an electron gun

Knock an electron off sample particles forming 1+ ions

X(g) —> X+(g) + e-

33
Q

Describe Electrospray Ionisation, and give the equation.

A

Sample is dissolved in a volatile solvent

Then injected through a fine hypodermic needle

Tip of needle is connected to positive terminal of high voltage

Sample particles gain a proton

X(g) + H+ —-> XH+ (g)

34
Q

Explain why it is necessary to ionise molecules when measuring their mass in a TOF Mass Spectrometer.

A

Ions will be accelerated by attraction to negative plate

Only ions will accept an electron and generate a current when hitting the detector

35
Q

How is the ion separated in the flight tube?

A

Ions travelling at higher speeds (small m/z)move ahead move ahead of those travelling more slowly (large m/z).

36
Q

How are the ions detected and how is their abundance measured?

A

Each ion hits the detector

Ion gains an electron

Generates a current

Size of the current is proportional to the abundance of the ion

37
Q

Referring to KE = 0.5 X M X V^2, what stays constant for all ions in the question?

A

The kinetic energy.

38
Q

How do you calculate the mass in kg of a ion?

A

Mass number divided by 1000, then divided by avagadros constant

39
Q

Boron has relative atomic mass of 10.8

Boron exists as two isotopes, 10B and 11B.

Calculate the percentage abundance of 10B in this naturally occurring sample of Boron.

A

20%.

40
Q

State two differences between the plum pudding model and the model of atomic structure used today.

A
  • New model has a nucleus containing protons and neutrons

- Electrons are now arranged in shells

41
Q

Sodium fluoride contains sodium ions (Na+) and fluoride ions (F-).

Na+ and F- have the same electron configuration.

Explain why a fluoride ion is larger than a sodium ion.

A

Fluoride has lower nuclear charge.

Weaker attraction between nucleus and outer electrons.

42
Q

Write an equation, including state symbols, to represent the process that occurs when the third ionisation energy of manganese is measured.

A

Mn2+ (g) ⟶ Mn3+ (g) + e−

43
Q

Chlorine exists as two isotopes 35Cl and 37Cl in the ratio 3:1

Which statement about peaks in the mass spectrum of Cl2 is correct?

A

Peaks at m/z = 70 and 74 in the ratio 3:1

B

Peaks at m/z = 70, 72 and 74 in the ratio 9:6:1

C

Peaks at m/z = 70, 72 and 74 in the ratio 9:3:1

D

Peaks at m/z = 70 and 72 in the ratio 3:1

A

B

Chemistry (29 decks)

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