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AQA As Level Chemistry Unit One > Atmoic Structure > Flashcards

Flashcards in Atmoic Structure Deck (28)
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0
Q

What is relative is isotopic mass?

A

The mass of an atom of an isotope of an element on a scale where an atom of carbon 12 is exactly 12 units.

1
Q

What is relative atomic mass?

A

The average mass of an atom of an element on a scale where an atom of carbon 12 is exactly 12 units.

2
Q

Calculate the relative atomic mass of chlorine in a sample where 75% is CL 35 and 25% is CL 37

A

(75x35) + (25x37) / 100 = 35.5

3
Q

What is relative molecular mass?

A

Is average mass of a molecule on a scale where carbon 12 is exactly 12 units

4
Q

What is relative formula mass?

A

The average mass if a formula unit on a scale where carbon 12 is exactly 12 units.

5
Q

What is an isotope?

A

Atoms of an element with the same number of protons but a different number of neutrons

6
Q

What is ionisation energy?

A

The energy required to remove one mole of electrons from one mole of gaseous atoms

7
Q

Describe the electron structure

A

1s2 2s2 ….. 4s2 3d10 4p6

8
Q

Name two exceptions to the electron structure and why they are exceptions

A

Chromium (Cr) it’s structure is ….3d5 4s1 as 3d and 4s have similar energy levels is it fills all it’s orbitals to avoid repulsion

Cooper (cu) it’s structure is … 3d10 4s1 repulsion in a 3d orbital is less than a 4s orbital

9
Q

Why do transition metals ionise differently?

A

They lose their 4s electrons first when ionised as these have the most? energy and are easiest to remove

10
Q

How do we do the shorthand for electronic structures?

A

Use noble gases

11
Q

How does ionisation levels change as more electrons are removed from an atom?

A

The ionisation energy increases as….

The electron being removed is closer to the nucleus (greater electrostatic forces of attraction)
Same nuclear charge spread across fewer electrons
Less shielding

12
Q

Write an equation for the general first ionisation of an atom (using x)

A

X (g) —-> X (+) (g) + e-

13
Q

As we go down groups what happens to ionisation energies?

A

Decrease as…

Electron being removed is further from nucleus (less electrostatic attraction)
More shielding
Outweighs stronger nuclear charge

14
Q

What is the General trend in ionisation energies across a period?

A

Increases as…

Greater nuclear charge
No change in shielding

15
Q

Why are there two exceptions in the ionisation energies across periods?

A

1st drop - electron being removed from a p orbital (instead of s orbital) p orbitals are higher in energy than s orbitals so the electron being removed is further from the nucleus and therefore is easier to remove

2nd drop - two electrons must share a p orbital, they repel and so are easier to remove

16
Q

Describe the process of mass spectrometry

A
  1. Vaporisation - sample turned into a gas via an electrical heater
  2. Ionisation - bombarded with high energy electrons to ionise them - knocks electrons off atoms
  3. Acceleration - positive ions accelerated by an electric field
  4. Deflection - magnetic field strength increased to detect all ions
  5. As ions reach the detector a current is induced
17
Q

Put these in order in the mass spectrometry.

Acceleration, vaporisation, detection, ionisation, deflection

A
Vaporisation 
Ionisation 
Acceleration 
Deflection 
Detection
18
Q

Why is the magnetic field strength increased in mass spectrometry?

A

To detect all ions

19
Q

Which ions are deflected more in a mass spectrometer and why?

A

Ions with a lower mass: charge ratio

20
Q

What are the three orbital types?

A

S, p and d

21
Q

Give the relative mass of electrons protons and neutrons?

A

1/2000 , 1 , 1

22
Q

Give the relative charges of protons neutrons and electrons?

A

+1 , 0 and -1

23
Q

What is the mass number of an atom?

A

The bigger of the two numbers shows the relative atomic mass

24
Q

What is the atomic number of an atom?

A

Smaller number of the two shows the protons and electrons number

25
Q

What three things affect ionisation energies?

A

Distance from nucleus
Nuclear charge
Shielding

26
Q

What do we use a mass spectrometer to calculate?

A

Relative atomic mass

Relative molecular mass

27
Q

Calculate the relative atomic mass and name the element from this mass spectromer:

Mass:charge ratio. Abundance

  1. 79
  2. 10
  3. 11
A

Ar = 24.3 (magnesium)