Atmoic Structure

Question 0

What is relative is isotopic mass?

Answer 0

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

Question 1

What is relative atomic mass?

Answer 1

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

Question 2

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

Answer 2

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

Question 3

What is relative molecular mass?

Answer 3

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

Question 4

What is relative formula mass?

Answer 4

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

Question 5

What is an isotope?

Answer 5

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

Question 6

What is ionisation energy?

Answer 6

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

Question 7

Describe the electron structure

Answer 7

1s2 2s2 ….. 4s2 3d10 4p6

Question 8

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

Answer 8

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

Question 9

Why do transition metals ionise differently?

Answer 9

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

Question 10

How do we do the shorthand for electronic structures?

Answer 10

Use noble gases

Question 11

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

Answer 11

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

Question 12

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

Answer 12

X (g) —-> X (+) (g) + e-

Question 13

As we go down groups what happens to ionisation energies?

Answer 13

Decrease as…

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

Question 14

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

Answer 14

Increases as…

Greater nuclear charge
No change in shielding

Question 15

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

Answer 15

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

Question 16

Describe the process of mass spectrometry

Answer 16

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

Question 17

Put these in order in the mass spectrometry.

Acceleration, vaporisation, detection, ionisation, deflection

Answer 17

Vaporisation 
Ionisation 
Acceleration 
Deflection 
Detection

Question 18

Why is the magnetic field strength increased in mass spectrometry?

Answer 18

To detect all ions

Question 19

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

Answer 19

Ions with a lower mass: charge ratio

Question 20

What are the three orbital types?

Answer 20

S, p and d

Question 21

Give the relative mass of electrons protons and neutrons?

Answer 21

1/2000 , 1 , 1

Question 22

Give the relative charges of protons neutrons and electrons?

Answer 22

+1 , 0 and -1

Question 23

What is the mass number of an atom?

Answer 23

The bigger of the two numbers shows the relative atomic mass

Question 24

What is the atomic number of an atom?

Answer 24

Smaller number of the two shows the protons and electrons number

Question 25

What three things affect ionisation energies?

Answer 25

Distance from nucleus
Nuclear charge
Shielding

Question 26

What do we use a mass spectrometer to calculate?

Answer 26

Relative atomic mass

Relative molecular mass

Question 27

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

Mass:charge ratio. Abundance

24. 79
25. 10
26. 11

Answer 27

Ar = 24.3 (magnesium)