1.1 Atomic Structure

Question 1

What comes first 4s or 3d?

Answer 1

4s

Question 2

Why can electrons be promoted from 4s to 3d?

Answer 2

• To make a full 3d shell when 3d has 8 electrons, to make it more stable
• To make the electrons in 3d and 4s odd, so there is no electron repulsion, so 4s will promote one electron to 3d to make 3d have an odd number of electrons instead of even so it is more stable

Question 3

What does the atomic number represent?

Answer 3

Number of protons (thus the number of electrons)

Question 4

What does mass number represent?

Answer 4

Mass, but also number of protons and neutrons

Question 5

What is an isotope?

Answer 5

An atom with the same number of protons but different number of neutrons

Question 6

What knocks off electrons from atoms in mass spectrometry to make them ions?

Answer 6

Electron gun

Question 7

How are ions accelerated in mass spectrometry?

Answer 7

They are attracted towards a negatively charged plate at high speed (the speed they travel depends on mass, lighter ion=faster)

Question 8

How are accelerated ions deflected?

Answer 8

They travel through a magnetic field at right angles to the direction they are travelling so that they are bent round a corner towards a detector.

Question 9

How do we know what ions will successfully be bent around the corner?

Answer 9

It depends on m/z ratio (mass/charge). Heavier ions are deflected less than lighter ones. Ions with a more positive charge are deflected more than a weaker positive charge.

Question 10

How do we detect ions at the end of the mass spectrometer?

Answer 10

Detector has a negatively charged plate that will make a slight electrical current each time a positive ion hits it. The strength of the current is proportional to the abundance of the ion.

Question 11

What equation can be used to calculate Mr when given a mass spectra?

Answer 11

(Abundance X mass) / overall abundance(usually 100)=Mr

Question 12

Neon has 2 isotopes with mass of 20 and 22 with abundances of 90% and 10%, calculate neons Mr.

Answer 12

(90 X 20) + (10 X 22)
__________________ = 20.2g
100

Question 13

Define Ar.

Answer 13

Average mass of one atom of an element
_____________________________________ = Ar
1 twelfth of the mass of 12C

Question 14

Define Mr.

Answer 14

The average mass of one molecule of a compound
_____________________________________________ = Mr
1 twelfth of the mass of 12C

Question 15

How many electrons can the third she’ll hold?

Answer 15

18