Atomic Structure

Question 1

What name do we give to the type of attraction between the positive protons and negative electrons?

Answer 1

• electrostatic

Question 2

What is atomic number Z?

Answer 2

• amount of protons

Question 3

What is the mass number A?

Answer 3

• amount of protons + neutrons

Question 4

What is an isotope

Answer 4

• atoms of the same element with the same amount of protons but different amount of neutrons

Question 5

What is relative atomic mass (Ar)

Answer 5

• average mass of an atom of an element relative to 1/12th the mass of an atom of carbon-12

Question 6

What is relative molecular mass (Mr)

Answer 6

• average mass of a molecule of an element relative to 1/12th the mass of an atom of carbon-12

Question 7

What is isoelectronic

Answer 7

• same electronic configuration

Question 8

How does electron impact ionisation work?

Answer 8

• high energy electrons fired at vaporised sample
• one electron is knocked off forming an M+ ion

Question 9

How does electrospray ionisation work?

Answer 9

• the sample is dissolved in a volatile solvent and forced through the end of a hypodermic needle
• needle attacked to the positive terminal of a power supply
• particles gain a proton as they leave the needle forming a MH+ ion

Question 10

How are the particles accelerated?

Answer 10

• the positively charged species are attracted to a negatively charged accelerating plate

Question 11

Describe the process of detection

Answer 11

• the positive ions hit the detector plate and gains an electron
• this generates a current and the size of the current is proportional to the abundance of the ion

Question 12

What is a molecular ion

Answer 12

• the molecule with one electron knocked off
  OR
• the ion with the largest m/z (value/ratio)

Question 13

What is high resolution mass spectrometry?

Answer 13

• allows us to see the exact masses of isotopes if different elements

Question 14

Chemical bonds are always…

Answer 14

• bending
• stretching
• vibrating

Question 15

Every type of bond has its own…

Answer 15

• unique natural frequency that is in the infrared region of the EM spectrum

Question 16

What happens when infrared radiation is passed through a sample of a compound?

Answer 16

• certain frequencies are absorbed depending on the bonds which are present
• these frequencies are not detected and therefore we get peaks

Question 17

What does an acidic O-H bond look like?

Answer 17

• very broad peak between 2500-3000

Question 18

What does an O-H bond in alcohols look like

Answer 18

• broad peak between 3230-3550

Question 19

What does a C=O bond look like?

Answer 19

• long sharp peak between 1680=1750

Question 20

What is the fingerprint region?

Answer 20

• region of an infrared spectrum below 1500 - unique to every compound