1.1 - Atomic Structure

Question 1

Which letter is used to represent the atomic number of an atom?

Answer 1

Z

Question 2

What does the atomic number tell us about an atom?

Answer 2

Atomic number equals number of protons in an atom

Question 3

What letter represents mass number?

Answer 3

A

Question 4

How is the mass number calculated?

Answer 4

Mass number = number of protons + number of neutrons

Question 5

Define relative atomic mass

Answer 5

Average mass of all isotopes of an element compared to 1/12 the mass of an atom of carbon 12

Question 6

What are isotopes of an element?

Answer 6

Different forms of the same element contain the same number of protons, but different number of neutrons. They still have the same chemical properties.

Question 7

Does 3d or 4s have a higher energy?

Answer 7

3D

Question 8

What is an orbital?

Answer 8

A region around the nucleus that can hold up to 2 electrons

Question 9

What would be the relationship between two electrons in the same orbital in terms of the spin?

Answer 9

Have opposite spin is repel each other as both negative

Question 10

Explain why chromium does not fit the trend for electronic configuration

Answer 10

It only has one electron in its 4s orbital before filling 3d

Question 11

Explain why copper does not fit the trend for electronic configuration

Answer 11

It only has one electron in its 4s orbital before filling 3d

Question 12

What are the two types of ionisation for a mass spectrometer? How do they differ? I’m

Answer 12

1. Electron impact electron gun knocks off one electron from each particle. To form 1+ molecular ions
2. Electrospray sample dissolved in volatile solvent and injected through a fine hypodermic needle to give an aerosol needle attached. A positive terminal of high voltage power supply and particles gain proton from the solvent as they leave the needle producing H+ ions.

Question 13

When would you use the different types of ionisation in mass spectrometry?

Answer 13

Electron impact used for organic or inorganic molecules with a low formula.
Mass electrospray used for substances with a high molecular mass, including biological molecules e.g. proteins

Question 14

Describe how a timer flight mass spectrometer works

Answer 14

Positive ions attracted towards the negatively charged plate.

Accelerate ions pass through hole in plate, form a beam with constant kinetic energy, travel along tube to detector. Time of flight is therefore directly proportional to the square root of mass.

positive ions pick up electrons current flows M/Z value and time of flight recorded largest current from most abundant ions

Question 15

Define first ionisation energy

Answer 15

The energy required to remove one mole of electrons from one mole of gaseous, atoms to form one mole of gaseous 1+ ions