CH1 Atomic Structure

Question 1

Letter used to represent atomic number

Answer 1

Z

Question 2

What does atomic number indicate

Answer 2

Number of protons

Question 3

Letter used to represent mass number

Answer 3

A

Question 4

How is mass number calculated

Answer 4

Number of protons + Number of neutrons

Question 5

Definition of 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

Answer 6

Different forms of the same element. Containing same number of protons but different number of neutrons

Question 7

How many orbitals and electrons do these shells contain:

1s, 2p, 3s, 3d, 4s

Answer 7

1s - 1 orbital, 2 electrons
2p - 3 orbitals, 6 electrons
3s - 1 orbital, 2 electrons
3d - 5 orbitals, 10 electrons
4s - 1 orbital, 2 electrons

Question 8

Which has higher energy: 3d or 4s

Answer 8

3d

Question 9

Definition of orbital

Answer 9

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

Question 10

Relationship between 2 electrons in same orbital in terms of their spin

Answer 10

Have opposite spin as they repel each other

Question 11

Why does chromium not fit trend for electronic configuration

Answer 11

Only has 1 electron in 4s orbital before filling 3d orbital

Question 12

Why does copper not fit trend for electron configuration

Answer 12

Only has 1 electron in 4s orbital before filling 3d orbital

Question 13

What is electron impact ionisation

Answer 13

Electron gun knocks off one electron from each particle to form a +1 ion

Question 14

What is electrospray ionisation

Answer 14

Sample dissolved in volatile solvent and injected through a hollow hypodermic needle to give an aerosol. The needle is attached to a positive terminal of a high-voltage power supplu and particles gain a proton forming a + ion

Question 15

When is electron impact ionisation used

Answer 15

For organic and inorganic molecules with a low formula mass

Question 16

When is elcetrospray ionisation used

Answer 16

For substances with a higher molecular mass including biological molecules

Question 17

How time of flight mass spectrometer works

Answer 17

Acceleration - Positive ions attracted towards negatively charged plate
Ion drift - ions pass throug hole in plate, form a beam with constant kinetic energy, travel along tube to detector, therefore time of flight is directly proportional to square root of mass
Detection - positive ions pick up electrons, current flows, m/z value and time of flight recorded. Largest current from most abundant ions

Question 18

Define first ionisation energy

Answer 18

Energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions