Atomic Structure and the periodic table

Question 1

what is the mass of an electron

Answer 1

1/1840

Question 2

atomic number (proton number) definition

Answer 2

number of protons in the nucleus of an atom of that element

Question 3

do isotopes have the same/similar chemical properties and why

Answer 3

they do because isotopes of the same element all have the same arrangement and number of electrons

Question 4

what determines chemical properties on an element

Answer 4

the arrangement and number of electrons

Question 5

isotope definition

Answer 5

atoms of the same element with the same number of protons but a different number of neutrons

Question 6

what is 1 mass unit equal to

Answer 6

1/12 the mass of a carbon-12 atom

Question 7

relative isotopic mass definition

Answer 7

the mass of an atom of an isotope divided by 1/12 the mass of a carbon-12 atom

Question 8

symbol for relative atomic mass

Answer 8

Ar

Question 9

relative atomic mass definition

Answer 9

the weighted average mass of an atom of an element divided by 1/12 the mass of a carbon-12 atom

Question 10

how to calculate r.a.m of 75% chlorine-35 and 25% chlorine-37

Answer 10

two isotopic forms of chlorine. 75% chlorine-35, 25% chlorine-37

sum of relative isotopic abundance (75+35)

Question 11

75% chlorine-35, what is the isotopic abundance in this

Answer 11

75%

Question 12

what technique measures abundances of different isotopes

Answer 12

mass spectrometry

Question 13

name the four stages of mass spectrometry

Answer 13

ionisation, acceleration, deflection, detection

Question 14

describe the ionisation (first) stage of mass spectrometry

Answer 14

(the sample is first vaporised, separating the atoms or molecules)
- stream of high energy electrons fired at sample
- energy from electrons strip electrons off the atoms or molecules
- positive ions formed

Question 15

what is the general equation for the ionisation stage of mass spectrometry

Answer 15

X(g) + e- -> X+ (g) + 2e-

Question 16

describe the acceleration (second) stage of mass spectrometry

Answer 16

• positive ions pass through an electric field
• this accelerates them into the instrument

Question 17

describe the deflection (third) stage of mass spectrometry

Answer 17

• the ions pass through a magnetic field
• are then deflected according to their mass and charge

Question 18

which type of ions will be deflected the most

Answer 18

those that are lighter and with a greater positive charge are deflected more

Question 19

describe the detection (fourth) stage of mass spectrometry

Answer 19

• beam of ions passing through the machine are detected electrically by an ion detector

Question 20

uses of mass spectrometry (3)

Answer 20

• to find mass of molecule
• carbon dating
• to find what is in a molecule

Question 21

what is the relative molecular mass

Answer 21

the average mass of a molecule of that element or compound divided by 1/12 the mass of a carbon-12 atom

Question 22

define the relative formula mass

Answer 22

average mass of a formula unit divided by 1/12 the mass of a carbon-12 atom

Question 23

what is the name of the peak with the highest m/z on the mass spectrum graph and what does it show

Answer 23

• molecular ion peak
• relative formula mass/molecular mass of the molecule

Question 24

why are there some lines to the left of the molecular ion peak on a mass spectrum graph

Answer 24

they are due to fragment ions which arise from some molecules breaking down