Chapter 1 - atomic structure

Question 0

What are the relative masses of protons, electrons and neutrons?

Answer 0

proton - 1
neutron - 1
electron - 1/1840

Question 1

Define the term relative molecular mass

Answer 1

The average mass of an atom of an element compared to 1/12 the mass of a carbon-12 atom

Question 2

What are the relative charges of protons electrons and neutrons

Answer 2

proton - +1
neutron - 0
electron - -1

Question 3

Define the term isotope

Answer 3

Forms of an atoms containing the same number of protons but varying numbers of neutrons in the nucleus
Identical atomic numbers, different mass

Question 4

What did the gold-leaf experiment reveal?

Answer 4

The nucleus is very small, it has a positive charge, most of the atom is empty space

Question 5

What did the orbital theory suggest?

Answer 5

There are sub-shells in electron configuration,

assigning varying amounts of energy to electrons within the shell, defining the volume to where the electron exists

Question 6

Explain how Cl-35 and Cl-37 should react, explain why

Answer 6

Chemical properties of an atom are determined by electron configuration and isotopes of the same element have identical electron configurations therefore they react identically

Question 7

What order are electrons removed from an atom?

Answer 7

From highest energy to lowest, except 4s removed before 3d

Question 8

What are the 4 main stages of a mass spectrometer?

Answer 8

Ionisation, acceleration, deflection, detection

Question 9

What state does the sample need to be in the ionisation chamber?

Answer 9

Gaseous!

Question 10

What happens in the ionisation chamber?

Answer 10

High velocity electrons are fired from the electron gun to the gaseous atom to knock off 1 (or more) electrons to form cations

Question 11

What happens during acceleration?

Answer 11

positive ions are electrostatically attracted to the negatively charged plates and speed up; the speed they reach depends on their mass

Question 12

What happens during deflection?

Answer 12

Heavier ions are deflected less than lighter ones/doubly charged, the magnetic field gradually increases, the stronger the magnetic field, the greater the deflection

Question 13

What happens during detection?

Answer 13

Cations are deflected on the detector according to their mass, ions hit the detector, they accept electrons from the (metal) plate generating a small electrical current proportional to their abundance

Question 14

Why is their a vacuum in a mass spectrometer?

Answer 14

So theres no collisions of ions and the atoms in the air

Question 15

How do you calculate atomic mass?

Answer 15

(mass of isotoperelative abundance)+(mass of isotoperelative abundance)…

Question 16

Results from a mass spectrometer can be plotted on a graph, how should the graph be labelled?

Answer 16

y axis - abundance, x axis - m/z ratio

Question 17

When calculating atomic mass what do you need to remember?

Answer 17

To convert percentages into decimals

Question 18

What electrons have the most energy?

Answer 18

The outermost

Question 19

Cl2 has 3 ionised molecules: m/z at 70/72/74, explain why 72 is most common

Answer 19

Cl35-Cl37 or Cl37-Cl35 is twice as common as Cl35-Cl35 or Cl37-Cl37

Question 20

If abundance isn’t a percentage what should you do?

Answer 20

Do it as a fraction over the total

Question 21

What is the orbital electron configuration of krypton?

Answer 21

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

Question 22

what is the 1st ionisation of X? Including state symbols

Answer 22

X(g) –> X+(g) +e-

Question 23

What is the 2nd ionisation of X? Including state symbols

Answer 23

X+(g) –> X2+(g) + e-

Question 24

What do 2 electrons in the same orbital have and do?

Answer 24

Opposite spin and they repel

Question 25

Define the term ionisation energy

Answer 25

The energy required to remove a mole of electrons from a mole of atoms in the gaseous state in kJ/mol

Question 26

Define the term successive ionisation energy

Answer 26

The increasing amount of energy needed to remove electrons from ions

Question 27

Describe the general trend in ionisation energy across a period

Answer 27

Increases: Theres progressively more protons pulling on the same number of shells of electrons

Question 28

Describe the trend in the first ionisation energy down a group

Answer 28

Decreases: The outermost electrons, which are removed, are further from the nucleus so the pull isn’t as strong
Theres inner electron shell shielding the outermost electrons from the positive charge of the nucleus

Question 29

Outline what the anomalies are in period 3 first ionisation energy

Answer 29

Sulphur and aluminium

Question 30

Explain why the first ionisation energy dips at aluminium

Answer 30

Aluminium has an electron in the 3p orbital which is in slightly higher energy than the 3s therefore less energy is needed to remove it

Question 31

Explain why the first ionisation energy dips and silicon

Answer 31

Silicon has 2 electrons in the same orbital (3p4), the electrons repel slightly making it easier to remove an electron

Question 32

Explain why ionisation is endothermic

Answer 32

Energy is taken in to overcome the electrons electrostatic attraction to the nucleus

Question 33

Define the term atomic number

Answer 33

The number of protons in the nucleus

Question 34

Define the term mass number

Answer 34

The number of protons and neutrons in the nucleus