1 - Atomic Structure

Question 1

What is the definition of an atom?

Answer 1

Basic units of matter that exist on their own, made of protons, neutrons and electrons.

Question 2

What is the definition of an element?

Answer 2

Matter comprised of atoms which are the same, with the same number of protons.

Question 3

What is the definition of a compound?

Answer 3

A substance containing two or more different atoms in a fixed ratio that are chemically bonded, with consistent properties.

Question 4

What is the definition of a molecule?

Answer 4

A substance where two or more different or the same atoms are chemically bonded in a fixed ratio.

Question 5

What is the definition of an isotope?

Answer 5

Atoms of the same element with the same number of protons and a different number of neutrons.

Question 6

What is the relative atomic mass formula?

Answer 6

mean mass
/
1/12 mass of C12 atom

Question 7

What is the definition of a mixture?

Answer 7

A substance containing two or more elements, molecules or compounds that aren’t chemically bonded.

Question 8

What does a mass spectrometer do?

Answer 8

Determines the mass number and abundance of isotopes.

Question 9

What is abundance?

Answer 9

How common an isotope is.

Question 10

How does electron bombardment work?

Answer 10

Sample is vaporized so it is in gas form
High energy electrons are fired which knock off an electron from each particle to form 1+ ions.
The positive ions are attracted to the negative plate.
The knocked off electron goes to a positive plate.

Question 11

How does electrospray work?

Answer 11

Sample is dissolved in a volatile substance.
Sample is passed through a charged hypothermic needle.
The particles gain a proton to become a 1+ ion. (Mr increases by 1)
The positive ions are attracted to the negative plate.

Question 12

Explain acceleration stage of mass spectrometry. (2)

Answer 12

The particles are given the same amount of kinetic energy.
The ions enter a drift tube.

Question 13

Explain ion drift stage of mass spectrometry. (3)

Answer 13

The velocity depends on the mass (lightest drifts fastest).
The ions separate based off their different velocities.

Question 14

Explain the detection stage of mass spectrometry. (4)

Answer 14

The ion detector is a charged negative plate.
When the ions hit the plater they gain an electron, inducing a current.
The current is proportional to the abundance of ions hitting the plate.
A mass spectrum is produced showing the abundance of each ion relative to its mass.

Question 15

Why is the interior of the mass spectrometer a vacuum?

Answer 15

To prevent the ions from colliding with molecules in the air.

Question 16

What is the formula for kinetic energy?

Answer 16

1/2 x mass x (velocity)^2

Question 17

What is the formula for velocity?

Answer 17

distance/ time

Question 18

What is the formula for the mass of a single atom?

Answer 18

atomic mass
/
Avogadro’s number

Question 19

What is the formula for molar mass?

Answer 19

grams/ moles

Question 20

What is the definition of First Ionisation Energy?

Answer 20

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

Question 21

What is the definition of Second Ionisation Energy?

Answer 21

The amount of energy required to remove one mole of electrons from a 1+ ion, in gaseous state, to form a 2+ ion.

Question 22

Why is there an increase in ionisation energy when removing electrons from one element?

Answer 22

There is an increase in protons, with no change in shielding, so the increased charge means it requires more energy to remove the electron, due to the stronger electrostatic attraction.

Question 23

Why is there a general increase in first ionisation energy across a period?

Answer 23

Increase in nuclear charge , so greater electrostatic attraction therefore more energy is required to remove the valence electron.

Question 24

What do the big jumps (up) mean when looking at ionisation energy of one element?

Answer 24

A change in energy levels, due to a decrease in shielding.

Question 25

Why is there a general decrease in first ionisation energy going down a group?

Answer 25

The number of energy levels increase, so shielding increases, so the outer electron gets further away from the nucleus, decreasing the electrostatic attraction.

Question 26

What do the big jumps (down) when comparing first ionisation energies of elements signify?

Answer 26

There is a new group, as a new energy level, means shielding increases, so the electron is further away from the nucleus, meaning it is less strong attracted to the nucleus and easier to remove.

Question 27

How is atomic radii measured?

Answer 27

It is half the distance between the centres of a pair of atoms.

Question 28

What is the effect on the atomic radius as the number of protons increase?

Answer 28

The radius decreases as the extra charge pulls the electrons closer to the nucleus.

Question 29

What is an orbital?

Answer 29

A region in space where one is likely to find an electron.

Question 30

Name the 4 orbitals, their shape and what energy level they can be found from.

Answer 30

s - spherical - in every level
p - dumbbells - from energy level 2
d - from energy level 3
f - from energy level 4

Question 31

How many electrons can be found in an s orbital?

Answer 31

2

Question 32

How many electrons can be found in an p orbital?

Answer 32

6

Question 33

How many electrons can be found in an d orbital?

Answer 33

10

Question 34

How many electrons can be found in an f orbital?

Answer 34

14

Question 35

What are the four rules of orbitals?

Answer 35

1) Can’t determine the position and momentum of an electron at the same time.
2) Electrons enter at the lowest available energy level.
3) Two electrons per orbital, if they are opposite spin.
4) When in orbitals of equal energy electrons will try to remain unpaired.

Question 36

Why is there the 1st small dip when comparing first ionisation energies?

Answer 36

There is an increase in shielding due to a jump from one orbital to another.

Question 37

Why is there the 2nd small dip when comparing first ionisation energies?

Answer 37

The electrons start to get paired together in orbitals, as there is repulsion by the electrons its easier to remove the electron.