Topic 2

Question 1

Isotopes definition

Answer 1

atoms of the same element that have the same amount of protons but differ in the amount of neutrons

Question 2

do isotopes have the same physical or chem properties?

Answer 2

have the same chem properties, have different physical properties

Question 3

Why do isotopes have the same chemical properties?

Answer 3

because they have the same number of electrons, this means they take part in the exact same chemical reactions

Question 4

Why do isotopes have different physical properties?

Answer 4

because their mass number is different, melting and boiling points can be different

Question 5

define nucleon

Answer 5

a particle in the nucleus e.g proton/neutron

Question 6

define atomic number

Answer 6

number of protons found in the nucleus of an element

Question 7

define atomic mass

Answer 7

number of protons & neutrons n the nucleus of an element

Question 8

What happens when an electron returns to its previous energy level?

Answer 8

the energy that was absorbed is lost through emission
this energy is released in the form of photons
the frequency, wavelength & colour of light all depend on the element & the amount of energy lost
- the highest possible fall in energy produces the highest frequency

Question 9

What does the line spectrum of hydrogen show?

Answer 9

the different series of lines that converge at high energy

• the lines correspond to transitions ending at the same energy level
• when lines converge, the frequency increases, the higher the frequency, the higher the energy is of light

Question 10

Lyman series

Answer 10

series of lines in the UV

Question 11

Balmer series

Answer 11

visible light

Question 12

Paschen series

Answer 12

IR light

Question 13

What are the factors that effect ionisation energy?

Answer 13

• size of the atom

- nuclear charge

Question 14

How does size of the atom affect ionisation energy?

Answer 14

as number of shells increases, the outer electrons will become further away from the nucleus and will need less energy to remove the electron, therefore ionisation energy will decrease

Question 15

How does nuclear charge affect ionisation energy?

Answer 15

as nuclear charge increases, the outer electrons will be attracted more to the nucleus, therefore they need more energy to be removed & the ionisation energy will decrease

Question 16

what does n=1 refer to?

Answer 16

the ground state

Question 17

what is n ?

Answer 17

the principle quantum number which denotes the principle energy level

Question 18

Energy levels

Answer 18

• can hold a max of 2 electrons
• each energy level is divided into 2 sub energy levels
• lowest energy level is the most stable & closest to the nucleus

Question 19

Which energy level is the most stable?

Answer 19

the lowest one, because it is closest to the nucleus

the energy level closest to the nucleus have the lowest amounts in energy

Question 20

What are the sub-energy levels?

Answer 20

s,p,d & f

Question 21

S

Answer 21

lowest energy, can hold 2 electrons

Question 22

F

Answer 22

highest energy, can hold 14 electrons

Question 23

how many orbitals does S have?

Answer 23

1 orbital

Question 24

how many orbitals does p have?

Answer 24

3 orbitals

Question 25

how many orbitals does d have?

Answer 25

10 orbitals

Question 26

how many orbitals does f have?

Answer 26

14 orbitals

Question 27

How do electrons fill up orbitals?

Answer 27

in order of increasing energy levels

Question 28

What do the boxes represent?

Answer 28

orbitals

Question 29

What do the arrows in the boxes represent?

Answer 29

the spin of the electrons

Question 30

What is the aufbau principle?

Answer 30

• electrons must always occupy the lowest energy levels first
• the 1s sub-level has the lowest energy, therefore it is filled up first
• the 4s sub-level fills before the 3d sub-level

Question 31

What are the exceptions to the Aufbau principle?

Answer 31

• chromium

- copper

Question 32

What is Hund’s rule?

Answer 32

• when assigning electrons to orbitals of the same energy, keep the electrons unpaired as much as possible
• electrons fill orbitals singularly before filling them in pairs

Question 33

What is Pauli’s exclusion principle?

Answer 33

2 electrons cannot have the same quantum number

- only 2 electrons fit inside each orbital & must have opposite spins

Question 34

Define relative atomic mass

Answer 34

the weighed mean of all the naturally occurring isotopes of an element on a scale relative to carbon-12

Question 35

Why on a scale relative to carbon-12?

Answer 35

carbon-12 is less expensive, easy to be isolated, easy to be purified, available & non-toxic

Question 36

Distinguish between a continuous spectrum & a line spectrum

Question 37

Explain why the relative atomic mass of cobalt is greater than the relative atomic mass of nickel, even though the atomic number of nickel is greater than the atomic number of cobalt.

Question 38

Identify a radioactive isotope of cobalt and state one of its uses.

Question 39

Explain what the square brackets around argon, [Ar], represent.

Question 40

Explain the large increase between the tenth and eleventh ionization energies.

Question 41

Which of the following can be deduced from the emission line spectrum of an element?

a. The existence of a dense nucleus in an atom
b. The existence of discrete energy levels in an atom
c. The existence of isotopes of an element
d. The existence of protons in the nucleus of an atom

Answer 41

The existence of discrete energy levels in an atom
- An emission line spectrum shows only certain wavelengths of light emitted by an element. This provides evidence for the existence of energy levels within the atom as only certain energies, or wavelengths, of light are emitted. The wavelengths of light emitted depend on the energy difference between the energy levels in the atom.

Question 42

Determine the maximum number of electrons that can be held in the d sub-level.

Answer 42

10