Topic 2: Atomic Structure and the Periodic Table

Question 1

What are the three subatomic particles in an atom ?

Answer 1

Protons
Neutrons
Electrons

Question 2

Describe the structure of an atom

Answer 2

• A small central nucleus made up of protons and neutrons (positively charged)
• Electrons orbit the nucleus in shells (negatively charged)

Question 3

Where is the mass of the atom concentrated?

Answer 3

In the nucleus

Question 4

What are the relative masses of a proton, neutron and electron?

Answer 4

Proton: 1
Neutron: 1 Electron: 1/1836

Question 5

What are the relative charges of a proton, neutron and electron?

Answer 5

Proton: +1
Neutron: 0
Electron: -1

Question 6

What does the atomic number tell you about an element?

Answer 6

The atomic number is unique to each element and tells you the number of protons an element has.

Question 7

What is the mass number?

Answer 7

The combined total of the number of protons and neutrons in an atom of an element.

Question 8

What are isotopes?

Answer 8

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

Question 9

How does the atomic number and mass number differ between isotopes of the same element?

Answer 9

Atomic number is the same as an element always has the same number of protons.
Mass number is different as there are different numbers of neutrons.

Question 10

Why do atoms contain equal numbers of protons and electrons?

Answer 10

Atoms have a stable overall charge of 0.
Protons are positively charged and electrons are negatively charged so they must be present in equal numbers for charges to balance.

Question 11

How can you calculate the number of neutrons, given the mass number and atomic number of an element?

Answer 11

Number of neutrons =

mass number - atomic number

Question 12

Boron has the atomic number 5 and mass number 11. How many protons, electrons and neutrons does boron have?

Answer 12

5 protons
5 electrons
6 neutrons

Question 13

Sodium has the atomic number 11 and mass number 23. How many protons, electrons and neutrons does the Na+ ion have?

Answer 13

11 protons
10 electrons (one has been lost to form the positive ion)
12 neutrons

Question 14

How can you use a mass spectrum to deduce the relative molecular mass of a sample of a compound?

Answer 14

The peak with the highest m/z value (the molecular ion peak, M+) is caused by the whole molecule, therefore that m/z value = molecular mass.

Question 15

‘Ions in a mass spectrometer can have a 2+ charge’

True or False?

Answer 15

TRUE

Ions in a mass spectrometer can have a 2+ charge, but the 1+ charge is more common.

Question 16

What is first ionisation energy?

Answer 16

First ionisation energy is the energy required to remove one electron from from one mole of gaseous atoms to form one mole of gaseous ions.

Question 17

What is second ionisation energy?

Answer 17

Second ionisation energy is the energy required to remove one electron from from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.

Question 18

Is ionisation energy exothermic or endothermic?

Answer 18

Endothermic

Question 19

What factors influence ionisation energy?

Answer 19

● The number of protons in the nucleus
● The subshell from which the electron is removed
● Electron shielding

Question 20

How do successive ionisation energies tell you which group an element belongs to?

Answer 20

A large increase between two different successive ionisation energies i.e. between 7th and 8th ionisation energy suggests the 8th electron is being taken from a new, full, stable shell (and hence this requires more energy to remove).
There is therefore 7 electrons in its outer shell so the element belongs to group 7.

Question 21

What does first ionisation energy of successive elements provide evidence for?

Answer 21

Electron subshells.

Question 22

What do s and p orbitals look like?

Answer 22

spherical

dumbell