Topic 1 - Atomic Structure and Periodic Table

Question 1

What are the relative masses and charges of the particles in an atom?

Answer 1

Proton: mass-1, charge-1
Neutron: mass-1, charge-0
Electron: mass:0, charge- -1

Question 2

Why are atoms said to be neutral?

Answer 2

Atoms have no overall charge because the charges cancel out. This is because the number of protons is equal to the number of electrons and neutrons have no charge.

Question 3

How do you work out the number of neutrons in an atom?

Answer 3

Mass number - Atomic Number = No. of neutrons

Question 4

What is an element?

What is an isotope?

Answer 4

An element is a substance made up of one type of atom.

An isotope is a different form of an element but with a different number of neutrons.

Question 5

How do you work out the relative atomic mass?

Answer 5

Relative atomic mass = sum of (isotope abundance*isotope number) / sum of abundance of all isotopes

Question 6

What is the difference between a compound and a mixture?

Answer 6

A compound is made up of different atoms chemically bonded together whereas a mixture is both elements and compounds not chemically combined so can easily be separated using physical techniques.

Question 7

What are the different separation techniques?

Answer 7

Chromatography
Filtration
Simple distillation
Fractional distillation
Evaporation
Crystallisation 

GO AND REFER TO THE PRACTICALS FOR THESE

Question 8

Describe the history of the atom.

Answer 8

John Dalton: solid spheres
JJ Thomson: ‘plum pudding model’- atom is positively charged with electrons
Rutherford: Gold foil- alpha particles went through, defelcted proved atom was mostly empty space and most of its mass was concentrated at the centre
Niels Bohr: electrons orbited in shells around the nucleus
James Chadwick: proved existence of neutrons

Question 9

How was the previous periodic table ordered?

Answer 9

In order of their properties and atomic weight

Question 10

Why did Mendeleev leave gaps in the periodic table?

Answer 10

For undiscovered elements to fit the group they should be in based on their properties

Question 11

What charges do metals and non-metals form?

Answer 11

Metals form positive ions. Non-metals form negative ions.

Question 12

What are some physical properties of a metal in comparison to a non-metal?

Answer 12

Metals:

• – high melting and boiling points
• – strong
• – good conductor of heat and electricity
• – malleable

Non-metals:

• – dull-looking
• – bad conductors of heat and electricity
• – brittle

Question 13

What are properties of transition metals?

Answer 13

Transition metals:

• – Form ions of different charges
• – Strong
• – High melting and boiling points
• – Good conductors of heat and electricity
• – Good catalysts
• – Form coloured compounds
• – High density

Question 14

Describe the trend in reactivity of group 1 metals.

Answer 14

As you go down the group, reactivity increases due to the fact that the outer shell electrons are further away from the nucleus meaning there is a weaker force of attraction. The weaker force of attraction means that the outer shell electron is more easily lost.

Question 15

Describe the trend in melting and boiling points of alkali metals.

Answer 15

As you go down group 1 metals, melting and boiling points decrease.

Question 16

Describe the reactivity of lithium, sodium and potassium with water

Answer 16

Lithium: fizzes, floats on surface, reduces in size till eventually disappears
Sodium: fizzes more vigorously than lithium, moves on surface of water
Potassium: lilac flame produced, fizzes more vigorously than sodium, moves rapidly on water surface

Question 17

Describe the trend in reactivity of the halogens

Answer 17

As you go down the group, reactivity decreases due to the fact that the outer shell is further from the nucleus. This means their is a weaker force of attraction between the outer shell electrons and the nucleus so it is harder to gain an electron.

Question 18

Describe the trend in melting and boiling points of group 7

Answer 18

As you go down the group, melting and boiling points increase. This is because the atom increases in size and there are greater intermolecular forces therefore more energy is required to break the bonds.

Question 19

What is the name of group 0 elements and why are they inert?

Answer 19

Group 0 elements are called the noble gases. They are inert (unreactive) due to the fact that they have a full outer shell so it is not possible for them to gain or lose and electron.