C1

Question 1

How did JJ Thompson discover the electron?

Answer 1

• experimented with a cathode ray tube
• the beam moved towards the positively charged plate, so he knew the particles must be negative

Question 2

What are the three ideas Dalton had about the atom?

Answer 2

• cannot be created or destroyed
• all atoms of the same element are the same
• they join, to make new substances

Question 3

Describe Rutherford model of the atom

Answer 3

• mass is concentrated in centre
• mostly empty space
• electrons travel in random paths

Question 4

What is the radius of a nucleus, and how does it compare to the actual radius?

Answer 4

• nucleus radius = 1X10⁻¹⁴m
• it is 1/10000 of the atomic radius

Question 5

How did Mendeleev arrange the periodic table?

Answer 5

• elements arranged in order of increasing atomic mass
• elements with similar properties put in groups
• switched positions of some elements
• gaps left for undiscovered elements

Question 6

Why did Mendeleev’s table lack accuracy?

Answer 6

• isotopes were understood poorly
• protons and neutrons had not been discovered

Question 7

How are elements arranged in the modern periodic table?

Answer 7

Increasing atomic number

Question 8

What determines whether an element is a metal or non-metal?

Answer 8

The atomic structure they have

Question 9

What does it mean if the ionic compound ends in -ide?

Answer 9

The compound has 2 elements

Question 10

What does it mean if an ionic compound ends in -ate?

Answer 10

Compound contains three elements at least, including oxygen

Question 11

Describe the structure of an ionic compound

Answer 11

• lattice structure
• regular arrangements of ions
• ions held together by strong electrostatic forces between ions of opposite charge
• conduct when aqueous or molten, as charged particles are free to move

Question 12

Describe the structure of simple molecular compounds

Answer 12

• have weak intermolecular forces, but throng covalent bonds (low melting and boiling points)
• do not conduct as they are not charged particles

Question 13

What are the uses of graphite?

Answer 13

• electrodes (conducts and has a high melting point)
• lubricant (slippery)

Question 14

What is a fullerene?

Answer 14

A molecule made of carbon, shapes like a closed tube or hollow ball

Question 15

What are the properties of buckminsterfullerene (C₆₀)?

Answer 15

• slippery (weak intermolecular forces)
• low melting point
• strong covalent bonds between carbon
• large surface area

Question 16

What are the properties of the fullerene graphene?

Answer 16

• high melting point due to the covalent bonding
• conducts as there is delocalised electrons

Question 17

Why is graphene used in electronics?

Answer 17

• strong
• conducts (delocalised electrons)
• thin (only one atom)

Question 18

What are the properties of metals?

Answer 18

• high melting points
• high density
• good conductors
• malleable (atoms in rows, so can slide over each other) and ductile
• generally shiny

Question 19

What is the molecular formula?

Answer 19

Actual number of atoms of each element in a compound

Question 20

What equation links mass, moles, and relative atomic mass?

Answer 20

Mass (g) = moles (mol) X relative atomic mass (Mr)

Question 21

How do you calculate concentration in g/dm³?

Answer 21

Concentration (g/dm³) = mass (g) / volume (dm³)

Question 22

What is Avogadro’s constant?

Answer 22

• number of atoms, molecules or ions in one mole of any substance
• the value is 6.02 X 10²³

Question 23

What is a limiting reagent in a chemical reaction?

Answer 23

• chemical that is used up first in a reaction, preventing more product forming
• typically, an excess of one is used to make sure all of the other reacts