Bridge Course

Question 1

Give two ways in which the plum pudding model differs from the current model

Answer 1

PROTONS and NEUTRONS in the nucleus
ELECTRONS in SHELLS

Question 2

Describe the experimental evidence that shows the plum pudding model is incorrect

Answer 2

Most alpha particles passed straight through - most of atom is empty space
Some particles were deflected - there is a small positively charged nucleus

Question 3

Give the relative masses and relative charges of each fundamental particle

Answer 3

Proton 1 +1
Neutron 1 0
Electron 1/1840 -1

Question 4

What is the atomic number

Answer 4

Number of protons in the nucleus

Question 5

What is the mass number

Answer 5

The number of protons and neutrons

Question 6

How do you calculate the number of neutrons

Answer 6

mass no - atomic number

Question 7

What is a cation and an anion

Answer 7

Cation - positive ion
Anion - negative ion

Question 8

Why does the reactivity increase down Group 1 of the periodic table

Answer 8

As electron number increases down the group, atomic radius increases, meaning more shielding
Attraction between the nucleus and outer electron weakens
Meaning less energy is needed to remove the outer electron

Question 9

What is an isotope

Answer 9

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

Question 10

Do isotopes of the same element have the same or different CHEMICAL properties. why

Answer 10

Same chemical properties because they have the same number of electrons

Question 11

Which physical properties of isotopes of the same element might be different

Answer 11

Mass, density, boiling points

Question 12

What is the relative isotopic mass

Answer 12

The mass of an isotope compared with 1/12th of an atom of carbon-12

Question 13

What is relative atomic mass

Answer 13

The weighted mean mass of an atom compared with 1/12th mass of an atom of carbon-12

Question 14

Give all the diatomic substances

Answer 14

Hydrogen, nitrogen, fluorine, oxygen, iodine, chlorine and bromine

Question 15

How do you calculate the empirical formula of a poly atomic molecule

Answer 15

• Make a column for each element
• Write the mass/percentage and divide by element’s Ar
• Divide all the answers by the smallest answer
• Find the simplest whole number ratio
• Write the empirical ratio

Question 16

How do you calculate molecular formula from the empirical formula

Answer 16

• Find empirical formula
• Work out mass of empirical formula
• Divide Mr by empirical mass
• Multiply empirical formula by this answer
• Write molecular formula

Question 17

How do you calculate the “water of crystallisation”?

Answer 17

1) Calculate the mass of the anhydrous salt: mass of crucible and residue - mass of crucible
2) Calculate the mass of water lost: mass of crucible and hydrated salt - mass of crucible and residue
3) Determine the ratio of anhydrous salt : water - write the mass of anhydrous salt and water and divide by their Mr ‘s - divide all answers by smallest answer

Question 18

Do atoms of elements in group 4 tend to form ions? Why

Answer 18

No, they would have to either lose 4 electrons or gain 4 electrons.

Question 19

Where in the periodic table are most elements able to lose different numbers of electrons.

Answer 19

• Central block of the periodic table, how many electrons an element can lose depends on what they are bonding to and what the environment is.
• These ions will have a roman numeral after the name e.g. nickel (II). The Roman numeral tells us the positive charge on the ion

Question 20

How can you work out ionic formulae from the name of the compound

Answer 20

• Looking at the charge on both the cation and anion and using multiples so these positive and negative charges cancel out

Question 21

Give the name and formula (with charge) of all the polyatomic ions

Answer 21

• Ammonium: NH4+
• Hydroxide: OH-
• Nitrate (V): NO3-
• Carbonate: CO3 2-
• Sulphate (VI): SO4 2-
  The last three end in ate meaning it’s an anion with oxygens

Question 22

How do you work out covalent formula

Answer 22

• Atoms that bond covalently don’t have charges: meaning we have to look at their names to give clues to formula
  Mono: 1
  Di: 2
  Tri: 3
  Tetra: 4
  Penta: 5
  Hexa: 6

Question 23

Can you use halves to balance an equation?

Answer 23

• Yes, only if they are in front of a diatomic molecule

Question 24

What order should you balance an equation in?

Answer 24

• Balance metals first
• Then non metals apart from H and O
• Then balance H and O

Question 25

What is the practical method for determining the formula of a hydrated salt?

Answer 25

Apparatus:
- Crucible and lid
- Bunsen
- Heat proof mat
- Tripod
- Clay-pipe triangle
- Tongs
- Access to a top pan balance
Method:
- Weigh a crucible and its lid on a top pan balance. Record its mass.
- Using a spatula, add roughly 3 scoops of hydrated salt to the crucible and re weigh. Record the mass.
- Heat the crucible over a blue Bunsen flame for approximately 5 minutes. Remove the lid of the crucible at regular intervals to allow water to evaporate
- Let it cool on a heatproof mat before reweighing. Record the mass.
- Heat the crucible again for a further 5 minutes. Repeat step 4.
- Repeat steps 3 and 4 until a constant mass has been achieved.