Things from the spec i didn't know

Question 1

How did Niels Bohr adapt the nuclear model?

Answer 1

Suggested that electrons orbit the nucleus at specific distance (energy levels)

Question 2

How was Bohr’s theory accepted?

Answer 2

His theoretical calculations agreed with experimental observations

Question 3

How big is the radius of an atom?

Answer 3

(1 x 10 ^ -10 m)

Question 4

What is the relative atomic mass of an element?

Answer 4

Average value of atomic mass that takes into account the abundance of all the isotopes of an element

Question 5

Why is it called the periodic table?

Answer 5

Similar properties occur at regular intervals

Question 6

What did knowledge of isotopes allow scientists to explain about the periodic table?

Answer 6

Knowledge of isotopes made it possible to explain why the order based on atomic weights was not always correct.

Question 7

Describe the alkali metals’ reactions with oxygen

Answer 7

Form metal oxides, reactivity increases down the group with faster more vigorous reactions

Question 8

Describe the alkali metals’ reactions with chlorine

Answer 8

Form metal chlorides, all of which are white solids that dissolve in water to make a colourless solution

Question 9

What do the alkali metals react with water to produce?

Answer 9

Metal hydroxides and hydrogen gas

Question 10

What is observed when lithium reacts with water?

Answer 10

Floats and moves slowly on surface of water
Bubbles of hydrogen form
Metal slowly dissolves

Question 11

What is observed when sodium reacts with water?

Answer 11

Melts into shiny, silvery ball due to heat released
Moves quickly across water surface
Bubbles vigorously, fizzes

Question 12

What is observed when potassium reacts with water?

Answer 12

Ignites with lilac flame as hydrogen catches fire
Moves rapidly, crackles
Heat generated can cause explosion of metal

Question 13

Describe the compounds made when a halogen reacts with a metal

Answer 13

Ionic halide
For white or colourless crystal solids
High melting and boiling points
Soluble in water (form electrolytes)

Question 14

Describe the compounds made when a halogen reacts with a non-metal

Answer 14

Covalent halides
Typically gases, liquids or low melting solids
Poor electrical conductors in any state
Distinctive colours or odours

Question 15

Why do the halogens have increasing melting and boiling points down the group?

Answer 15

Atoms get bigger, so stronger intermolecular bonds occur, so more energy required to break them apart

Question 16

Physical properties of transition metals

Answer 16

(compared with G1)
High melting points, densities, hard and strong

Question 17

Chemical properties of transition metals

Answer 17

(compared with G1)
React slowly with oxygen, generally unreactive with water, form a wide range of stable halides

Question 18

What are transition metals useful as + other typical properties?

Answer 18

Used as catalysts, form coloured compounds, have ions with different charges

Question 19

Describe the FoA in ionic bonding

Answer 19

Strong electrostatic forces of attraction between oppositely charged ions

Question 20

Describe the FoA in covalent bonding

Answer 20

Strong electrostatic forces of attraction between positively charged nuclei of two atoms and shared pair of electrons

Question 21

Describe the FoA in metallic bonding

Answer 21

Strong electrostatic forces of attraction between lattice of positive metal ions and sea of delocalised electrons

Question 22

In giant covalent structures, what type of bonds must be overcome to melt or boil the substances?

Answer 22

The strong covalent bonds that all of the atoms in the structure are linked to each other by

Question 23

What are carbon nanotubes?

Answer 23

Cylindrical fullerenes with very high length to diameter ratio

Question 24

How big are nanoparticles?

Answer 24

Diameter between 100 and 2500 nm, structures of around a few hundred atoms

Question 25

Disadvantages of nanoparticles?

Answer 25

Health risks (can be toxic), environmental impact, long term side effects unknown

Question 26

Why might it not be possible to obtain the calculated amount of a product?

Answer 26

The reaction may not go to completion because it is reversible Some of the product may be lost when separated from the reaction mixture Some of the reactants may react in ways different to the expected reaction

Question 27

What is the volume of one mole of any gas at room temp?

Answer 27

24dm^3

Question 28

The reactivity of a metal with water or dilute acids depends on what?

Answer 28

How easily it loses electrons to form its positive ion

Question 29

Why is carbon used as the anode in electrolysis of aluminium oxide

Answer 29

Good conductor and can withstand high temperatures

Question 30

Is cryolite a catalyst?

Answer 30

NO - it does not provide an alternative reaction pathway with a lower activation energy, and it gradually breaks down. It acts more like a solvent to lower the melting point of AlO2 - physical function not chemical

Question 31

What is the half equation for the cathode when hydrogen ions are reduced?

Answer 31

2H+ + 2e- → H2

Question 32

What is the half equation for the anode when hydroxide ions are oxidised?

Answer 32

4OH- → O2 + 2H2O + 4e-

Question 33

The half-equation at the cathode during the electrolysis of aluminium oxide?

Answer 33

Al3+ + 3e− → Al

Question 34

The half-equation at the anode during the electrolysis of aluminium oxide?

Answer 34

2O2− → O2 + 4e−

Question 35

Balanced equation for aluminium oxide electrolysis?

Answer 35

2Al2O3 → 4Al + 3O2 ​

Question 36

Why can some cells and batteries be recharged?

Answer 36

Rechargeable cells and batteries can be recharged because the chemical reactions can be reversed when an external electrical current is supplied.

Question 37

What is the half equation for a hydrogen fuel cell's anode?

Answer 37

H2 → 2H+ + 2e−

Question 38

What is the half equation for a hydrogen fuel cell's cathode?

Answer 38

O2 + 4H+ + 4e− → 2H2O