chemistry paper 1 Flashcards
(29 cards)
Explain the trend in reactivity of group 1 elements
The elements get more reactive as you go down group 1 because:
As you go down the group the atoms get bigger as there are more electron shells (more shielding).
In the larger atoms the attraction between nucleus and outer electrons gets weaker.
Because of the weaker attraction the outer electron is more easily lost.
Explain the trend in reactivity of group 7 elements
The elements get less reactive as you go down group 7 because:
As you go down the group the atoms get bigger as there are more electron shells (more shielding).
In the larger atoms the attraction between nucleus and outer electrons gets weaker.
Therefore, it is harder to gain the extra electron.
Explain the trend in boiling points of group 7/0 elements
The melting/boiling points increase as you go down group 7/0.
This is because the atoms get bigger as there are more electron shells.
Bigger atoms have stronger intermolecular forces holding them together.
Therefore, more energy is required to overcome these forces.
Explain why group 0 are unreactive
When elements react, their atoms complete their outer shells by losing or gaining electrons.
The atoms in group 0 already have a full outer shell (most stable arrangement of electrons).
So therefore, they do not need to react.
Explain the findings of the alpha-scattering experiment
In the alpha-scattering experiment a beam of alpha particles was directed at a sheet of very thin gold.
Most alpha particles went straight through the foil, showing the atom is mostly empty space.
A small number were deflected at large angles, suggesting a concentration of positive charge in the nucleus.
Very few reflected straight back, showing mass and positive charge are concentrated at the centre.
Describe the differences between the plum pudding model and the nuclear model
The plum pudding model has a ball of positive charge with electrons randomly placed, no nucleus, and no neutrons.
The nuclear model has positive charges in the centre/nucleus, electrons in fixed positions, and includes neutrons in the nucleus.
Describe, in terms of electrons, the reaction between magnesium and chlorine
One atom of magnesium reacts with two atoms of chlorine (MgCl₂).
The magnesium atom loses 2 electrons to become a 2+ ion.
Each chlorine atom gains 1 electron to become a 1− ion.
Describe the conditions needed for ionic compounds to conduct electricity
Ionic compounds must be dissolved in water (aqueous) or molten.
This allows ions to move and carry charge.
Explain why solid ionic compounds do not conduct electricity
The ions are in a fixed position and cannot move or carry a charge.
Explain why chlorine has a low boiling point
Chlorine is a simple molecule with weak intermolecular forces.
These weak forces are easily broken and do not require much energy to overcome.
Describe the structure and properties of diamond
Diamond is a giant covalent structure.
Each carbon atom is bonded to four others with strong covalent bonds.
There are no free electrons.
Diamond is very hard and has a high melting point.
It does not conduct electricity.
Describe the structure and properties of graphite
Graphite has a giant covalent structure.
Each carbon atom forms three covalent bonds, creating layers with no covalent bonds between them.
Delocalised electrons between layers allow graphite to conduct electricity.
Describe the structure and properties of graphene
Graphene is a single layer of graphite with strong covalent bonds.
It has a very high melting point, is very strong, and conducts electricity well due to delocalised electrons.
Describe the structure and properties of fullerenes
Fullerenes are molecules of carbon with hollow shapes.
Examples include buckminsterfullerene (C₆₀) and nanotubes.
Nanotubes have high tensile strength and conduct electricity due to delocalised electrons.
C₆₀ can act as a lubricant or deliver drugs due to its spherical shape.
Explain why diamond is hard
Diamond has a giant covalent lattice where each carbon atom forms 4 strong covalent bonds.
These bonds require a lot of energy to break.
Explain why graphite is soft
Graphite forms layers of carbon atoms bonded to three others.
Weak forces between layers allow them to slide over each other.
Explain why graphite conducts electricity
Each carbon is bonded to 3 others, leaving delocalised electrons that can move and carry charge.
Explain why alloys are harder than pure metals
Alloys are mixtures of elements including metals. Different sized atoms distort layers, preventing easy sliding.
This makes alloys harder and stronger.
Explain why metals are good conductors of heat
Metals have a giant lattice with positive ions and delocalised electrons.
Strong attractions mean energy is easily transferred through vibrations and free electrons.
Explain why metals are good conductors of electricity
Metals have delocalised electrons that are free to move and carry charge throughout the whole structure.
What is a limiting reactant?
A limiting reactant is the chemical that is used up in a reaction.
Explain how pH depends on acid strength and concentration
pH depends on H⁺ ion concentration — higher H⁺ = lower pH.
Stronger acids ionise more in water = more H⁺ = lower pH.
Higher concentration = more acid per volume = lower pH.
Describe how pH is linked to H+ ion concentration
pH is a measure of H⁺ concentration.
More H⁺ means lower pH. Increasing H⁺ concentration by a factor of 10 lowers pH by 1.
