chemistry breadth mock Flashcards
Does the melting and boiling points of the noble gases increase or decrease as you move down the group?
Increase
Why do the melting and boiling points of the noble gases increase as you move down the group?
There’s an increase in the number of electrons in each atom leading to greater forces between the atoms which need to be overcome
As you go down group 7, do the halogens became less or more reactive?
Less
As you go down group 7, why do the halogens’ reactivities decrease?
It gets harder to attract the extra electron to fill the outer shell when its further away from the nucelus - the atom radius is larger
Describe the electron configuration of noble gases (elements in group 8/0)
All have eight electrons in their outer energy level, apart from helium which gas two, giving them a full outer shell. As their outer shell is energetically stable they don’t need to give up or gain electrons to become more stable
Describe the reactivity of noble gases (elements in group 8/0) and why
As they don’t need to give up or gain electrons, they are more or less inert - they don’t react with much at all
Describe the electron structure of metals
They all have one electron in their outer shell which makes them very reactive and gives them similar properties
Describe the ion formation of metals
They can readily lose their single outer electron to form a +1 ion with a stable electronic structure
Describe the reactivity of group 1 elements and why they behave this way
Reactivity is high because there is one electron in their outer shell so they are very reactive. Reactivity increases as you go down the group because the negatively charged outer electron is less strongly attracted to the positively charged nucleus. This is because its further away (more shells) - so its more easily lost, as less energy is needed to remove it
How do you calculate the number of neutrons in an atom?
Atomic mass - atomic number
What is an acid?
An acid is a substance with a pH less than 7
Describe how the pH is related to concentration of ions
The value of the pH is inversely proportional to the concentration of hydrogen ions in a solution. As the concentration of hydrogen ions increases, the pH decreases. This makes sense, because the higher the hydrogen ion concentration, the more acidic something is, so a lower a pH
Describe how to purify crystals with recrystallisation (6)
1) Add a small quantity of appropriate solvent to an impure solid (the crystal)
2) Apply heat to dissolve the solid
3) Pour solution into evaporating disk and gently heat the solution. This is called evaporation. Some of the solvent will evaporate and the solution will get more concentrated.
4) Once some of the solvent has evaporated or when you see crystals start to form (point of crystallisation), you should remove the dish from the heat and leave the solution to cool
5) The salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution
6) Filter crystals out of the solution, and leave them in a warm place to dry. You could also use a drying oven or desiccator (contains chemicals that remove water from the surroundings)
